VWDiesel.net The IDI, TDI, and mTDI source.

Engine Specific Info and Questions => IDI Engine => Topic started by: Rabbit79 on January 22, 2017, 02:36:13 am

Title: Printed circuit repair
Post by: Rabbit79 on January 22, 2017, 02:36:13 am
Has anyone ever attempted to repair the printed circuit that goes on the back of the dash instrument cluster? If so how did you do it and how did it hold up? Mine has a break in one of the conductors and I was thinking I might be able to solder a couple strands of wire in there, but I'm afraid that thing might be a bit too delicate to withstand the heat of a soldering iron. So if you have a better plan..... let me hear it. 
Title: Re: Printed circuit repair
Post by: Spokerider on January 22, 2017, 10:48:33 am
I've been researching replacement of stepper motors on you tube, as the one/s on my 95 golf cluster are not working. Also saw lots of you tube posts on soldering the vw clusters. Try a search on you tube and see what comes up.
Title: Re: Printed circuit repair
Post by: oblique on January 22, 2017, 01:35:09 pm
If the copper trace had cracked you can easily bridge it with some solder but there wouldve been an initial issue that caused this. You can reinforce the board itself with some hot glue and then repair your trace. If youre talking about repairing the ribbon thats a bit more difficult as the heat may melt it. I do believe there are conductive epoxies out there for your wire strand idea.
Title: Re: Printed circuit repair
Post by: ORCoaster on January 22, 2017, 02:38:21 pm
What works best for me is a not so hot soldering iron.  They do make variable resistance ones but most you just have to be gentle, fast and not linger on the task.  You can cut some loose fine wire and solder over the crack but maybe your eyes are not as good as mine to keep it all lined up.  I do use a magnifier on some tasks like this and work in a very still environment. 

I like the epoxy idea if that is available.  You could trace the ribbon easily under magnification if the tip of the tube/pen/needle was fine enough.

I might even try cutting a longer wire than needed and epoxy in place then come back and touch it with some solder to be sure it was connected electrically to that ribbon.
 
Title: Re: Printed circuit repair
Post by: TylerDurden on January 22, 2017, 04:40:57 pm
Depending on where it is terminating on the cluster, you can solder a wire from the connector directly to the termination point.

In the flex pcb, I prefer a hot but small soldering tip... get in and out fast to avoid melting.
Title: Re: Printed circuit repair
Post by: RustyCaddy on January 22, 2017, 05:05:30 pm
One type of conductive epoxy is used to bridge breaks in rear window defrosting strips. It use to be pretty widely available.
Title: Re: Printed circuit repair
Post by: libbydiesel on January 22, 2017, 10:31:20 pm
I've used a CircuitWriter pen on the cluster printed circuits successfully several times. 
Title: Re: Printed circuit repair
Post by: Rabbit79 on January 24, 2017, 12:03:19 am
This actually ended up being easier than I thought it would be. I followed Spokerider's suggestion and checked out some circuit board repair videos on youtube, couldn't find anything specific to VWs, but there were plenty on just general PCB repair. I was missing about an inch or so of conductor, so I pulled out 2 strands from a piece of 10 gauge wire and twisted them together. The broken spot is right where it makes a loop around a screw, so I had to shape the wire to fit into that spot, then I taped it in place. When soldering I put the solder on the connection of the wire and the circuit trace and then came in on top of it with the soldering iron, just long enough to get the solder to melt. Worked like a charm. All that's left is to seal over it with some epoxy, which I don't happen to have any so I'll have to get some tomorrow. Thanks for the help everyone.

Edit: I used liquid electrical tape to seal over the repair. I figured if I ever have to go back in there to fix it again the liquid electrical tape will be easier to scrape off than epoxy.