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Engine Specific Info and Questions => IDI Engine => Topic started by: kuggkrans on February 09, 2006, 06:59:25 am

Title: Tach
Post by: kuggkrans on February 09, 2006, 06:59:25 am
For all of you that dont have a tachometer and dont want to buy a converter for a gasoline tach.


This is done on a volvo 240 VDO tachometer, a vw VDO tach is nearly the same.

First remove the tach from the cluster
http://img156.imageshack.us/img156/5062/tach1by.jpg

Then remove the tach from the holder
http://img301.imageshack.us/img301/4283/tach13wq.jpg

After that remove the circutboard
http://img301.imageshack.us/img301/5595/tach25sh.jpg

Then change the capacitator to 22nF
http://img156.imageshack.us/img156/7720/tach33an.jpg

Then remove the other two capacitators, when you have done that you can put all together and calibrate the tach on the trimmer
http://img156.imageshack.us/img156/8025/tach45xu.jpg

This tach will work on the signal from the W terminal on the alternator
The Bosch alternator that i used gave 6 pulses on the W terminal and the ratio between the cranck and the alternator is 1:2,38.  When you calibrate it do it on the higest RPM possible you get a better reading on lover RPM:s.

If you calibrate it on 5000 RPM the input signal is 1190Hz (5000RPM/60)=83,3r/s

83,3*2,38*6=1190

i think vw have another ratio betveen the cranck and the alternator but that should not be a problem, the range you have on the trimmer is quite large[/img]
Title: Tach
Post by: MattRabbit on February 09, 2006, 02:28:51 pm
If this works, it'd be a really easy thing to try out.  Is anyone brave enough to try it on their VW?
Title: tach
Post by: fatmobile on February 10, 2006, 04:04:24 am
Things looks different in my  '91 Golf gasser tach and my '85 Jetta turbo diesel tach.
 No rectangular caps for one thing.
 The SAK 215 (not visible in the links) pulse shaper chip is in both of them but the other components are different.
 I've been messing with this but it's would be easier to figure out if I had a signal generator/frequncy counter.
Title: Tach
Post by: kuggkrans on February 10, 2006, 04:20:55 am
I have seen other capacitators in older tachs, it can be other shapes than rectangular. i have gotten my hand on a gasoline cluster from a vw -89, dont know witch model. i shall try to modify  that one also.
Title: Tach
Post by: RabbitJockey on February 10, 2006, 07:25:20 am
the one guy has a nice right up on his website about converting a gas tach to work a diesel, but his is done through using a resistor and a variable resistor for fine tuning...

http://www.4crawler.com/Diesel/CheapTricks/Tachometer/index.shtml
Title: Tach
Post by: regcheeseman on February 13, 2006, 06:58:38 am
I was looking to do that to mine, and followed his instructions to the letter - they didn't work. :cry:

I reverse engineered the board and the suggested mods and there was no reason why they would ever work. I emailed the originator of the gasser tacho mod and received no reply.

So  figured - do it myself (I'm an electronics design engineer)

If I recall correctly the w terminal kicks out 25 pulses per rev, the gasser tacho needs 2 pulses per rev.

I used a 4017 divide by ten chip wired in series with the tachos normal input to reduce the W signal down to 2.5 per rev and then used the trimmer in the tacho to get it spot on.

It works perfectly on the bench testing with 'scope and signal generator but unfortunately doesn't like the 'noise' of W terminal when installed in the car. I guess a bit of signal conditioning may sort it out? And if so it has cost me less than 1 to convert my tacho from gas to W terminal  :D
Title: Tach
Post by: fspGTD on February 13, 2006, 11:39:02 am
I came up with this mod a few years ago.  Many have gotten it to work OK on Westmoreland '83-'84 GTI tachometers, but it may not work at all for other kinds of tachometers.

The resistor values will also need some fine-tuning to allow the tachometer to work in the higher RPM area.  It may not be possible to get it to work right at extremely high RPMs.

Relevant threads:
http://www.hostboard.com/cgi-bin/ultimatebb.cgi?ubb=get_topic&f=4037&t=483

http://www.vwdiesel.net/phpBB/viewtopic.php?t=671&start=6
Title: Tach
Post by: regcheeseman on February 14, 2006, 04:54:42 am
Thanks for the link, unfortunately the solution is similar to the previous one suggested.
The various solutions I have found either limit the input signal or vary the resistance of the needle coil or both.

Neither seem to work well with my particular tacho at high revs, the chip becomes unstable just above 1Khz (equivalent to a w signal on a 3000 rpm engine) and shuts down shortly after.
It recovers when the supply is removed.

Hopefully fatmobile's schematics will help me out here.

I phoned the yard that is supplying my engine to get the GTD tacho sent to me as well - "sorry mate, car went in crusher yesterday...."  :x
Title: Tach
Post by: regcheeseman on February 14, 2006, 05:01:25 am
Quote from: "kuggkrans"
This tach will work on the signal from the W terminal on the alternator
The Bosch alternator that i used gave 6 pulses on the W terminal and the ratio between the cranck and the alternator is 1:2,38. When you calibrate it do it on the higest RPM possible you get a better reading on lover RPM:s.

If you calibrate it on 5000 RPM the input signal is 1190Hz (5000RPM/60)=83,3r/s

83,3*2,38*6=1190


I've just re-read though and it may seem that the 25 pulse per engine rev quoted elsewhere may be a little excessive and 14.3 is nearer the mark....
Title: tach
Post by: fatmobile on February 16, 2006, 02:34:19 am
Here's a picture of the '85 Jetta turbo diesel tach:
(http://img51.imageshack.us/img51/7402/dieseltachcircuit2fw.th.jpg) (http://img51.imageshack.us/my.php?image=dieseltachcircuit2fw.jpg)

Here are some hand drawn schematics of the '85 TD tach. The one on the top right is the first draft. The one on the top left is probably the more accurate (notice the 47 uF cap).
 The one on the bottom is of the gasser tach, highlighting the differences between the 2.
(http://img211.imageshack.us/img211/3043/tachschematics9tv.th.jpg) (http://img211.imageshack.us/my.php?image=tachschematics9tv.jpg)
Title: Tach
Post by: regcheeseman on February 16, 2006, 11:13:18 am
Working my way through your schematics...

Where is pin one on the sak215 on your diagram? Is it the same in gasser and diesel?

Any chance of getting a single scan of the gasser sketch, it's difficult to see and doesn't like being enlarged much.

Thanks!

PS - 'ZE' is signal line right?
Title: Tach
Post by: regcheeseman on February 16, 2006, 12:21:46 pm
Does this look right to you? It's the diesel tach.

I was unsure of the cap C4 value - just marked as 3.3 on your sketch.

(http://img501.imageshack.us/img501/2109/dieseltacho5ru.jpg)

No I have it modelled in proteus, I can knock the gas one up pretty quick.

Just need those SAK pin orientation...
Title: tach
Post by: fatmobile on February 17, 2006, 03:46:58 am
Pin 1 ... refresh me on this. That's the pin that if you are looking at the chip from above and the indent is at the top end .. #1 would be top left correct?
 Basically in the schematic, you are looking at the chip from underneath. If you flip it right to left you'll be looking at the chip from the top and #1 would be on your top left. As it sits I do believe #1 is top right. Same on gasser and diesel
 The 3.3 cap (C4) is the small green one at the bottom right of the picture. It only says +3.3 16V on it.
 I'm not sure if ZE is signal line, I'll check. I'm thinking it is because of the AC line under it on the gasser schematic.
 Everything looks right on your diesel schematic.

Quote
modelled in proteus

 Speaking latin at me? ha.
Just took a picture of the gasser tach scheme.
 Trimmed hosted and posted:
(http://img137.imageshack.us/img137/9325/gastachschematic7bn.th.jpg) (http://img137.imageshack.us/my.php?image=gastachschematic7bn.jpg)
 It looks like I went over the gasser tach trying to compare it to the diesel components. Everything in red is diesel.
Title: Tach
Post by: regcheeseman on February 17, 2006, 10:37:06 am
OK, I cleaned up the schematics, first of a re-work of 'fatmobile's' 91 golf gasser tacho schematic...

(http://195.194.142.37/content/m4444424/craigsgasser.jpg)
I'm really unsure about this one, there are a few bits that seem odd, possibly incorrect? It seems too far removed from the 83 version and the TD version to be right?


Now we have the 85 TD Jetta...
(http://195.194.142.37/content/m4444424/craigsdiesel.jpg)
The line from pin 7 coupled to groung via C1 is causing me concern...


My 1983 GTI gasser tacho...- notice the similarities with the 85 TD tacho... :D
(http://195.194.142.37/content/m4444424/mk1gasser.jpg)
I'm 100% sure on this except 1 resistor value (R5) because this has been removed by me during previous modification.

Modified 83 GTI tacho as per instructions from 4crawler link mentioned above
(http://195.194.142.37/content/m4444424/mk1gasser4crawler.jpg)
Notice that it is starting to replicate the TD schematic but  misses crucial capacitor changes.

The load resistor R8 limits the needle swing, I intend to keep full needle swing and modify the tacho face so that 5000 rpm is now where 7000 is - I have some nice template files to create your own custom dials if anyone is interested?

If I make a small change to the TD schematic (added red line it would now match the layout of the gasser schematic, could this line have been missed on your original sketch?
(http://195.194.142.37/content/m4444424/craigsdieselmod.jpg)
Title: red line
Post by: fatmobile on February 18, 2006, 03:43:12 am
Yeah, that red line was drawn in but changed when you flipped the chip.
 The gasser tach is in the car I'm driving so I can't check to see if I got that right. The tach wasn't a seperate circuit on that one it was part of the entire dash circuitry.
 I also noticed there was a diode in series with a resistor between pin 1 and 2 on the gasser tach, that you didn't draw like I did.
On your updated scheme of the '85 TD tach you said:
Quote
The line from pin 7 coupled to groung via C1 is causing me concern...

 That pin  is hooked up to alot of components. the cylindrical golden 47 cap (C1)is one of them. One end connects to pin 7 the other connects to pin 1 (ground).

Nice work. I'm going to have to get them printed out (my printer doesn't work right now). Having the chip flipped is messing with me ... along with scrolling in order to follow the whole thing.
Title: Tach
Post by: regcheeseman on February 20, 2006, 03:33:47 am
Hi,

So leaving the red line was my fault   :oops:

I wasn't too concerned about copying your gasser tach too closely as it seemed to be of a different design.

I have a gas tach open on my bench here and I could see that it bore more than a passing resemblance to the diesel tach circuit you posted. There is no diode on my gasser tacho.

Swapping the gas components to the diesel equivalents should be fairly easy now...doable on the same board.

That chip orientation (component side view) is standard practice over here, is it conventional to view designs solder side where you are from?

That pin 7 is no longer causing me concern, it was the end of the week - my brain had had enough by then!

I have shown electrolytics on my schematic and am guessing that C1 and C3 are electrolytics on the TD schematic.

I'm going to rework the TD diagram to match the gasser one....hold fire on the printing!

Cheers!
Title: tach
Post by: fatmobile on February 21, 2006, 03:24:47 am
Quote
That chip orientation (component side view) is standard practice over here, is it conventional to view designs solder side where you are from

 No I couldn't see the solder traces from the top so I drew it looking at the bottom.

Quote
I have shown electrolytics on my schematic and am guessing that C1 and C3 are electrolytics on the TD schematic.

 Other than that little green 3.3? cap, the rest are cylinder shaped.
 I'm not sure what constitutes electrolytic.
Title: Tach
Post by: regcheeseman on February 21, 2006, 09:59:27 am
Image reworked to match gasser schematic.

Image removed due to error will post the correct one soon...

Quote from: "fatmobile"
Other than that little green 3.3? cap, the rest are cylinder shaped.
I'm not sure what constitutes electrolytic.


Normally cylindrical = eletrolytic but not always.

Electrolytics have polarity and are marked with a black band or similar to denote the negative terminal. Some are also marked with a '+' at the other terminal.
Title: tach
Post by: fatmobile on February 23, 2006, 02:15:46 am
The round caps do have + and - on them.
 I'll get these printed up so I can get a better look at them.
Title: Tach
Post by: regcheeseman on February 23, 2006, 04:14:55 am
Could you double check the values of the caps too? I'm gonna swap my components over soon...
Title: Tach
Post by: RabbitJockey on February 23, 2006, 10:43:37 pm
could someone who does this do a write up on it, i'm considering it, i just need to get a gas tach, hopefully i can find an mk2 gas tach or a cabriolet tach. i hate westmoreland gauge clusters, they're like 20 times harder to read
Title: Tach
Post by: johnny on February 24, 2006, 04:16:28 am
I'm really interested in the tach conversion but I don't know anything about electronics.
The thing I do know is the gastach that's in my car is not a vdo but a motometer, a lot of vw's in europe have a motometer tach build in.

I hope you work it out first with the vdo tach. Is it possible I post a picture of my motometer tach so you can look for the differences.

Johnny
Title: Tach
Post by: MattRabbit on February 27, 2006, 06:12:29 pm
As soon as someone gets one working, post up what needs to be altered on the gas tach to make it work with the W terminal.  I'm not too unfamiliar with a soldering iron to swap some components if need be. ;)

This seems like a very worthwhile project, keep it going!
Title: Tach
Post by: RabbitGTDguy on February 27, 2006, 09:28:23 pm
I'd like to add the early (75-80) MK1 gasser tach to my 79's setup. Its not the westmoreland setup of course... they are the two individual "round" speedo and tach. I'm wondering what the conversion on this will be like...or if it is similar to the gasser tach mods above.

I have Roger Browns optical tach setup in my GTD but would prefer to make a clean stock looking install. Also wish I knew what that damm crank sensor on the TDI read for pulses and whether it is a digital or analog signal. I have the sensor on the motor...will still be there...how could I tell? Anyone know?

Joe
Title: Tach
Post by: regcheeseman on February 28, 2006, 06:07:04 am
Quote
Also wish I knew what that damm crank sensor on the TDI read for pulses and whether it is a digital or analog signal. I have the sensor on the motor...will still be there...how could I tell? Anyone know?


It'll be conditioned as a digital signal and most probably be some for of proxistor (proximity sensor) using either a raised metal blip on the crank or a small hole drilled in the crank. It will measure absence or presence of metal.

The signal will pobably be low level analogue that is fed to an amp, the amp or tacho will then clean the signal up into digital pulses and then count the pulses.

Of course I am completely guessing here...
Title: Tach
Post by: regcheeseman on February 28, 2006, 09:35:52 am
First off, as a reminder, the standard gasser schematic...
images removed by reg.

A simplified diesel tacho schematic
images removed by reg.

Instructions also removed.

The fact that the board has unused spaces probably signifies it's application across a variety of applications

'Fatmobile', any chance you can check those cap values or are you pretty certain?

Just need to do the job and have a vehicle to fit it too...
Title: Tach
Post by: MattRabbit on February 28, 2006, 12:48:28 pm
That's excellent.  As soon as someone tries this with success, I'll do the same.  What would the wattage rating be on the resistors?  1/2 watt?  1 watt?  These should all be parts that we can get at our local RadioShacks, correct?
Title: Tach
Post by: regcheeseman on March 01, 2006, 06:41:04 am
1/4 watt will be fine as there is very little power consumption. VW use 1/2 watts as standard.

Yes the bits should be readily available.

I will do mine today but will have to rig the altenator up to a spare battery and spin it with a drill or something to test it!

I'm still not sure how to calibrate the readout, I can simulate a W signal on the test bench and set it to a known freequency but I have conflicting advice on how many w terminal pulse equal 1 rev  :?  :?  :?
Title: Tach
Post by: Mark(The Miser)UK on March 03, 2006, 05:53:16 am
Quote from: "regcheeseman"

I will do mine today but will have to rig the altenator up to a spare battery and spin it with a drill or something to test it!

I'm still not sure how to calibrate the readout, I can simulate a W signal on the test bench and set it to a known freequency but I have conflicting advice on how many w terminal pulse equal 1 rev  :?  :?  :?


Reg
If you could find an Audi/Golf/Quantum Passat owner near you it would be easy to calibrate it against an existing tach... Now if you lived near Gloucester...
Title: Tach
Post by: regcheeseman on March 03, 2006, 06:25:33 am
Good thinking!

At this rate, I may try to buy a set of GTD clocks, take the schematic from them and use them to re-calibrate my A1 tacho and then sell them on.

Unless someone would like to lend me a set of clocks?  :D
Title: W pulse to rpm ratio
Post by: Mark(The Miser)UK on March 03, 2006, 03:25:45 pm
Subject to the weather and my time and my being able to find my 1950's oscilliscope out in the shed; I'll see if I can note pulse frequency to rpm on  the tach...Edited [over the weekend] :oops:
Title: Tach
Post by: Busdriver on March 03, 2006, 09:06:07 pm
This is slighty off subject, but I found a generic 6000 rpm tach that has 3 terminals on the back, positive, ground, & signal. It also has a four position switch,  4, 6, & 8 cylinder, and the 4th position is marked "12 pole alternator". Will this "12 pole alternator" switch position accept the signal from the "w" wire from the VW alternator?
Title: Tach
Post by: regcheeseman on March 06, 2006, 06:20:19 am
Tried to test the modified circuit board on the weekend,

Rigged up the altenator on the bench but I've had major problems getting my altenator to do anything. }

spent a few hours checking and double checking before stripping the altenator and checking all the internals. I cleaned some contacts and rebuilt it.

Still no joy.

I got my spare petrol alt out and ran that up, it was fine. So I started to swap bits from one alt to the other (needing a working one with a W terminal).

Anyway I went to connect the brokeen alt up and thought 'whoa not that way round and went to swap battery terminals' - it was then I noticed......

For some reson I had been connecting the 'broken' alt up to the battery wrong and when I swapped alt I also swapped terminals.

so I connected it up fine and suddenly my broken altenator is 100%  

Anyway I connected the modded tacho up and span the alt up - the needle moves!!! not much but it moved...maybe up to about 1000rpm? (no face or needle on tacho)

The alt has a ratio of 1:2.4 from the crank and my drill runs 3000 rpm with no load giving an maximum effective crank speed of about 1250rpm.

Facking sweet - looks like its a go!

I have removed some of the previous images as I have made further modifications and will produce the new artwork soon.
Title: Tach
Post by: biobill on March 06, 2006, 09:31:56 pm
I'm just starting into a diesel conversion on a '93 Cabriolet. As the car comes with a tach I found this topic to be very interesting. Turns out, however, that I've got a few different challenges. First, I've got the Motometer gauges (like jonny and other Europeans?). Also, probably because the engine is "run by a computer" in 93, the back of the gauges looks very different (I just ripped the dash apart today and discovered this) something of a ribbon cable covering the entire rear and top of the instrument cluster with a row of resistors on the top.  No 555 chip here. I'm guessing all of the "smarts" are in the computer. Unless someone has some good suggestions (electronics is not my specialty) I'm thinking I've gotta use the older gauge cluster to make anything work (and it has no tach). Hummm... Any ideas?

(http://www.renewableenergyworks.com/transportation/CabbyD/93guagesfront.JPG)
(http://www.renewableenergyworks.com/transportation/CabbyD/93guagesrear.JPG)

PS If those pictures don't show up (I'm new at this) you can go directly to
http://www.renewableenergyworks.com/transportation/dieselcabby.html
to see the gauge pictures and more.
Title: Tach
Post by: regcheeseman on March 08, 2006, 04:54:27 am
Biobill,

Depends entirely on what diesl you are using.

But your guages sound perfectly normal - the ribbon on the back (membrane) is common to all clock assemblies.

You need to take the clocks apart to get to the guts of the tacho - which is where you should find the board with the chip (SAK215) is....... maybe. :?
Title: Tach
Post by: biobill on March 08, 2006, 10:15:45 am
Thanks! I guess I was expecting to see something different. I'll keep digging and let everyone know what I find!

I've got a 1.6 NA diesel from a 1981 Rabbit to put in. The fun has just begun!
Title: Tach
Post by: regcheeseman on March 08, 2006, 11:03:14 am
Ok, here we go...

The original gasser schematic
(http://195.194.142.37/content/m4444424/final_gasser.jpg)

Re-worked into diesel w terminal version
(http://195.194.142.37/content/m4444424/final_diesel.jpg)

The gasser board before (click to enlarge)
(http://195.194.142.37/content/m4444424/GasserPCBsml.jpg) (http://195.194.142.37/content/m4444424/GasserPCB.jpg)
replace R1 with 100 ohm
leave R2  
replace R3 with wire link
replace R4 with 191 ohm
replace R5 with wire link
replace R6 with 10K
replace R7 with 15K

 
replace C1 with 10nF
remove C2
leave C3
remove C4
replace C5 with 47nF
fit C6 3.3uF in vacant spaces next to tacho motor (red and blue) wires or desolder wires from board, fit cap and then solder wires to cap wires/board.

adjust RV1 to mid range

The final working board.
(http://195.194.142.37/content/m4444424/final_board.jpg)

Note the two resistors joined together are because I could not find a 191 ohm resistor so joined a 180 and a 10.

C6's value is not critical, I used a 2.7 instead of a 3.3, it works fine without this cap altogether and I believe is only there to stop needle flutter (I didn't have a problem with or without this fitted)

Job done!
Title: tach
Post by: fatmobile on March 09, 2006, 01:40:28 am
Next we do it to a Rabbit Gti instrument cluster.
Title: Tach
Post by: johnny on March 09, 2006, 04:00:38 am
In the last week I discovered VW jused a lot of different setups on the tachs. Even the same brands can be found with different setups. Last week I bought a original '90 GTD cluster to replace the tach into my gas-cluster but found out this was not possible because here they used the main printcircuit for the tach and not a stand alone on the tach.

I'm now trying to compare my '86 gastach from motometer with the vdo of regcheeseman. I don't know much about electronics but I can see different resistors, capacitors and a different IC on the printcircuit.
I will post a pic of my motometer and hope someone can help me out.
Title: Tach
Post by: regcheeseman on March 09, 2006, 04:33:32 am
Quote
Next we do it to a Rabbit Gti instrument cluster.


Mine started out as a Golf GTI cluster..... is it not the same?
Title: Tach
Post by: vwmike on March 09, 2006, 04:46:59 am
Quote from: "regcheeseman"
Quote
Next we do it to a Rabbit Gti instrument cluster.


Mine started out as a Golf GTI cluster..... is it not the same?


In the US we got US made Rabbit GTI's. They are very different. Here is mine:

(http://www.tdtuning.com/pictures/rabbit1.jpg)

And here is the instrument cluster:

(http://www.tdtuning.com/pictures/cluster.jpg)
Title: Tach
Post by: mortskeg on March 09, 2006, 04:55:59 am
Hey guys,
Well the westmoreland style tach like in the 83-84 gti's is a bit different.  We've got a big pink box looking thing and some other chicklet gum looking things... haha.  You've inspired me though, cheeseman.

Here's my feeble attempt at doing the above with the westmoreland gas tach circutry.  Unfortunately the flipside of the board is white, so the yellow lines were hard to see, so I made them blue.  I couldn't tell with the solder if some of the areas near the trim pot were maybe connected?  They kinda looked like it but it doesn't really make sense to me.  Anyhow, everybody feel free to correct what is wrong, or use this image how you wish.  Keep up the good work and let me know if there is any info you need regarding the US tach. Cheers!

(http://img.photobucket.com/albums/v400/glen_ekstrom/gastachboard2.jpg)
Title: Tach
Post by: regcheeseman on March 09, 2006, 07:00:49 am
I'm on it Morts!

The big pink thing, has it got an adjustment screw?

I'll need numbers, colours, values whatever I can't make out on your images....

Let me just annotate the image and knock up a schematic first....
Title: Tach
Post by: regcheeseman on March 09, 2006, 08:15:53 am
Mods for westmoreland clocks...

First the schematic as is..
(http://195.194.142.37/content/m4444424/morts_gasser.jpg)

The annotated board..
(http://195.194.142.37/content/m4444424/gastachboard2ann.jpg)

A lot of similarities with the original VDO circuit, I'll wager the SAK chip is the same and converting to the diesel tacho circuit should work..

Make R1 = 100ohm
replace R2 with 72ohm
replace R3 with wire link
replace R4 with 191ohm
replace R5 with wire link
replace R6 with 10K
replace R7 with 15K

replace C1 with 10nF
leave C3
remove C4
remove C?


make RV1 = 22K
remove RV2 and replace with 47nF cap

If you can get a 3.3uF across the needle output wires then do so....I've no idea why, guess the blokes at VDO just liked drawing capacitors!


God am I bored at work today!
Title: Tach
Post by: RabbitGTDguy on March 09, 2006, 10:20:37 am
I've got a fun one for you then...

I was using the optical setup that roger brown advertising in conjunction with the Westmoreland style GTI cluster, works well...but isn't as "clean" as I'd like the setup to look this time around.

I'm also having to change directions a little bit with my mTDI project and without getting into details I'm going to use an early cluster. I was able to get the early tach with it as well and I pulled the board today to see how it compared to the boards already up here and it looks different...so, yet another variation... think we could make it work off the W terminal? My setup will be using the serpentine belt MK3 style, non a/c etc.... the alternator on the MK3 also has the W provision there as well. Should be accurate with serp too because of the fact that they are harder to slip...

So, now I want to post a pic of the board for all to see but it seems that the fiancee must have take my digi camera to school for some pics today! Will post pics later then i guess.

Its a motometer tach  from '78 MK1 or so...

Joe
Title: Tach
Post by: regcheeseman on March 09, 2006, 10:31:49 am
I know sod all about TDI's but i'd guess that there would be a better signal available than the one from the W term to drive a tacho. Bit of a pointless exercise converting to W term operation.
If you can find the tacho drive signal, I can help you make it work with the old dash.
Title: Tach
Post by: RabbitGTDguy on March 09, 2006, 11:03:01 am
i'm not using any of the TDI electronics, I'm using a mechanical pump, etc. so there is not ECU, etc.
I had played with the idea of using the crankshaft sensor that comes on the TDI...but from what I've read its a digital signal more than likely and I'd have to convert from digital to analog.

The other option is just to run the optical setup I have...
 
I'd like to make this early tach work either way though... either off the W, optically or even with the TDI's crank sensor (which I still have :) ) if it was at all possible...

Joe
Title: Tach
Post by: regcheeseman on March 09, 2006, 11:38:47 am
Run with the crank sensor, you need a digital signal - not an analogue one.

Go with the 4crawler optical circuit, it should be the same, except you have a factory sensor  :)
Title: Tach
Post by: RabbitGTDguy on March 09, 2006, 12:34:08 pm
very cool...i'll have to see if it would work. I thought I'd have to have some sort of convertor to make it work...but it is possible that the TDI unit could work...and it'd be a "clean" install def. If it uses the same number of pickups... Rogers optical setup uses 4 pickups i believe...i'll have to count the cutouts on the VW sensor plate (on crank) to see how many it has. Would be cool if i could use it that way!

Joe
Title: Tach
Post by: mortskeg on March 09, 2006, 03:45:50 pm
You're the man, regcheeseman!
Not that it must matter if it would get removed, but it looks like the C? has a 10.3 or a 103 printed on it, it is pretty faded.  The majic pink box is sans adjustment screw, unless it's on the bottom :P   It just has 2 terminals that go through the board.  The top is placarded 0,22K250-R1/  Thanks again for doing the interpretation/conversion post; hopefully it will be of some help to the US guys.   :D
Title: Tach
Post by: regcheeseman on March 10, 2006, 04:18:04 am
Quote
Rogers optical setup uses 4 pickups i believe...i'll have to count the cutouts on the VW sensor plate (on crank) to see how many it has. Would be cool if i could use it that way!


Four? Seem a bit odd.

I could imagine it having four zones on the detector plate to give 2 pulses per rev and thus match the normal input from the gasser's coil.

Can you link me to any information?

Chances are your engine will have a single pulse or possibly two or more or varying duration.
Title: Tach
Post by: mortskeg on March 10, 2006, 03:20:41 pm
Not to step on GTDguy's toes- but maybe this is the link you wanted?
http://www.4crawler.com/Diesel/CheapTricks/Tachometer/index.shtml
Hope this helps. :)
Title: Tach
Post by: RabbitGTDguy on March 10, 2006, 06:21:12 pm
i should have clarified i guess.... 4 on, 4 off. but thanks for posting the link, was about to do that here.

I'm just wondering if it could work on the TDI's sensor base, I'll take pics of it and it's pickup wheel here tonight...

Joe
Title: Tach
Post by: johnny on March 11, 2006, 10:37:18 am
This is the pic of a motometer gastach from a '86 mk2. I hope there is some similarity with the US-tachs so this can also be converted to work on a diesel.

(http://gallery.vwcaddyforum.nl/albums/userpics/10067/normal_gastach.JPG)

Here is the big pic: http://gallery.vwcaddyforum.nl/albums/userpics/10067/gastach.JPG
Title: tach
Post by: fatmobile on March 13, 2006, 03:38:11 am
That's the first one I've seen that doesn't used the SAK 215 chip.
 That looks like a texas instruments chip but I can't see the part numbers ....or get the big picture to fully load (bad dialup connection I think).
Title: Tach
Post by: regcheeseman on March 13, 2006, 05:02:49 am
Read the 4 crawler link and a lot of it seems hypothetical. Maybe his 4 pulse application worked but every 4 cylinder single coil motor I've ever worked on had 2 pulses per rev...

Oh no. I've just sussed it... probably should have read the text it may have been explained.

He was taking a signal from the injection pump and the injection pump runs at half engine speed hence doubling the pulses!

Let me know the TDI setup.

Johnny,

If you can photograph the other side of the board I may be able to help but I doubt it very much - it has the wrong chip.  :(
Title: Tach
Post by: RabbitJockey on March 13, 2006, 04:32:29 pm
good info, would the golf gti tach that regcheeseman be the same as a cabriolet tach?  cause i could get a cabriolet tach pretty easily, and it slip right into my car since jettas and cabbys had the same dash.
Title: Tach
Post by: RabbitGTDguy on March 13, 2006, 09:46:58 pm
Quote from: "regcheeseman"
Read the 4 crawler link and a lot of it seems hypothetical. Maybe his 4 pulse application worked but every 4 cylinder single coil motor I've ever worked on had 2 pulses per rev...

Oh no. I've just sussed it... probably should have read the text it may have been explained.

He was taking a signal from the injection pump and the injection pump runs at half engine speed hence doubling the pulses!

Let me know the TDI setup.

Johnny,

If you can photograph the other side of the board I may be able to help but I doubt it very much - it has the wrong chip.  :(


As and you shall receive. I have not had alot of luck with finding info on the sensor specifically...however, I do have pics.

1z TDI crank sensor
(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2217.jpg)
(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2218.jpg)

crank "pickup" wheel  You can see the pickup wheel on the left side of the crank against the rear seal housing as well as the "cut" in it. There are 4 of these...
(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2107.jpg)

I know its not much info... but I'm working on getting more :)

Joe
Title: Tach
Post by: johnny on March 14, 2006, 07:01:58 am
I will try to disassemble it further so you can see the other side of the printing circuit and take some pics.
What you see on the pic is the whole tach assembly, you can click it right in your cluster. On the tach you have four pins (+,-,ZA and ZE), I don't know where ZA and ZE stand for. Maybe someone can help me out ?

@ fastmobile
Is this maybe the first european tach you see ?
Title: PCB from 93 Cabriolet with MotoMeter tach
Post by: biobill on March 14, 2006, 09:22:22 pm
OK, I've dug in and found the board for my tach!
Hopefully not too different, despite the unique chip - TI 9236XRX and the little thing below R3 & R2 - I believe the board says ZD1 (obscured) and BZX (very small) is written on the component. Here are the pictures:
(http://www.renewableenergyworks.com/transportation/CabbyD/93tachPCB.JPG)

from my poor decoding skills, I'm guessing
R1 = 23k
R2 = 220
R3 = 2.2k
R4 ? 210? help!
R5 = 82
R6 + 100
R7 = 25k
R8 = 22k variable

C1 = 2200
C2 = 0.22 uF
C3 = 22M
C4 ? 220T

I've tried to sketch out the schematic and it seems to share many characteristics of schematics already presented by regcheeseman. Pardon the low tech sketch.
(http://www.renewableenergyworks.com/transportation/CabbyD/93cabbyschematic.jpg)

Have I got a chance??  Thanks in advance for any/all help, and let me know if you need more info to decipher!
Title: Tach
Post by: fspGTD on March 14, 2006, 10:31:54 pm
Biobill: The component below R2 and R3 looks like a diode to me.  I'd guess it's a zener diode type, because of it's label ("ZD1").

All: keep up the great work going on in this thread! :)
Title: Tach
Post by: regcheeseman on March 15, 2006, 07:29:06 am
That TI circuit is exactly the same! (Johnny you may have a chance if you get me images of both side of board)

But for BIOBILL I'm reckoning; using the designations on your board...

Swap R1 for 15K
Remove R2
Remove R3
Swap R4 for 191 ohm
Swap R5 for 72 ohm
Swap R6 for 100 ohm
Swap R7 for 10K

Replace zener with wire link

Swap C1 for 10nF
Swap C2 for 47nF (nanofarad)
Swap C3 for 47uF (microfarad)
Swap C4 for 3.3uF

If replacing C3 or C4 with electrolytics then observe polarity as marked on board.
Title: Tach
Post by: biobill on March 15, 2006, 11:40:20 am
Thanks guys for the thread and the specific help. I've added my sketch of the schematic in my post above in hopes that it will help others (hopefully I got it right). I'll make the changes to the board, get the gauges back in the car and let everybody know how it works. Any guess on how much "calibration" will be involved? I'm guessing that's what the variable resistor is for.

I'm wondering if it's worth it to get a gauge overlay to expand the scale. I'm thinking for now I should just see if I can get it to work, and  :o oh yah  :o get the diesel swapped into the Cabriolet before summer gets here!
Title: Tach
Post by: regcheeseman on March 15, 2006, 12:23:08 pm
Quote
I'm wondering if it's worth it to get a gauge overlay to expand the scale. I'm thinking for now I should just see if I can get it to work

You can use the variable to calibrate it to work with either the gasser or diesel scale.

Here's your PCB image reworked..
(http://img109.imageshack.us/img109/8176/biobillpcb7yn.th.jpg) (http://img109.imageshack.us/my.php?image=biobillpcb7yn.jpg)

And a 5 minute lash up of your schematic - some differences to your version.
(http://img80.imageshack.us/img80/2126/billsgasser0mu.th.jpg) (http://img80.imageshack.us/my.php?image=billsgasser0mu.jpg)


16 mar - schematic edited for additional line between pin 1 and GND - sorry!
Title: Tach
Post by: YoSono on March 15, 2006, 05:09:00 pm
In response to all the great work that Reg & Fatmobile are doing, i decided to redraw some stock looking Tacho faces that are in relation to the diesel rev range - inspired by the mk2 GTD tacho clocks. The NA spec one was more tricky to do than the euro one, but if your a sucker for factory fresh looking details, then hopefully you'll enjoy these as much as me.

If anyone wants a high-res printable version (they are all to scale, and the correct size, all you need to do i press print! or get someone to print em for ya) then drop me a PM, and i'll get back to you :)

cheers y'all

lee.

(http://www.wearecentralpark.com/misc/diesel_tacho_faces.gif)
Title: Tach
Post by: RabbitGTDguy on March 15, 2006, 06:51:05 pm
man...those look great!

I would like to rework a set of the early clocks for MK1 with the gasser tacho... they are roundies...but would be cool with the correct tach readout. :) Anyone good with that kind of magic?

I have similar NA versions in "white faced" units with corrected rpm range for a diesel on the westy style clusters. Also has a Rabbit symbol and "GTD" on them as well. Tim Cooper made them a while back...

Joe
Title: Tach
Post by: mortskeg on March 15, 2006, 11:22:31 pm
Ah Central Lee!
Now I know that YoSono=Lee.  Very nice.  You are the man; keep up the good work. :)
Title: Tach
Post by: fatmobile on March 16, 2006, 02:52:55 am
regcheeseman,
 Great work. It looks like you have this circuit figured out. Doesn't seem like it takes you much time after looking at the circuit to have it drawn up and posted. Glad you came along or for me it would still be scribblings on paper.
 I got the instrument cluster out of my '83 Gti and it looks just like mortskeg's.
 I'd like to run my engine up a little higher than stock RPMs. Is there a way to get it to register 6000 RPM or to match the scale of the stock gasser tach?

 
Quote
@ fastmobile Is this maybe the first european tach you see ?

 You talking to me? fastmobile ha. I like it ... might have to change my name. :lol:
 That is the first euro tach I've seen.
Title: Tach
Post by: regcheeseman on March 16, 2006, 04:41:20 am
fatmobile,

Will run to 6K no problem - as long as your engine can!
Title: Tach
Post by: johnny on March 16, 2006, 06:42:06 am
Here is the schematic of my gastach, I hope it is usefull.
(http://gallery.vwcaddyforum.nl/albums/userpics/10067/normal_gt-front.jpg)
(http://gallery.vwcaddyforum.nl/albums/userpics/10067/normal_gt-schematics.jpg)

For bigger pictures you can click the following link:
http://gallery.vwcaddyforum.nl/displayimage.php?album=214&pos=47

I've seen a lot of similarity with the tach of Biobill, I think I'm getting the hang of it  :lol:

Some numbers:
tachnumber: MOTOMETER 54401 201 00
chip: sn29736p 627x
c1: U7 10%
c2: U9 100V MKT1813
c3 and c4:U9 10V 22
v1: ZPD 68
variable: 22K

r1 - r7: I really don't have a clue

Let me know if you need more info, I really appriciate all the help

@fatmobile: sorry, but fastmobile also sounds great  :oops:
Title: Tach
Post by: regcheeseman on March 16, 2006, 08:44:07 am
Johnny,

Could you just turn the board over and take a photo at the same scale?

It makes my job MUCH easier!

Also, the numbers you have written on the components, are they the ones actually printed on the board?
Title: Tach
Post by: RabbitGTDguy on March 16, 2006, 10:56:03 am
I'll have to get cleaner pics later... but here is the board of an early German motometer tacho... 77-80 style... gas

(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2260.jpg)
(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2262.jpg)
(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2259.jpg)

For those that might like to add the tacho to their setup. This is the one I'd like to use... :)

My camera batteries just died...so i'll have to update pics later...

What did you think of that TDI crank sensor shot I posted?

Joe
Title: Tach
Post by: regcheeseman on March 16, 2006, 11:17:20 am
do you have a flash on that camera?

And could you put it into macro mode (little flower button) and get a bit closer?

As for the TDI crank sensor, I reckon the standard gasser tacho may cope with that setup with some small screwdriver tweaks. You will have to use an amplifier circuit (4crawler link) to fit between sensor and tacho though.
Title: Tach
Post by: RabbitGTDguy on March 16, 2006, 11:32:10 am
There...updated, just replaced the previous ones I had taken above... I can try again later if those don't work...

As for the amplifier and using the regular tach... that'd be interesting.. Is that the one you get from Dakota Digital? I know they have a "W" interface, but I'll have to read through and see if they also are the ones that carrier the amplifier that you are speaking of. Would be nice to use the stock sensor...if not though, i may modify this tach i have pictured to work on the W terminal...

Joe
Title: Tach
Post by: johnny on March 16, 2006, 01:36:48 pm
Quote from: "regcheeseman"
Johnny,

Could you just turn the board over and take a photo at the same scale?

It makes my job MUCH easier!

Also, the numbers you have written on the components, are they the ones actually printed on the board?


Here's a picture of the back of the board.
(http://gallery.vwcaddyforum.nl/albums/userpics/10067/normal_gt-back.jpg)

And I made a layover of the back on the front of the board (Hoping to take some work out of your hands.
(http://gallery.vwcaddyforum.nl/albums/userpics/10067/normal_layover.jpg)

The numbers on the components are exactly the same numbers as on the board.

(Is there also a regcheeseman fanclub, I would like to be part of it  :lol: )
Title: Tach
Post by: RabbitJockey on March 16, 2006, 02:05:22 pm
this is awesome, once this is all figured to a 100%  a faq post must be made.
Title: tach
Post by: fatmobile on March 16, 2006, 11:55:25 pm
I suppose after we get one built we need to calibrate it.
 I was looking for frequncy counters on ebay and saw a gadget that had a wire wound up in it.
 The plan was to set it on the engine (might have had a magnetic base) The wire would pull out like a tape and as it was pulled out it would vibrate from side to side. Pull it out a little more and the swing of the wire's vibrations would be reduced.
 Find at what length it moved the most and the device had a pointer that would indicate the frequncy.
  Each frequncy would be represented by a different length of wire. I don't know how accurate it would be. Maybe a very little difference in length would represent a large change in RPMs.
 Either way we are going to have to figure out an easy way to calibrate our tach conversions.
Title: Tach
Post by: mortskeg on March 17, 2006, 02:02:02 am
When I installed my gas tach and signal converter, I simply figured out what rpm I should see at a given speed (60mph) in 5th gear.  I figured this out based on my tire size, gear ratio, and final drive.  If you'd like I can dig up these equations.  Of course I used a handheld gps to accuratly maintain the 60mph since the vw speedo is, well, a vw speedo. :)

It also helped that calibration was easy to do since I just had to bump the tach needle up/down by pressing the calibration buttons on the signal converter mounted on the kneebar which was then covered by the kick panel thing.

Hope this helps.

(http://img.photobucket.com/albums/v400/glen_ekstrom/dieseltach.jpg)
Title: Tach
Post by: RabbitGTDguy on March 17, 2006, 06:01:25 am
As requested (but replaced the pics on page 5 as well...) the 77-80 MotorMeter gasser tach for any of those of us having early MK1's using diesels with W's that might want to use this gauge.  

(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2260.jpg)

(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2262.jpg)

(http://i18.photobucket.com/albums/b109/joeallison_99/TDI%20ENGINE/100_2259.jpg)

Joe
Title: Tach
Post by: regcheeseman on March 17, 2006, 06:05:15 am
Quote from: "trev0rbr"
this is awesome,


The only thing awesome about it is the number of different PCB configurations that are coming out of the woodwork - I wish I'd kept quiet about it now.

 :wink:  :D

I've calibrated mine on the bench with a frequency generator with inbuilt counter. when I did this my variable resistor network measured 23.4K - so taking the fixed resistor of 10K out means the variable was set to 13.4K. Which is why I suggest midrange as a base setting.

I guess you could use a strobe on the top pulley

I was thinking either fit a w term alt onto a gasser VW and compare the diesel tach against the gassers one.

Or plug the tacho into another VW diesel that has a tach and a W terminal
Title: Tach
Post by: regcheeseman on March 17, 2006, 07:19:54 am
Rabbit GTD guy,

still had problems with your photos because they were at different angles but I gleamed enough to note it was exactly the same as BioBill's unit including the component designations so your instructions are exactly the same!
Title: Tach
Post by: regcheeseman on March 17, 2006, 08:09:20 am
Johnny,

Use the component designations as per below and you have exactly the same circuit as Biobill and RabbitGTD - so again follow the instructions I gave BioBill.

Leave the terminal marked ZA disconnected

(http://img48.imageshack.us/img48/9584/johnnypcb9yw.jpg)

Cheers!
Title: Tach
Post by: johnny on March 19, 2006, 10:52:45 am
Next weekend we will rebuilt the tach and install it, I think I'm going to use a strobe or make the variable outside of the tachunit so I can calibrate it more easily after the tach is installed in the dash.
I will let you know next week how it went.

Thanks again cheeseman  :wink:
Title: Tach
Post by: RabbitJockey on March 19, 2006, 06:23:19 pm
we have these neato strobe lights at school that we used to see the rpms of little electric motors.  it had a read out of the rpm on the back and then you adjusted knobs until the mark on the wheel on the drive shaft of the little electric motor would "stay in place"  and of course, assuming the motor wasn't at double that speed, you found the correct rpm.
Title: Tach
Post by: Kudagra on March 19, 2006, 08:29:03 pm
Newer Bobcat loaders use a magnetic pick-up. Basically just a digital on/off switch. Think that would help anyone. I can probably get a few.
Title: Tach
Post by: regcheeseman on March 20, 2006, 06:27:38 am
I took delivery of a set of A2 GTD clocks this weekend, I have just gone over the schematic (pretty tricky as board contains MFA stuff as well as tacho circuit)
But it is pretty much the same as the conversion board except for non important component value changes.

Anybody want a set of GTD clocks? Will fit A1 or A2 - some small loom mod required for A1 install.

Oh and all you motometer owners.... I not 100% sure on the original component values versus the VDO unit that I have succesfully swapped. It SHOULD be the same but I don't think it was every really answered.

Someone do a motometer.... if one type workswhen modified, they all should :D
Title: Tach
Post by: johnny on March 21, 2006, 04:50:04 am
Another little question:

does the voltage of capacitors matters or doesn't this have any influence on the tach. (I noticed I have one 100V capacitor and a couple of 10V)
Title: Tach
Post by: regcheeseman on March 21, 2006, 05:38:43 am
You should use caps greater than or near to the expected circuit value (12V ish in this case).

However my factory unit uses 10V caps - so you should be fine.

The 100v will be ok as well to use - aside from being slightly physically larger than the equivalent lower voltage version.
Title: has this been beta (road) tested?
Post by: alphawerks on March 23, 2006, 02:59:32 pm
Has anyone had success with this in their car? Seems to be proving problematic at the moment. Just curious if it's me or the hardware.
(90 td, 83 gas tacho) Goes to 4k on power-up, then 5k running, with no change due to RPM. Checked the shematic several times, tried the 'conversion' instructions, and the 'original' td schematic setup. Any ideas?

Ryan
Title: Tach
Post by: regcheeseman on March 24, 2006, 04:45:06 am
I've got no car to try it with at the moment....

(http://img164.imageshack.us/img164/1175/underseal8kj.th.jpg) (http://img164.imageshack.us/my.php?image=underseal8kj.jpg)

But I've ran it up to around 1000rpm with the altenator in a vice being turned by a drill.
And I've also simulated the W signal up to 7000rpm in the lab with no problems.

What tacho did you start with? Your problems are not something I have experienced during any of the development work except when I left a resistor in by mistake early on - it would whizz round to full revs showing without any w terminal signal applied.

I've built another conversion for a similarly afflicted caddy nut, but he has no way of testing it either....
Title: westmoreland tach
Post by: fatmobile on March 24, 2006, 04:43:31 pm
That is a very nice tiltisorie ... bad spelling I'm sure but it tilts the car up on it's side nicely. I've been eyeing a few on the vortex and this one looks great compared to some of them.
 I was messing with the '83 westmoreland tach, figuring what parts I need to source.
 It looks like there are a few resistors that can be moved from one spot to another.
 R6 is a 15K resistor and can be moved down to where R7 is. Then a 10K is used in the R6 spot.
 R3 needs to be a wire link and is a 100 ohm now. On the diesel tach, R1 needs a 100 ohm resistor so that can be used there.
  Actually I'm thinking the R1 resistor determines how far the needle swings so I might put a variable resistor in there and see if I can get it to work with the stock gas tach face and go to 7000RPM.
 The stock R1 resistor in the gasser tach is about 10ohm (it was 15ohm in my '91 Golf gasser tach) so I might even keep that one in there.
(http://img218.imageshack.us/img218/5563/gastachboard2ann7hh.th.jpg) (http://img218.imageshack.us/my.php?image=gastachboard2ann7hh.jpg)
 ...so the parts list looks like:
10K resistor
 72ohm resistor
191ohm resistor
 and a 10nf cap (the '91 Golf already has a 10nf cap that is getting removed)
 4 little pieces
Title: Tach
Post by: regcheeseman on March 27, 2006, 04:50:18 am
Quote
That is a very nice tiltisorie ... bad spelling I'm sure but it tilts the car up on it's side nicely. I've been eyeing a few on the vortex and this one looks great compared to some of them.


re-posted from - http://vwcaddyforum.com - I never knew what to call my roll-over frames - but I like TILTISORIE  :D

Quote
I made these from 50 mm box steel and cost about 70 in materials alone.
(http://img156.imageshack.us/img156/214/stands22wk.th.jpg) (http://img156.imageshack.us/my.php?image=stands22wk.jpg)

They are welded up so the caddy is held slightly over centre - please note I facked up the angle cuts on the bottom of the stand, and the brace is in a different place to drawings - please follow the drawings (I didn't!)

(http://img103.imageshack.us/img103/7299/pict39941kq.th.jpg) (http://img103.imageshack.us/my.php?image=pict39941kq.jpg)

Cut the box up as follows..and weld together
(http://img103.imageshack.us/img103/29/cutting2ko.th.jpg) (http://img103.imageshack.us/my.php?image=cutting2ko.jpg)

And make the mounts as shown..
(http://img103.imageshack.us/img103/8486/mounts9hk.th.jpg) (http://img103.imageshack.us/my.php?image=mounts9hk.jpg)

I bolted the mounts up to the car, then offered the front frame up so there would be just enough gap between bottom of stand and wing (about 1" with a mate stood holding a 1" plank against the car.) I then tacked it in place and then did the same to the back frame.

I unbolted the lot and welded it all up at work good and solid.

To lift the car I just slide a bar in one of the frames to make a lever and lift - I can do it on my own no probs.
To drop it down again, you need two as its impossible to push the car from one side and hold it on the ther side on your own.

It is dead easy with two though.

Quote
Actually I'm thinking the R1 resistor determines how far the needle swings so I might put a variable resistor in there and see if I can get it to work with the stock gas tach face and go to 7000RPM.

No, you could cause the tacho chip to overload and shutdown - the RV1 R7 network control all the timing with C2.
It will go to 7K no problem. The 10 ohm will be fine instead of the 15
Title: Tach
Post by: johnny on March 27, 2006, 11:22:57 am
My tach just gave the first sines of live, tonight I'm going to try calibrating it. At idle it runs at 1200 rpm an with a little gas it goes straight to 7000 rpm.
Title: Tach
Post by: johnny on March 27, 2006, 02:58:33 pm
Tonight I calibrated my tach an it works just fine.

Thanks regcheeseman, if I can do anything for you just let me know.
Title: Tach
Post by: regcheeseman on March 28, 2006, 06:20:29 am
Quote
Tonight I calibrated my tach an it works just fine.

RESULT!

Quote
Thanks regcheeseman, if I can do anything for you just let me know.


There's a few things you could post me over  :wink:

drugs, porn, ladies????   - Nah Salt Liquorice or Bosch Bolle  <sp?> :lol:

Not really buddy, just knowing that it worked is good enough!

Cheers!
Title: Tach
Post by: biobill on March 29, 2006, 11:36:44 am
OK! Thanks to all the help here, I got the circuit board rebuilt
(http://www.renewableenergyworks.com/transportation/CabbyD/rebuiltPCB.JPG)
(note the fancy resistor work to get the right value) and the whole dash is back in the car!
(http://www.renewableenergyworks.com/transportation/CabbyD/newtachindash.JPG)
Now I've gotta get the new engine in so I can check if it works and to do any calibration.

A couple questions:
1) Now that I've rebuilt the tach, do I dare start the gas engine (to move it onto the tow dolly to get it to the garage) or will that "blow up" the tach??

2) Calibrating might be a pain, I'm thinking one solution might will be to cut a small hole in the side/back of the tach housing through which I can stick a small screw driver to turn the variable resistor. Any other ideas? and does increasing resistance increase or decrease needle swing?

3) And related to the whole dash rework theme, has anybody added a glow plug light to a gas dash? I've searched a bit and not found anything.

Thanks again for all the help!
Title: Tach
Post by: johnny on March 29, 2006, 12:57:36 pm
For calibrating I drilled a little 6 mm hole in the back of the tachhousing.
Turning the variable to the right gives more needle swing.

To add a glow plug light you can look at www.t3-info.de , as they discribe it it must be really simple.
Title: Tach
Post by: biobill on March 29, 2006, 08:43:26 pm
I'll drill the hole!

As for the link for the glow-plug lights, I searched around the site a bit and found something similar under "Kontroll-Leuchten", but these seem to be back-lit whereas our lights have the symbols above or below an actual light.
(http://www.t3-infos.de/images/Kontrolleuchten_Harald.jpg) versus  (http://www.renewableenergyworks.com/transportation/CabbyD/warninglights.JPG)

My German isn't as good as I'd like - did I miss something??
Title: Tach
Post by: RabbitJockey on March 29, 2006, 09:49:53 pm
i thought you could switch the center section over from your old instrument cluster, just like mr caddy on his website.  or is that only on cluster that are the same design as the diesel one you started with?  i plan on using a cabriolet tach and cluster, it will give me a 100 or 120mph speedo and a tach, plus all the plugs are the same, and it will sit right in perfectly fitting into my jetta.
Title: Tach
Post by: regcheeseman on March 30, 2006, 04:00:36 am
Biobill,

Guess what, I've done the glow light install!  In fact I swapped all the lamps/LEDs for crystal clear LEDS including the one in the temperature gauge.

Even built a LED green backlight for the digital clock - credit to Yo Sonno (sp?) for that idea though - he has gone one better and reversed the polarity screen on his clock to get white digits on a dark background and then backlit it with Blue LEDs!

(http://img78.imageshack.us/img78/7752/blue7yw.jpg) (http://imageshack.us)
(http://img78.imageshack.us/img78/2199/blue25yi.th.jpg) (http://img78.imageshack.us/my.php?image=blue25yi.jpg)

These are his pictures - hope he doesn't mind!

Anyway back to the glowlight, fit an LED, poke it through the membrane and solder it carefully to the membrane (get it the right way round!)
I think an additional resistor needs to be added in one of the vacant spaces too - i'll go check what and where...
Title: Tach
Post by: YoSono on March 30, 2006, 04:34:40 pm
ahhh cheers for the mention regcheeseman... and it's "YoSono" aka "Central Lee" on the caddyforum.

Yeah, once i get the led's just how i want em, it really does make the lighting much better than stock... pfftt, which is like having some kinda half arsed glow worm illuminating the clock at night.

hehe :)

lee.
Title: caps
Post by: fatmobile on April 03, 2006, 06:07:36 am
regcheeseman,
 What kind of caps did you use?
 The ones in there were cylindrical but the ones you used aren't.
 Are they ceramic? Mylar?
Which of these if any would work best?
Mylar:
http://cgi.ebay.com/Radial-Mylar-Capacitors-01uF-50V-5-Panasonic-50_W0QQitemZ7603094436QQcategoryZ40113QQrdZ1QQcmdZViewItem
 mono ceramic:
http://cgi.ebay.com/01uF-20-50-Volt-Mono-Ceramic-Capacitors-30pcs_W0QQitemZ7600064713QQcategoryZ36335QQrdZ1QQcmdZViewItem
disc?:
http://cgi.ebay.com/25pk-01uf-50V-Disc-Capacitors_W0QQitemZ7596820559QQcategoryZ36335QQrdZ1QQcmdZViewItem
 I saw the black line on yours that indicates the negative post ... but I didn't see polarity on any of these ebay caps.
Title: Tach
Post by: regcheeseman on April 03, 2006, 07:25:05 am
It doesn't matter if they are electrolytic or non-electrolytic

It doesn't matter what they are made of as long as they can cope with at least 12V and are the correct capacitance.

Ebay is a VERY expensive way to buy them - don't you have Radio Shack or similar electronics hobbyist type shops or catalogues? - the bit's should cost cents not $$s!
Title: Tach
Post by: johnny on April 03, 2006, 08:48:24 am
Just for indication, the total costs of the parts for the rebuild were 5,- at a electronica store.
Title: Tach
Post by: KarmannSport on April 03, 2006, 12:39:25 pm
WESTMORELAND DONE - One small problem


I did the westmoreland 83 GTI tach conversion.  On fire up the thing is working perfectly.  Only problem is I cant adjust the idle any further down than 4k RPM.  When I rev it, it looks like its reving up correctly, but its idleing at 4k rpm so you get the problem.  

ANy ideas from the electro gurus?

Update...Once the revs hit a certain point the tach drops back off to like 4k rpm.

Im using a motorola alt with the W terminal.  This is all in an 81 pickup (not that that really matters)

If I adjust the trimmer (all the way down it will idle at 4k) it just goes up until what would be like 10K rpm if the numbers went that far, then it drops down to like 4k again.

FURTHER UPDATE:  Looking at the westy schematics compared to the TD ones...should whats labled as RV2 on the westmoreland schematics be a 47 nf cap, not a 220 nf cap.  Just comparing the two and noticed this.  I have the 220nf one in mine....could this be why the tach starts out at 4k rpm?
Title: yey
Post by: YoSono on April 04, 2006, 03:16:48 am
thanks to Herr Cheesemeister, i now have a set of fully working tacho clocks ;)

Just one thing though, both me n reg noticed that the 500 RPM line on the euro tacho face was a little high, as 0 rpm is actually 250RPM. I have adjusted this on the tacho face, and will gladly supply anyone with this update.

I've also taken a small video of the tacho working too... which you can see  HERE! (http://www.wearecentralpark.com/misc/gtd_tacho.mpg) you'll notice that i haven't put my dash back together yet also... as those clocks have been in and out more time than i can actually remember these past few weeks, lol.

one thing i have noticed, is that on startup, the needle dips for about 3 seconds, as the alternator charges up after the ignition... then it rises to its idle position - is this ok? like is this the characteristics of it taking its signal from the W TERMINAL?[/url]
Title: capacitors
Post by: fatmobile on April 04, 2006, 03:24:09 am
Yeah we have a local radio shack but I couldn't link to actual caps and see if you thought they would work.
 ....so they don't have to be electrolytic?
 I went to radioshack today and found a couple caps with the proper capacitance but they weren't electrolytic and radio shack is a spendy place.
 The ones on ebay are cents a piece, not dollars.
 I called digikey looking for them and they suggested this 16cent, 50v, .01uf (10nf) cap:
http://www.digikey.com/scripts/DkSearch/dksus.dll?KeywordSearch
picture of it:
http://rocky.digikey.com/WebLib/Kemet%20Caps/Web%20Photos/GOLDENMAX%20SERIES%205.33H,3.81L.jpg
data sheets:
http://www.kemet.com/kemet/web/homepage/kechome.nsf/vapubfiles/F3101EGoldmax.pdf/$file/F3101EGoldmax.pdf
 I'm going to root around on some of the circuit boards I've got laying around and see if I can find some free parts ... now that I know what I'm looking for.
Title: tach
Post by: fatmobile on April 04, 2006, 04:05:44 am
Quote
should whats labled as RV2 on the westmoreland schematics be a 47 nf cap, not a 220 nf cap.

 That looks about right.
 On the diesel tach there is a 47nf cap between pins 3 and 4 ... that's right where RV2 sits.
 On the gasser it's 220nf.
 It'll be ineresting to see what changing that cap does.
 
What are you guys using for R1?
 Yo sono, you are doing a motometer tach? From what year of car? That high 0rpm reading is when the car is shut off or with the ignition turned on but car not running ... or both? Not something that can realy be changed by circuitry?
Title: Tach
Post by: regcheeseman on April 04, 2006, 04:43:06 am
Karmann Sport,

You have some problems there, when the needle goes full scale and then drops back it, you have overloaded the chip past it's operational point and it's now dividing the signal by two and displaying that figure instead. You have adjusted the trimpot too far in the wrong direction.

However the 4K idle is an error in the circuit and will not be adjusted out by RV1. Johnny has a westmoreland working so I'm guessing it could be down to your build or a variation by westmoreland? EDIT - sorry Johnny's is a motometer so it is probably the circuit.....

Could you post a high quality component side photo for me?

Most of the caps are pretty unimportant value wise in the circuit however one controls the sampling time period as part of an RC network (RV1) and it's value is critical.

(edit. D'oh!  :oops: )

Yo Sono's clocks are VDO and built by yours truely, the time lag for the W term to 'come up' is quite normal and you may find it coincides with the charge light going out. It's a 'feature' of the altenator - not my circuit!
Title: Tach
Post by: regcheeseman on April 04, 2006, 04:58:56 am
Oh bugger  :oops:

The clue was in your question and fatmobile's answer, I just didn't spot it.

The single critical cap in this circuit is the one across pins 3 and 4 and it should be a 47nF.

The initial post was done in haste and has now been changed, all the other values seem fine.

Sorry!
Title: Tach
Post by: KarmannSport on April 04, 2006, 10:32:44 am
WESTMORELAND WORKS WORKS WORKS!!!!!  :D

That 220 cap at RV2 on the westy schematic was the problem.  Swapped it out for 47 and it brought the idle down from 4K rpm to 1K rpm.  SO now we know the differance.

So...for all that want to know...the westy schematic definetly works.  

If anyone has a large email account and wants the .PDF Of the gauge face I made let me know.  It has the redline set up for a diesel.

Thanks again to all that made this possible.  A diesel tach is a westy tach and a W terminal away for all of us in the USA!!
Title: Tach
Post by: regcheeseman on April 04, 2006, 10:58:25 am
Thats motometer, VDO and westmoreland sorted.

I dunno if this should be some form of sticky or something? But I could repost all the schematics together without all the guff in between....
Title: tach
Post by: fatmobile on April 05, 2006, 04:39:29 am
..so I started the "tach in the '91 Golf" project today.
 The dash is all torn up and this is the circuit board I pulled out:
(http://img214.imageshack.us/img214/9559/91board1xb.th.jpg) (http://img214.imageshack.us/my.php?image=91board1xb.jpg)
 I'm going to try to get a better picture somehow. The tach is just part of the circuit ... the part I circled.

 The first time I drew up the diesel schematics, I was just passing time and didn't do a very good job. I took some time to redraw the diesel tach with the chip flipped the proper way:
 (http://img232.imageshack.us/img232/9687/dieseldrawing6xx.th.jpg) (http://img232.imageshack.us/my.php?image=dieseldrawing6xx.jpg)
regcheeseman, you asked me if the resistor was supposed to be in parallel with RV1... what do ya know, it is. In this drawing I gave the resistor value and the measured value (because being in parallel changes the value) across RV1.
 The measured value was surprisingly close ... 8.2K diesel and 8.28k for the gasser.

Then I drew up the gasser schematic again:
(http://img80.imageshack.us/img80/4164/gasdrawing6yn.th.jpg) (http://img80.imageshack.us/my.php?image=gasdrawing6yn.jpg)
 R1 on this gasser tach is 6.8k, compared to 100 in the diesel. I got that wrong last time but I did some measuring this time.
Title: tach
Post by: fatmobile on April 05, 2006, 04:53:12 am
oh, and you also asked for a picture of the back of the diesel tach.
 Here's one that turned out Ok:
 (http://img229.imageshack.us/img229/1384/dieselback5fn.th.jpg) (http://img229.imageshack.us/my.php?image=dieselback5fn.jpg)
...and a repost of the populated side of the '85 Jetta Td circuit board:
(http://img51.imageshack.us/img51/7402/dieseltachcircuit2fw.th.jpg) (http://img51.imageshack.us/my.php?image=dieseltachcircuit2fw.jpg)
Title: Tach
Post by: regcheeseman on April 05, 2006, 04:55:35 am
A better picture like this? :wink:

(http://img90.imageshack.us/img90/7246/gtdpcb7ov.th.jpg) (http://img90.imageshack.us/my.php?image=gtdpcb7ov.jpg)

A bought a set of GTD clocks just to have a look... I followed the circuit until I got bored and cross-eyed. It is the same as the MK 1 conversion circuit pretty much.

Anyone want a set of GTD clocks in good condition?
Title: tach
Post by: fatmobile on April 05, 2006, 03:52:25 pm
Yeah, like that. You mentioned that you had been messing with one of these circuits. Good I don't have to try to capure a good picture of it now.
 
  ooops I remeasured the resistance measurement across the variable resistor and it's 81.6 for the gasser and 8.2k for the diesel.
 Resistance from pin 4 to pin 7 was 21.3k for the diesel and 15.6k for the gasser. Funny, the resistors used in this portion of the diesel tach were smaller but the end result was measured as higher than the gasser tach. I don't think any of the caps in this RC circuit need to be changed because it's adjustable through the range with what it has. Meaning R6 can stay the same and measuring for 21.3k should get you close to the desired result. ...as long as C5 (cap between pins 3 and 4) is 47nf.
 
 This post is getting long, it would be nice to put all the relevant data in one thread, keep comments over here and link the 2 posts ... or stick all the good stuff on the first page or something.
 
 Another cap question ... in the lower left of my new gasser tach drawing I posted the numbers of the cap that's stuck to pin 4. Is there any way to tell this cap's value from whats printed on it?

 regcheeseman, I am wondering why you have a cap from pin 1 to the positive stuff (C3). From the circuits I was just messing with, it looks like pin 1 has a better relationship to ground.
Title: tach
Post by: fatmobile on April 05, 2006, 08:17:46 pm
Ok, I google searched for cap values and got this page:
http://xtronics.com/kits/ccode.htm
 Looks like I am looking for a cap with a 103 on it if I want a 10nf cap... and 473 if I want a 47nf cap.
 Did I get that right?
 If so, it already has a 10nf cap that I can use. Just have to swap it in place of that 1k resistor that sits between pins 1 and 2.
Title: Tach
Post by: regcheeseman on April 06, 2006, 04:47:42 am
Spot on with the cap values - the 3 is a muliplier i.e. 'x10 to the power of - x'

C3 feature in all the tach circuits, I'm not going to argue with them - it'll be some form of noise elim/filter / decoupler , I'd guess....  :?
Title: tach
Post by: fatmobile on April 07, 2006, 01:10:26 am
I sure messed up the last drawing/schematic of the gasser tach. I missed a resistor.
 You asked me about R6 in some of the early PMs we traded.
 I thought it was in series with RV1 ... added to it. I was wrong.
 Like shown in my last diesel tach drawing, R6 is in parallel with RV1.
 I didn't understand why at first but now it makes perfect sense.
 Trying to make fine adjustments to a tiny 22K potentiometer is impossible. Putting a fixed resistor in parallel with it makes fine adjustments possible.
 For those that don't speak fluent electronics:
 If you put two 8K resistors in parallel (side-by-side with both ends connected to the same points, like R6 and RV1 in my diesel tach drawing) they will equal 4K. Now changing one of the resistors by 1000 ohms won't change the total output by 1000 ohms. I can't remember the formula but it would only change the total by about 500. So big changes in the 22k variable resistor (small movements of this tiny pot will make big changes in the value) are tamed by R6.
 I did another measurement of the resistance from pin 7 to pin 4 and got 21.3k. Thats the total resistance of the RV1, R6 (in parallel) and the 13k resistor added to it.
 When I went to adjust this resistance on my '91 Golf tach so it matched the diesel tach's, the adjustment was very fine. I was able to get it right on 21.2k, 21.4k or the 21.3k that it's supposed to be.
 I'll fix the gasser tach schematic/drawing and probably start a thread dedicated to the '91 gasser tach conversion and link to it here ... break this thread up a little so people can go to their application without having to read this whole post.
Title: Tach
Post by: regcheeseman on April 07, 2006, 04:27:50 am
Parallel resistor network of two resistors

(R1 x R2) / (R1 + R2) = Rtotal

for three or more...

1/R1 + 1/R2 +1/R3 +....... = 1/Rtotal


On a different note, I think most of my pictures are on imageshack and they will disappear soon.. any of the powers at be on here wanna help me out with some hosting.

I can redo a single thread with all the diesel conversion variations of A1 tach and the conversion instructions and the A2 variant with it's instructions.
Title: tach
Post by: fatmobile on April 07, 2006, 11:06:40 pm
I put everything back together and plugged it in ... nothing.
 I traced the wire from the alternator and it was hooked up right so I swapped a jumper in place of the diode on the input side of things and I now have a working tach in my '91 Golf (gasser turned into a turbo diesel).
 I drilled a hole in the front of my instrument cluster so I could adjust it while it's in the car. I ended up adjusting it all the way to the bottom end but I have rigged up a 90 amp, non-AC setup and used a slightly larger pully.
 It's close but I think it's reading about 500 RPM higher on the top end than it really is.
 I did some things different. Pin 1 is grounded and has a 10nf cap to pin 2.
 No C3 cap to positive power.
Pin 6 is grounded so there is no R4.
 R6 the parallel resistor is 5.2K.
 R2 is 82 ohm
 I'll draw something up and post it.
 Ha, I have a tach :D  8)
Title: Tach
Post by: regcheeseman on April 10, 2006, 04:24:13 am
I look out for your schematic, Not sure about somre of your changes from a functioning circuit.

The lack of adjustment is either down to the missing R4 or the your R6 change which is not a parallel - I think I know what you've done but R6 should still be present and it has to be in series  :?

Anyway it works.  :D
Title: tach
Post by: fatmobile on April 11, 2006, 03:48:21 am
Ok, you are right.
 There is still a resistor in series with RV1.
 I kept the 15k resistor that was there originally. I might swap it to the 13k value the diesel tach had, to see if I can get the adjustment to ride closer to the middle instead of bottoming out.
 I forgot we were going to name the parallel resistor something else... Rx?
 I almost have the corrected drawing of the original gasser tach done.
 I will show what I did but now that I understand the RC circuit better, I probably could have gotten by with fewer changes so I'm going to grab another instrument cluster from the '91 Golf they hold for me at the local salvage yard and do minimal changes then check to see what they did.
 
 On a side note... now my clock doesn't work, ha.
 Now I don't know exactly when I'm driving too fast :lol: but I know my RPMs.
Title: Tach
Post by: fspGTD on April 12, 2006, 05:11:45 pm
regcheeseman - I definitey agree that there is some new FAQ worthy material in this thread!

Feel free to go ahead and create a new thread in the FAQ section about tachometer conversions.  Feel free in addition to summarizing/condensing the most pertinent material contained in this thread, to include links to this thread and any other possibly useful, related threads.  Thanks!
Title: Tach
Post by: Mark(The Miser)UK on April 13, 2006, 08:42:42 am
Well done Reg
I never did dig out that osciliscope :(
 :D  All it took was someone with a little nouse...  :D
Who'd of thought that Cornwall could produce anything other than Pasties...

 :twisted: Now you're gonna cost the sensor sellers serious $$= :twisted:

All I have to say from here is

Ooooh Arrrrrh
 :shock:
Title: Tach
Post by: RabbitJockey on August 07, 2006, 09:21:32 pm
my late cabriolet cluster arrived today (fits perfectly into a mk1 jetta) so i started tearing into it, i thought it would be just like the vdo one in the faq, but mine is slightly different, here are pictures of both sides of the circuit board, any help is well appreciated
mine:
(http://img.photobucket.com/albums/v306/Trev0rbr/cbws.jpg)

(http://img.photobucket.com/albums/v306/Trev0rbr/cbps.jpg)


pictures from faq:

(http://195.194.142.37/content/m4444424/GasserPCBsml.jpg)
Title: Tach
Post by: RabbitJockey on August 07, 2006, 10:03:04 pm
actually, now that i have been looking, it appears that i may just be able to do more or less the same mods, well jsut try and make my board like the finished one for the similar but different tach.  i dunno though, it would be quite handy if someone who knew would give me a post, thanks for any help. :wink:
Title: tach
Post by: fatmobile on August 08, 2006, 03:51:37 am
I've been messing with another '91 tach I got.
 The first thing to do is make the input to the chip match the TD tach.
 The input comes into pin 2. Looks fom here like it goes to the little blue diode with the B7X on it.... swap that for a straight through jumper wire.
 That stuff is in the center. After that it's hard to figure out because the pics are too big for the screen and to look at stuff I have to scroll right, take a look, go down scroll left. Would be nice if all the stuff stayed on the same end of the board. Flipping it vertically would make it easier for me to follow.
 It kinda looks like the resistor above the greeny/blue blimp (cap), brown, red?, brown, light brown, light brown, BRBBB? is the one that needs swapped to 15k ohms.brown, green, orange.
 It's possible that the only other change would be swapping the big yellow box (resistor) in the lower right corner needs to be swapped with a cap that says 473 on it. (47 nf).
 Try that and see what happens.
 On my first tach I swapped out way more than was needed. On the last one I swapped a little more than just the diode and resistor on the input. That brown, black, red resistor got swapped for a cap. 10nf (103 on it). Not sure this needed done  because I was messing around with a 15k resistor on the tach side and changed too many things at the same time.
Title: Tach
Post by: RabbitJockey on August 08, 2006, 06:34:52 pm
(http://img.photobucket.com/albums/v306/Trev0rbr/cbpscircuit.jpg)
Title: tach
Post by: fatmobile on August 09, 2006, 04:25:01 am
(http://img225.imageshack.us/img225/9598/oddtach1tl5.th.jpg) (http://img225.imageshack.us/my.php?image=oddtach1tl5.jpg)
 The red line shows the path the input signal takes to get to the chip. That needs to be 15k ohms. Chuck the diode and swap a jumper in it's place.
 Change the resistor to 15k.
Title: Tach
Post by: regcheeseman on August 09, 2006, 04:49:50 am
(http://img66.imageshack.us/img66/7545/trev3wh7.jpg)

With reference to my final diesel schematic and the image above

Remove all components marked with red X

Replace D1 with wire link
Replace R10 with 10nF capacitor (C1)
Replace RV2 with 47nF capacitor (C5)
There is no provision to place capacitor C3 - Should work without but you may want to put one in if the needle is prone eratic behaviour.

(http://img95.imageshack.us/img95/2999/trev4yk4.jpg)
Title: Tach
Post by: RabbitJockey on August 09, 2006, 08:10:20 pm
accidentally touched the positive to the signal, but it wasn't grounded, but the signal wire was connected to the alternator, but the car was not on, i dunno if this could have blow it or not,... we'll see
Title: Tach
Post by: RabbitJockey on August 09, 2006, 08:39:37 pm
never mind i got it working and it's pimp, just need to actually get it into my car now
Title: Tach
Post by: RabbitJockey on August 09, 2006, 09:32:24 pm
yay

(http://img.photobucket.com/albums/v306/Trev0rbr/alldone.jpg)
Title: tach
Post by: fatmobile on August 10, 2006, 12:49:03 am
I don't know about having to remove the components with the red Xs.
 trevOrbr, what all did you change?
 RV2 isn't variable so should it have an R designation instead of the RV?
Title: Tach
Post by: regcheeseman on August 10, 2006, 04:31:29 am
Quote
I don't know about having to remove the components with the red Xs.


It works doesn't it?  :roll:

Quote
RV2 isn't variable so should it have an R designation instead of the RV?


Well actually.... looking at it again, it would appear to be a cap, so it should have a C designation?

Anyway, I'm doing this stuff at work, with boss in same room, running it in a small a window as possible, hidden amongest menus on my auxillary monitors whilst thinking about work and convincing my boss I am doing some - apologies for any mistakes.
Title: Tach
Post by: RabbitJockey on August 10, 2006, 08:31:20 am
i did everything i was told, and the first time i hooked it up it worked, i just had to adjusting the variable resistor a tad, and then i was golden, thanks for the help
Title: Tach
Post by: RabbitJockey on August 10, 2006, 10:08:15 pm
ok now that i've been driving i've been recording different rpms at what speed, then i went to scirocco gear up and checked the accuracy and heres what i have.  i did try and adjust it to get it at the right rpm anways

gear-speed-rpm-true rpm

2-20-2400-2231
3-30-2400-2225
4-25-1400-1308
4-40-2100-2093
5-55-2400-2245

seems a little inconsistent, i'll have to get someone to ride with me, it needs to be adjusted to have a little less sweep though, i'll mess with it tomorrow or this weekend, after all the driving i've done with out it though, it seems so useless since i already know where the power is at and stuff.
Title: Tach
Post by: jtanguay on August 10, 2006, 10:13:18 pm
lmao... unleaded fuel sucks! haha
Title: Tach
Post by: RabbitJockey on August 10, 2006, 10:18:14 pm
i wondered when someone would catch that haha
Title: tach
Post by: fatmobile on August 11, 2006, 03:20:58 am
Quote
Quote:I don't know about having to remove the components with the red Xs.
 
It works doesn't it?

 It works without removing them too.





Quote
Quote:
RV2 isn't variable so should it have an R designation instead of the RV?


Well actually.... looking at it again, it would appear to be a cap, so it should have a C designation?

 It's not a cap, it's a 22k resistor. It's one of the things that is common on all these different styles of gasser tachs. The 22k resistor that goes between pins 3 and 4. Someone earlier in this thread didn't swap it and the tach would only go to about 4k (I think).



Quote
i did everything i was told, and the first time i hooked it up it worked,

 Did you remove everything with a red x on it?
 
Eventually I want to figure out the fewest parts that need changed and what component(s) determines the rate of change.
Title: Tach
Post by: RabbitJockey on August 11, 2006, 11:58:49 am
i did everything he said, i dunno if it was all necessary as said, but it definetly works now, and its not like it takes long to do any of this work, took me more time to setup a board and a sponge and let my iron warm up than it actually did to solder all the pieces in and remove them
Title: Tach
Post by: RabbitJockey on November 25, 2006, 12:04:08 pm
has anyone else had any trouble converting the westmoreland tach conversion, i have made mine exaclty as the instructions said in the faq, accept for usinga 75 ohm in place of the 72 ohm, and my tach will not even move, and i have converting 2 and have the same problem on each, they don't work at all, can anyone help or suggest anything?
Title: Tach
Post by: Hillshy on November 26, 2006, 04:32:46 am
Hi TrevO,

if all else fails, i have an idea as this was the route i took in the end, i couldnt find a gauge that matched mine (caravelle) from the info on the prev posts,

find the picture below this post from reg:
Re-worked into diesel w terminal version,

i built the circuit on a small pcb, then mounted it in sealable plastic box(matchbox size) tapped into some power feeds, the wires to the tack and Alt terminal feed. its mounted 3 inchs away from the tach on velcro, i can get to it easy as i fine tune it, i made a small hole in the side of the box so i can adjust the pot to calibrate.

it works for me, althoungh not as neat as some or most who have managed to intergrate onto the existing board so it all looks factory, i tried to do the same but my clocks just didn't match any, it really wanted the tach hence took this option, never the less it works!

i hope this helps.

hillshy
Title: Tach
Post by: RabbitJockey on November 26, 2006, 10:47:20 am
that's actuallly something i was considering, but this is for someone else and not for me, and it has me befuddled because other people have gottent heres to work with the same changes... argh, i might just take and stick a board from a jetta/cabriolet into the westmoreland tach and see how that goes haha
Title: Tach
Post by: greendub on February 25, 2007, 10:01:16 pm
I've been working on my tach conversion for months (tinkering here and there), but my VDO tach is not the same as the one in the FAQ.  It's what I'm calling VDO style #2. The board and elements are similar to the tach that fatmobile posted at the beginning of this thread from his '85 TD.  Despite all my tinkering, I've come to realize that I just don't understand this electronics stuff as much as I need to in order to create the schematic for a diesel tach conversion for this tach style.  So, I'm raising my hand to those that know more than me.  I've posted my pictures in hopes that someone can lend a hand to outline what caps and resistors go where.  

My '87 Jetta gasser tach pics that I picked up on ebay:

(http://img526.imageshack.us/img526/1466/tachovdostyle2frontpm6.th.jpg) (http://img526.imageshack.us/my.php?image=tachovdostyle2frontpm6.jpg) (http://img237.imageshack.us/img237/3862/tachovdostyle2backmy2.th.jpg) (http://img237.imageshack.us/my.php?image=tachovdostyle2backmy2.jpg)

Btw, I've been reading this forum since July and the Jetta wouldn't be running without it.
Title: Tach
Post by: MikeyT on March 08, 2007, 03:41:27 pm
If you are interested in a external tach, I purchased one of these recently, and amazingly it works perfectly with my '90 1.6L, straight out of the box.

http://cgi.ebay.com/ebaymotors/SEA-RAY-SEARAY-BOAT-ALT-DIESEL-TACHOMETER-TACH-TELEFLEX_W0QQcmdZViewItemQQcategoryZ26455QQitemZ280073780873QQrdZ1QQsspagenameZWD1V

MT
Title: Tach
Post by: lusob on April 11, 2007, 06:45:51 am
Hi,
I have motometer with MFA. I read whole topic but i can't find solution for my tacho. My is totally other than all in this topic.
Here are photos of it:
http://img135.imageshack.us/img135/3138/0704111235pj7.jpg
http://img139.imageshack.us/img139/9611/0704111234jk6.jpg
I don't know how to make it for diesel.
Title: Tach
Post by: Xenington on May 14, 2007, 06:10:31 am
This is an excellent thread. Kudos to Cheesey, Fatty and all the other people involved.

I have a VDO aftermarket tach and have converted it to work off the alternator using the ideas posted here. It works great.

However I was wondering if it would be possible to take this idea and apply it to other vehicles, in particular Land Rovers.

The only difference between the two vehicles that I can see is the pulley size ratio (both alternators emit 6 pulses per alternator rev). The VW ratio is 1:2.38 whereas the LR ratio is 1:3.6.

Quote
This tach will work on the signal from the W terminal on the alternator
The Bosch alternator that i used gave 6 pulses on the W terminal and the ratio between the cranck and the alternator is 1:2,38. When you calibrate it do it on the higest RPM possible you get a better reading on lover RPM:s.


Quote
I've just re-read though and it may seem that the 25 pulse per engine rev quoted elsewhere may be a little excessive and 14.3 is nearer the mark....


This is quite a big difference (14.3 pulses per second in the VW compared to 21.6 in the LR).

Which component controls the pulses entering the circuit? Is it C5 - the capacitor between pins 3 and 4 of the SAK215? Is there a fomula for calculating the correct value for C5?

By the way, the big pink rectangular thing of earlier messages which was labelled RV2 is in fact a 220nF capacitor (= 0.22uF).

Cheers
Dean
Title: Tach
Post by: Hexar on September 05, 2007, 10:19:59 pm
Excellent information!

I have a 83 Turbo Diesel Rabbit that does not have a tach, I am thinking to add one, what options do I have? I read that there is no mk1 diesels with tach, is this correct?

I went to the junk yard, and all mk2 gassers have different tach, I mean, they have oil/water temperature meters at the bottom, the top of the tach is round.

On my rabbit, I have water temp on top, then in the middle is the huge clock, down in the bottom is the oil temperature gauge

If I use the method discussed in this thread, do I take the whole instructment panel off a gasser car, or I just take the tach only (including its niddle, indicator, display panel with number 0-7k) ?

If I only take the tach , then it will block my stock water temp gauge...

Sorry for being slow...

Thanks!
Hexar
Title: MK3 gas tach to diesel?
Post by: bigblockchev on September 05, 2007, 11:16:16 pm
Now if only someone had info re converting a MK3 gas tach to diesel I would be set. Cheers Dan
Title: Tach
Post by: 53 willys on October 25, 2008, 11:45:09 pm
Quote from: "lusob"
Hi,
I have motometer with MFA. I read whole topic but i can't find solution for my tacho. My is totally other than all in this topic.
Here are photos of it:
http://img135.imageshack.us/img135/3138/0704111235pj7.jpg
http://img139.imageshack.us/img139/9611/0704111234jk6.jpg
I don't know how to make it for diesel.


any body ever figure out this style tach for conversion??? I have this style(except mine is VDO with MFA) and would like to convert it...I bought a parts diesel cluster but it totally diffrent then my 91 gli with MFA cluster....I kinda wanna use the MFA if I can....I would also like the higher reading tach from the gasser cluster...
anybody??
(http://img135.imageshack.us/img135/3138/0704111235pj7.jpg)

(http://img139.imageshack.us/img139/9611/0704111234jk6.jpg)
Title: Tach
Post by: regcheeseman on October 28, 2008, 06:16:59 pm
Not a phreaking chance mate! Surface mount board, at least dual layer, you haven't got a hope in hell.

Is it from a MK3? If so why not buy a mk3 diesel clock set. They'd be cheap over here.
Title: Tach
Post by: zukgod1 on October 29, 2008, 10:40:31 am
Quote from: "regcheeseman"
Not a phreaking chance mate! Surface mount board, at least dual layer, you haven't got a hope in hell.

Is it from a MK3? If so why not buy a mk3 diesel clock set. They'd be cheap over here.


Nope he is working on a mk2
Title: Tach
Post by: regcheeseman on October 29, 2008, 06:27:57 pm
may I suggest a mk2 diesel tacho then..... :roll: