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electrical gremlins- pls help

Discussion in 'Technical Q&A' started by tifosi, Feb 29, 2004.

  1. tifosi

    tifosi F1 Veteran
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    #1 tifosi, Feb 29, 2004
    Last edited by a moderator: Sep 7, 2017
    I am trying to finally resolve some electrical gremlins that I have been chasing for the last couple of months. Here is how the issue developed on my 86 Mondial Cab

    When driving the radio, clock, windows would occasionally cut out, the car continued to run, and they would eventually come back on.

    Similarly I could be driving and go to turn on the headlamps and as soon as I would flip the lamps on I would loose the headlamps, and all the above items mentioned. The only electrical things that would continue to run would be the gauges, the engine (fuel pump), turn signals and brake lamps. If I tried to replicate this in the garage I could but if I ever so slightly touched the negative cable on the battery everything would return to working other than the headlights. Tapping or slightly moving the fuse box did not have any results.

    I replaced the battery and for several weeks the problem was gone, headlights and everything worked fine.

    The problem then returned and now the affected items generally tend to be inoperable as opposed to working when I am out driving the car. While it does not really effect my enjoyment of driving the car, I am fed up. I replaced all the fuses and the neg battery cable and no change. I pulled out the fuse box today and noticed some of the white wire harnesses have the typically “burn” marks, but none of the marks look particularly new. The box looks in good shape in the front with no corrosion on the male connectors into the harnesses. I pulled a few relays and they don’t look too bad either. Below is a pic of the back of the box, I am not sure what its is supposed to look like, most of the soder looks ok, a couple look a little brown. I would appreciate any thoughts on this and possible solutions, I don’t want to just replace the box and find the issue is really something else. Thanks in advance.
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  3. dm_n_stuff

    dm_n_stuff Global Moderator
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    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
     
  4. Nationaltec

    Nationaltec Karting

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    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
     
  5. thecarreaper

    thecarreaper F1 World Champ
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    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!!!
     
  6. enjoythemusic

    enjoythemusic F1 World Champ

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    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
     
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  8. tifosi

    tifosi F1 Veteran
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    thanks for all the good offers/ideas, unfortunately I am in NJ. As you can see from the pic some of the solder is shiney but others are brown/black. Maybe I can look to have it tested locally, not sure I would know how to resolder it myself. An additional stupid question, does the board in the pic seperate from the back of the box, there are addtional screws holding it but I was leary of taking them out. Am I correct in saying I will have to in order to get to the front of the board?

    Thanks again.

    Tom
     
  9. dm_n_stuff

    dm_n_stuff Global Moderator
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    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.
     
  10. tifosi

    tifosi F1 Veteran
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    thanks, I just spoke with a auto electrical shop and they said they would test the board for about 25 bucks, question is should I bring the whole fuse/relay box and board (which has a ferrari label on it) or just bring the back board? any tricks to removing the board from the box? other then the screws, what connects the two?
     
  11. enjoythemusic

    enjoythemusic F1 World Champ

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    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
     
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  13. tifosi

    tifosi F1 Veteran
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    Thanks steve, I will have them redo the solder for me, any tricks to getting the board out, other than the screws?
     
  14. Steve Magnusson

    Steve Magnusson F1 World Champ
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    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.
     
  15. tifosi

    tifosi F1 Veteran
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    thanks steve, is the bottom pic in your post the other side of the pic I am showing?
     
  16. Steve Magnusson

    Steve Magnusson F1 World Champ
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    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.
     
  17. tifosi

    tifosi F1 Veteran
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    thanks, one other thing, what are some areas to check for possible ground problems.
     
  18. Steve Magnusson

    Steve Magnusson F1 World Champ
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    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.
     
  19. tifosi

    tifosi F1 Veteran
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    I guess I was thinking more broadly of double checking the main grounds in the car to make sure they are not causing issues. I know where the radio and the amp are grounded but just wondering other areas to look for ground issues
     
  20. Chiaro_Slag

    Chiaro_Slag F1 Veteran

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    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.
     
  21. tifosi

    tifosi F1 Veteran
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    i plan on doing that, found a source about $3 a piece, That said some of the issues do not appear to be relay related - ie the clock
     
  22. Chiaro_Slag

    Chiaro_Slag F1 Veteran

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    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.
     
  23. tifosi

    tifosi F1 Veteran
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    I will post definately post the results - which I hope are positive, I have been quoted those prices, when I get them and everything goes smoothly I will post the source. I am waiting to hear back from them on 0-332-015-006. They said it would take an hour and that was this am
     
  24. tifosi

    tifosi F1 Veteran
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    I got the board out last night, I will bring it this weekend and report back
     

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