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Author Topic: Gas Tacho / Revcounter Conversion to Diesel W terminal  (Read 132107 times)

Reply #120October 25, 2013, 12:56:18 pm

srgtlord

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #120 on: October 25, 2013, 12:56:18 pm »
Unfortunately the only picture I have is the one I posted and the tach is currently installed in the car at the moment :(  When I go to calibrate the tach Ill pull the tach out of the cluster to get another look at the part number but this probably wont happen until spring.....

Reply #121October 25, 2013, 01:19:23 pm

RabbitJockey

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #121 on: October 25, 2013, 01:19:23 pm »
thats fine, i'd just like to see what it is eventually, i couldn't find a replacement for the 215 chip found in older tachs.
98 Pontiac Grand Prix GT:stock daily
 81 Jetta: in progress 1.6td, ported head, holset turbo.
81 Rabbit:AAZ, hybrid T3 turbo, Giles pump, lightened fw, and yellow clutchnet clutch.

Reply #122October 25, 2013, 02:37:40 pm

srgtlord

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #122 on: October 25, 2013, 02:37:40 pm »
As a side note I found a picture of a moto-meter tack that has *drumroll please* the chip with the same part number


Reply #123November 20, 2013, 02:39:37 am

DraQuTzU90

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #123 on: November 20, 2013, 02:39:37 am »
this is to convert a cabriolet motometer tachometer into a vw diesel tachometer

board with tracks drawn on to it (i'll add proper parts lables soon):



Original diagram i drew to make it easier for me to understand to convert it:



and i took my diagram and used to figure out how to make the cabby board match this:



directions

1. replace d1 with a jumper wire
2. remove r2 and r3
3. replace r1 with a 15k ohm resistor (you can use the original r7 for this)
4. replace r4 with 191 ohm resistor (i used 2 100 ohm in series)
5. replace r7 with 10k ohm resistor
6. replace c1 with a 10nF capacitor
7. replace c2 with a 47nF(.047uF) capacitor
8. replace c3 with a 47uF capacitor (i used electrolytic how ever i just realized that i only removed c3 and the tach still worked when i tested it, so i am going to guess it is only there for filtering because it goes from the signal input to ground, replace it anyway just to be sure)
9. replace c4 with a 3.3uF capacitor (i used 3 10uF capacitors in series)
10.  calibrate!!!! i usually put the pot on the end of a long wire that way i can fully install the cluster and then adjust the tachometer as i drive, and then when i am finished tuck the wire away neatly behind one of the dash blanks
11.  enjoy your accurate fully functioning factory appearing diesel tachometer

Hello, I'm trying to build a board from 0 with sn29736p chip like yours with the diagram that you posted earlyer but it doesnt work, please can you post here your final diagram? maybe i dont do something right. It's the second time i try to build that board and still doesnt work.

Reply #124November 27, 2013, 02:25:58 pm

RabbitJockey

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #124 on: November 27, 2013, 02:25:58 pm »
what u see is what i did, and it did work, have you tried replacing the caps again??  have you played with the potentiometer?
98 Pontiac Grand Prix GT:stock daily
 81 Jetta: in progress 1.6td, ported head, holset turbo.
81 Rabbit:AAZ, hybrid T3 turbo, Giles pump, lightened fw, and yellow clutchnet clutch.

Reply #125January 16, 2014, 12:20:12 am

8v-of-fury!

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #125 on: January 16, 2014, 12:20:12 am »
Interesting to see that you-tube video up there of the ECU perfectly running the older style tach. One day, maybe when I do an E-TDI swap.. this will be beneficial ;)

Reply #126September 19, 2014, 11:22:31 pm

TimpanogosSlim

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #126 on: September 19, 2014, 11:22:31 pm »
Just did this mod to an 83 jetta gasser tach i pulled out of the junkyard today. Went pretty well. Had to tack the 10nf to the back of the board because what i had was 7mm spaced trimmed leads.

Had to parallel a 390 and a 360 to get to 191-ish ohms. Sorted and tested until i had 189.6 ohms so within 1%, should be fine.

'course the car isn't running yet, so . . . .
 

Reply #127September 29, 2014, 11:35:10 pm

TimpanogosSlim

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #127 on: September 29, 2014, 11:35:10 pm »
In case anyone was reading - my bentley manual says that the W terminal should connect to C11 on the fuse/relay panel in 83/84 rabbit/jetta diesel what came with the tach from the factory.

Has anyone tried this?

I have a thing about doing things the right way when i have some clue what that way is. So I'd like to try it. If it's likely to work.

Reply #128November 04, 2014, 01:35:07 am

TimpanogosSlim

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #128 on: November 04, 2014, 01:35:07 am »
FWW, although my wire harness already plugs into the W terminal (probably for the "shift up you dummy!" light in the cluster), my modified tach isn't moving.

since i got it at a junk yard, I have no way of knowing whether it worked before i modified it.

EDIT: It does work, intermittently. I have reason to believe that it's really my alternator that is intermittent, unfortunately.
« Last Edit: November 07, 2014, 11:48:13 pm by TimpanogosSlim »

Reply #129November 10, 2014, 08:53:48 am

srgtlord

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #129 on: November 10, 2014, 08:53:48 am »
I wonder If you have a loose connection somewhere. It might be beneficial to run a lead from your tach to the alternator w terminal

Reply #130November 14, 2014, 05:05:28 am

Kraftwerk

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #130 on: November 14, 2014, 05:05:28 am »
So, I have a CE1 (2 connectors) VDO gasser tach out of, I think, '86 Jetta, and I'd like to try to make it work in my '87 Passat diesel.
Diesel tachs are impossible to find, and since this one is going to spin a little higher, 5k tach wouldn't do it anyway.

So, anyone knows what should I do to this, which schematics work, etc? I have a friend who is an electrical engineer, but I have to give him something to start with...

http[TACH IMAGE]://[REMOVE THIS]s26.postimg.org/c84i1wbi0/IMG_20141113_200330.jpg
D24TIC power!

Reply #131November 26, 2014, 07:04:31 pm

libbydiesel

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #131 on: November 26, 2014, 07:04:31 pm »
Here's the missing pic from the first post.



In the text following the pic I'm not sure what the "zener" is, the pic doesn't show a C2.  Is it the white component bottom left?
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California

Reply #132November 28, 2014, 12:40:59 pm

RabbitJockey

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #132 on: November 28, 2014, 12:40:59 pm »
c2 i would also guess i the large white compnent on the left.  the zener must mean a zener diode, which i would guess is the component at the bottom right, since its the only thing that looks like a diode.
98 Pontiac Grand Prix GT:stock daily
 81 Jetta: in progress 1.6td, ported head, holset turbo.
81 Rabbit:AAZ, hybrid T3 turbo, Giles pump, lightened fw, and yellow clutchnet clutch.

Reply #133November 28, 2014, 01:00:07 pm

libbydiesel

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #133 on: November 28, 2014, 01:00:07 pm »
After posting I realized that board is the exact same as the one you posted in reply 100 and quoted by DraQuTzU90 above.  Your pic shows that C2 is the white capacitor.  I also agree that the 'zener' is the D1 diode in the bottom right. 
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California

Reply #134November 28, 2014, 01:07:16 pm

RabbitJockey

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Re: Gas Tacho / Revcounter Conversion to Diesel W terminal
« Reply #134 on: November 28, 2014, 01:07:16 pm »
After posting I realized that board is the exact same as the one you posted in reply 100 and quoted by DraQuTzU90 above.  Your pic shows that C2 is the white capacitor.  I also agree that the 'zener' is the D1 diode in the bottom right.

looks like it's even labeled as a z on that board.  and what ever i wrote for that boards instructions definitely worked, looks like someone else had already figured it out, but i couldn't see the picture so ended up writing my own up.
98 Pontiac Grand Prix GT:stock daily
 81 Jetta: in progress 1.6td, ported head, holset turbo.
81 Rabbit:AAZ, hybrid T3 turbo, Giles pump, lightened fw, and yellow clutchnet clutch.

 

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