electrical gremlins- pls help

I chased a similar problem in my 911.

Eventually, we discovered a very small fracture in the circuit board that was under the fuses.

I'm wondering, does it take a little while for the problem to occur, or is it almost immediate? We found that as the car ran, and electricity, or even the heat of summer, caused the board to expand, then the circuit would "break" and certain electrical components associated with that circuit would no longer function.

We replaced the board, and the problem went away.

Another possible problem could be a loose connection for a fuse or relay. Have any jumpers been added to the fuses to provide power to non standard equipment? That can cause the fuse to work loose. Also, if non standard equip. was deleted, and unwired from the fuses, that can make the prongs on the fuse socket loose, and cause intermittent problems.

Finally, hard to tell if a relay is getting stuck in the open position by just looking at it. IF you have some identical relays, swap them around and see if the problem moves with the relay.

Good luck, electrical is always the toughest to solve for me.

Dave

 

Tom,

It appears to be a single layer PCB, so I would suggest looking at it under a high-power microscope.

Micro-scopic "Metal migration" and or "cracked/cold-solder" joints could be a source of intermittent conditions based on your temp/hum.

I'm not sure of your locaton but I have such equipment to test/repair if needed. ( I'm in San Diego). It would on take a few minutes... No charge for a fellow F-chatter of course...!

One possibility is finding someone with a "Known Good" board (relays included) and then I can take a "Digital Profile" using a robotic prober system. Once a good master profile is created, future tests can be done hands-free within minutes for all f-chatters.... (this will even verify the relays).

Let me know,
Patrick

 

THIS IS ONE OF THE " COOLEST" TECH POSTS I HAVE SEEN. that is a great way to test and map the boards, 3 cheers for you offering to help the others out!!!

 

Hi,

Have done much more than my fair share of soldering (and have worked for Heathkit). Looking at the board, some of the solder joints are shiney (good) while some others look very dull or near black (bad). If it was me, and i have TWO Weller WCC100 temp controlled soldering guns and silver content (lead free) solder, i would be resoldering the board.

Basically, you use some flux and "sucker" or "wick" and remove the old solder. Then you resolder the joints. DO NOT use just ANY soldering gun as you MUST find the right temperature for the solder/board. Thgis is why both of my guns are temp controlled. TOO high a temp can melt the board, too low and you get what is called a "cold solder joint". Both are BAD BAD BAD. There are LITERALLY books written about how to solder.

Alas, am not a good teacher so please don't ask me to go into details about proper soldering. In the end you want to heat THE WORK (wire, joint, etc) and not the solder per se.

Enjoy the Drive,

Steven R. Rochlin

 

Yep.

Those screws would have to be removed in order to free the board from the box.

I'd suggest that you could take the board to a good TV repair place that still actually fixes TV's and doesn't just toss them out. They could fix up that board, at least repair the bad joints and see if it fixes the problem.

If you're in South Jersey, I know a stereo and TV repair shop in the suburbs of Philly who could do the work.

Probably an hour's work, maybe $100.

Good Luck.

 

Just the board, but personally i can SEE from the low rez pic there are solder problems. i would just go ahead and redo the solder. But that is me.

Enjoy the Drive,

Steven R. Rochlin

 

I think it's a multi-layer board (not a huge number -- like 3 or 4 conductor layers), but try to minimize flexing during removal/reassembly -- it's probably a crisp little cookie in a few areas . The upper portion of the jpeg shows the front side of the similar construction TR fuse/relay board. No active components just a lot of male tabs for the wired connectors and female spades for the relays/fuses.

You just have to unplug the relays and remove the screws to disassemble. The only thing a little tricky is that when you reassemble you've got to ensure that the free ends of the female spades are captured correctly in their respective supporting box features on the cover side.

 

Not quite exactly, but it is the same component -- the bottom part of the jpeg I posted shows the inside surface of the front cover (whereas, if you flipped over the whole assembly as shown in your jpeg you'd see the outside surface of the front cover).

PS -- the wires shown in the jpeg I posted I added to solve some problems I had with my fuse/relay board so you can ignore those.

 

Tom -- Not sure that I fully understand your "ground" question. The fuse/relay panel is mostly a +12V distribution system -- there is a small ground network on the fuse/relay panel itself, but it's only used for passing current thru the actuating coils inside of the relays. This ground connection will be brought to the fuse/relay panel ground network by one (or maybe two) of the wires connecting to one (or two) of the male tabs.

 

Have you replaced any of the relays? Last month my headlights would go on, but would not pop up. Turned out to be the low beams relay.

 

Good point - The clock wouldn't be relay.

Where did you find them for $3? I bought 3 recently at about $10 each or so.

I took the board apart also with another F-Chatter - Looked more complicated than I knew what to do wtih - Best of luck! Would be interested in hearing your results.