Why would someone scratch this circuit board

[bwmac]

I have been hunting for why my fuel gauge dose not work and at the same time fixing the engine leaks.

newly acquired car

So since the fuse for the fuel gauge is good and when I jumped the sender nothing happened, I removed the gauge cluster


What I found alludes me
I found scratch marks across one of the circuits like someone was trying to disable something




Anyone know what circuit this may be
and where I can get another circuit board #992.645.909
BTW this dam read-out is not in English, can it be changed

[JhwShark]

Wow, never seen this one...nice scrap job.

Sorry about what you have to deal with, it also looks like there is flux or some other compound (stain) on the circuit board. Someone may have tried to fix/break gauges...

Try 928 Intl for a board. If you have a good solder iron and have a good hand, you possibly could re-solder over the circuit. I would try to find a suitable replacement.

Mr. Merlin may have a magic wand.
Jon

[Mrmerlin]

Alan should be able to assist you with the circuit ID

[Normy]

These cars suffer from the fact that they were usually bought by people who weren't technical, and when something broke inside the warrantee, then they just took it to the dealership and had them fix it.

Then these cars were sold to people who were just the opposite: They were somewhat technical, but were no where near as wealthy as the original owners so they wanted the repair done on the cheap.

And those cheap repairs can haunt the current owners. It took me about 8 years to finally solve all the LH and EZF problems, and properly "dial in" my car. I'm not an automotive technician- I have a BS degree in aeronautical engineering from ERAU, and fly 727's for a cargo airline. I usually just work on my own car myself. In almost 11 years of ownership, I have only four times taken my car to a shop to have REAL work done, and two of those were timing belt changes done at Zotz Garage in Orlando, who's owner, Ron Zitza is a former president of the local PCA chapter.

In the end...that is really nasty looking! I don't know why anyone would scratch that pot that way~

N

[harborman]

I looks like some replaced a component where the solder flux is showing. I bet they then wanted to put power to the board and scratched that "+" mark to make better contact. They also scratched across those other wire paths. I would check those for continuity and maybe solder any broken connections. At least this is not "surface mount technology" like a lot of electronics today, then you need a microscope and special soldering tools to fix.

[harborman]

Originally Posted by harborman

I looks like some replaced a component where the solder flux is showing. I bet they then wanted to put power to the board and scratched that "+" mark to make better contact. They also scratched across those other wire paths. I would check those for continuity and maybe solder any broken connections. At least this is not "surface mount technology" like a lot of electronics today, then you need a microscope and special soldering tools to fix.

Upon a better look, this board is using some surface mount components. I would check the continuity on the leads that were scratched across. Who ever worked on this board were sloppy or did not know what they were doing. You need a good soldering iron made to repair this kind of board, with fine tips and controlled heat. I would take it to someone who has worked on boards like this and has the special soldering irons.

[MPDano]

Like harborman said, you can check the continuity of the circuits to see if they really did break the circuit. If you find one broken, by the looks of the circuit, you can do this easily with a fine tip solder iron, flux and solder and very small wire. Just follow the circuit line and solder at that point where the solder already exists. Looks difficult but really isn't.

For sure, Alan can ID what part of that Circuit does though.

[MPDano]

Here's the circuit path, just connect these if the circuit is broken. Do the other 2 if they are also broken.

[harborman]

Originally Posted by MPDano

Here's the circuit path, just connect these if the circuit is broken. Do the other 2 if they are also broken.

Make sure you use solder with flux in it for electronic circuits. Radio Shack has it. DO not use acid core solder. You can get the solder in different sizes and go with a thin one. When done use a magnifier glass to examine your work and clean with some tuner/electronic cleaner if necessary. Those circuit paths look close to each other so make sure you do not "bridge" any with solder. Good Luck!!!

PS. A good supplier of electronic components is Digikey in Minn. Big catalog,
all sorts of resistors, capacitors, chips, soldering tools, etc!

DigiKey Corp. | Electronic Components Distributor | United States Home Page

[MPDano]

Yeah, the circuit path is very thin at some points, but that's not where I would do my connections. See my diagram. Those are the points of connection.

[harborman]

Originally Posted by MPDano

Yeah, the circuit path is very thin at some points, but that's not where I would do my connections. See my diagram. Those are the points of connection.

Looks like he may have more than one path to contend with. Those scratches went over several paths it appears. A continuity test should do it. If in fact the original problem is there.

[bwmac]

I for sure will fix this one if all else fails and I don't need to send it for a core.
With it the only thing that didn't work was the fuel gauge.
I just wish I would have been able to diagnose it better but I have a lot of other stuff tore apart waiting for parts and i can't power it up.
Ya as an auto tech for many years i have had to fix a few circuits that way till the new parts came in. But All GM/chev

I was hoping someone might have a used north american modual as this display reads out in German
I asked 928 R us to see what they could find


BTW I found a loose bolt under the crossmember
Pulling the oil pan to do the bearings next

[anakilat]

In the old days (1988) I did mods on about 1000 computer motherboards for a company in Atlanta. We took some very fine, insulated wire and soldered it into the hole at the top of the connector trace (see MPDano's photo) and ran it directly to the component lead and soldered there as well. The trick is to make sure you have good mechanical connections before you solder, so use a solder sucker to clear the holes before you start.

Clean the flux with rubbing alcohol. When everything is clean, dry and cool put a spot of glue on the wire to hold it in place. You might want to take a needle and run it between the thin traces where they are scratched to make sure no debris is shorting them together.

I wonder if the previous repairs were made to calibrate a gauge?