ROG100

Chris,
I can email you some high res of the 89 board.
They are to large a file to post.
Let me have your email address by PM.
Roger

karl ruiter

If there is really need it may well be possible to reverse engineer/ and or modifiy this thing. Building a schematic from a PCB (even multilayer) would take an experienced engineer a few hours. Somebody who has never done it before should be able to do it in a day with a $4 voltmeter, as long as there are no BGAs and no potted parts. It is possible that there is a custom chip(ASIC) in there but I doubt it since the development cost of one starts at $1M and this was a low volume product and I dont think there is anything that could not be easily done with off the shelf chips. But then again it was probably designed by germans.
If a microprocessor was used (seperate, external program memory) it should be possible to read and duplicate it. I could be able to help with that if anybody wants to. However changing the soft without the origonal source could would be pretty hard. It would probably be easier to do new software from scratch...a big project, but perhaps a cool hobby for someone. If a microcontroller was used (on chip program memory) then it is likely copy protected and we will not be able to read it anyway.
On the subject of repair..isn't there sombody who repairs injection boxes as a small business/hobby? Likely they would be able to do these also, if there was demand for it.

ROG100

Karl,
My original "failed" PCB from my 93 GTS is with Rich Andrade.
He is "time permitting" looking at what you suggest.
Rich - I beleive - does the injection boxs.
Lets hope he comes up with a solution.
Roger

ColinB

Karl
You are probably thinking about the 928 enthusiast in England by the name of John Speake who has developed a high quality, more robust upgrade for the LH unit. There was an article on him in a recent 911 and Porsche World. 911&PW say we will all be needing his services eventually. He also produces a rebuilt/improved MAF and a diagnostic instrument similar to the Bosch hammer (and all at a fraction of the going price!) He's well aware of the instrument cluster situation but too busy right now with his other products. But I agree with you, this sort of work could probably be done easily by someone in the electronics field. Stand up please sir!

Colin 89GT

Chris

Well I could do it and add to the LH schematics on my website, but to do it I would need a PCB.

Chris

928mac

the cluster out of my 1989 import from Japan

tveltman

Holy thread resurrection Batman!

John Speake

THis is something my partner and I looked at some years ago. It's not so straightforward.....

Also, I rarely have requests for help on these units, other than to change the units display.

I assume that people are able to obtain replacment units from parted cars.

So not enough demand to warrant the development time.

captnkrunch

Great pix BWMAC! John has an economic point though. I think a useful intermediate step is just to document what we can of the board. I, too, am stuck with the correct way to install LED replacements for burned out bulbs. This sort of thing should be well known by now. I have the schematics for the wiring of my 89S4 but the symbols for various components are strange. Collectively, we ought to be able to corner these problems.

danglerb

I am SO GLAD I've started checking the date of the first post before I take an accidental history lesson.

Part of the problem is that the basic design sucks, four horribly wimpy non standard connectors, and an overall fragile circuit board. Even a brand new one is no long term assurance of proper operation.

The other part is that the failure may be in some other area, the spare tire well connector etc.

For me it past my frustration level, and I just live with a works sometimes speedo, but sooner or later a real fix needs to come along.

mjackson78

How screwed am I? No replacements are available for my 1982 printed circuit film. Can't seem to find anyone who knows how to repair either. I've traced it to damaged leads in the flexible printed circuit board/film. The damaged/missing conductive leads are worn off and/or damaged at each of the three connections on the back of the instrument cluster (...forgive me if I'm not using the correct terms, but I hope you can see what I need). Basically, it looks like I need some sort of glued-on(?) conductive metal that extends each of the leads so they wrap around the areas where they're missing. Seems like traditional soldering would quickly melt the flexible film.

928mac

Hang on there MJ, did you call Roger, did you call Mark at 928intel.
I am sure someone will have one, but you may need to wait a wee for them you notice your post.

SQLGuy

I've successfully soldered jumper wires over broken connections on a flexible PC board before... even in things as small as digital cameras. It's tricky, but doable. Worst case, it should be possible with your board too.

Another possibility is paint on trace repair stuff and copper trace foil:


So, you could apply the foil to make up for the part of the trace that goes around the curve, and use the paste to "cold solder" it to the original trace.

brianrheffron

This thread is way above my head but would this product
be of any use. It claims it can be used to repair PCBs.

http://www.frost.co.uk/automotive-el...connector.html

SQLGuy

Main question would be how flexible it is. It should provide similar capability to the paste I mentioned. If it's not flexible once cured, though, you'd still need jumper wire or copper foil to handle the part that goes around the bend.

I would most likely approach this type of repair with a thin 700 degree F iron tip (maybe even colder, but 700 is usually what I use for lighter work), an X-Acto knife (to scrape off any plastic or laquer over the traces to be repaired), and some wire wrap wire. I'd make jumpers from the wire wrap wire to go around the bend in the flex PCB, and solder them to parts of the traces on the flat areas. If the traces are cleaned and tinned, a good flux core solder is used, and the jumper ends are also tinned, it should be possible to do the actual soldering of jumper to trace quite quickly - minimizing heating of the plastic.