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Thread: General Module successful repair #2

  1. #1
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    Talking General Module successful repair #2

    Special thanks to ah1cobra for spurring me to finally do this. Same electrical issues: door locks, trunk, windows, interior lights, etc. didn't work in the morning if it was cold. Took it to dealer with general module information from this forum and they DENIED it was the general module. Half a dozen shop guys there said it was the relay module, which they replaced for $450 parts and claimed they tested for 4 days. By chance I picked up the car on the coldest day of this year in S.Cal. (frost on the roof) and nothing worked just like before. Drove the car home and everything worked by the time I hit the driveway. Ordered the capacitors on line from www.Newark.com for about $6 and they arrived two days later. Pulled the general module (my 1995 840ci has the cartridge holder under the left side of the dash and removing two nuts on the bottom edge allows it to swing down enough to get the modules out), replaced the capacitors and everything is working great. Photos in ah1cobra thread were very helpful.

    The five capacitors from BMW have axial leads and are rated at -40C to +85C.
    10 microFarads at 63 V
    1 microFarad at 63 V
    47 microFarads at 25 V
    100 microFarads at 25 V
    470 microfarads at 40 V

    I replaced them with capacitors rated at -40C to +125C and with a higher voltage rating for the lower ones. These were a little larger than the stock versions, but fit fine. Probably last forever now.
    10 microFarads at 63 V
    1 microFarad at 63 V
    47 microFarads at 50 V
    100 microFarads at 50 V
    470 microfarads at 50 V

  2. #2
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    Thanks for this post, what an easy fix. electrolytics typically have a 10 year operational life...and most probably less than that in an automobile application where summer temperatures and vibration can decrease their service life.


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  4. #4
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    koenig d: £140 for a general module that is probably not even refurbished? Besides, why pay for used or new if you can repair it almost for free...

  5. #5
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    Great repair, well done!
    Timm..2007 E64 650i Individual Sport..1999 E31 840ci Individual Sport..ex owner of 2000 E38 740..1999 E38 740i V8 M62..1998 E38 735i V8..1993 E32 730i V8..1988 E28 518i


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  6. #6
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    Would the climate control fall into this catagory???

  7. #7
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    please share part numbers of the caps

    mind sharing the part numbers from newark...don't want to order the wrong ones thanks!

  8. #8
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    Quote Originally Posted by german wannabe View Post
    mind sharing the part numbers from newark...don't want to order the wrong ones thanks!
    What do you mean "part numbers"?
    Go to your local electronics supply house and ask for the following:

    • 10 microFarads at 63 V
    • 1 microFarad at 63 V
    • 47 microFarads at 50 V
    • 100 microFarads at 50 V
    • 470 microfarads at 50 V
    '93 850Ci - Mineralweiß Metallic

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  9. #9
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    Make sure they give you axial capacitors.

  10. #10
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    Glad to post the Newark Part numbers and some hints on the replacement procedure.

    www.newark.com
    Aluminum Electrolytic Capacitors, Axial
    Newark Part Numbers:
    #97C7972, 10 microFarads at 63 V, $1.14 each
    #14M8286, 1 microFarad at 63 V, $0.852 each
    #97M4027, 47 microFarads at 50 V, $0.163 each
    #75K6216, 100 microFarads at 50 V, $0.182 each
    #79R7674 470 microfarads at 50 V, $0.832 each

    Plus shipping. As I said before, they're a little larger than the stock ones, but fit in fine. There's lots of room away from the board and you just place the four that go together side by side.

    Remove the old capacitors by placing a hot, tinned soldering iron on one of the capacitor leads AND the pad below and use a pair of needlenose pliers close to the capacitor body to pull the lead out of the board. Pressure on the pad keeps you from ripping the solder pad off the board while you pull the capacitor lead out. If your iron is hot enough and you make good contact with the lead and pad, it doesn't take much force to pull out the lead. Repeat for the other lead to remove the capacitor. I then used a vacuum desoldering tool from Radio Shack to get the residual solder out of the hole (heat the pad with the soldering iron and then suck out the liquid solder). You can use solder wick too, which is copper braid that you just press against the hole with the iron on the back to melt the solder and wick it out. Then bend the axial leads sideways on the capacitor, slip them in the two holes (being careful to get the polarity right), resolder by heating each lead and the pad while you apply the solder, and then trim the excess lead off on the back side. Be sure to check that you made the solder flow down the lead so that it also wets the pad on the backside of the board. You can apply a little solder to the back side to fill it in if you need to. The board has some comformal coating on it that you can scrape off the pads if you want with an exactoblade, although the soldering iron does a good job removing it.

  11. #11
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    i had the same issue with my GM, fixed it and everything works perfect excluding the sunroof... rechecked all capacitors n solding but its fine.
    my GM is not the cars original one... n i heard i need to reset it so all functions work... can u guys tell me how to do that


    thanks

  12. #12
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    Quote Originally Posted by zonixx View Post
    i had the same issue with my GM, fixed it and everything works perfect excluding the sunroof... rechecked all capacitors n solding but its fine. my GM is not the cars original one... n i heard i need to reset it so all functions work... can u guys tell me how to do that
    The A1 general module (GM) must be coded to your car's ZCS (central coding key). For this you will need a BMW diagnostic system (BMW NCS Expert or BMW Progman/SSS). Alternatively you can ask a BMW dealer to recode the module.


    PS: please stick to one topic instead of posting the same question in multiple topics

  13. #13
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    Quote Originally Posted by revtor View Post
    The A1 general module (GM) must be coded to your car's ZCS (central coding key). For this you will need a BMW diagnostic system (BMW NCS Expert or BMW Progman/SSS). Alternatively you can ask a BMW dealer to recode the module.


    PS: please stick to one topic instead of posting the same question in multiple topics
    thanx for the help revtor n sorry for the multi posts.... my bad

  14. #14
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    Does anybody localy do this? MAX, Wuffer? I suck @ circuit board stuff.

  15. #15
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    I've done a few of them, but I'm not local. If interested in mailing it out for a few days, PM me.

  16. #16
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    Quote Originally Posted by dgoebel View Post
    Glad to post the Newark Part numbers and some hints on the replacement procedure.

    www.newark.com
    Aluminum Electrolytic Capacitors, Axial
    Newark Part Numbers:
    #97C7972, 10 microFarads at 63 V, $1.14 each
    #14M8286, 1 microFarad at 63 V, $0.852 each
    #97M4027, 47 microFarads at 50 V, $0.163 each
    #75K6216, 100 microFarads at 50 V, $0.182 each
    #79R7674 470 microfarads at 50 V, $0.832 each

    Plus shipping. As I said before, they're a little larger than the stock ones, but fit in fine. There's lots of room away from the board and you just place the four that go together side by side.

    Remove the old capacitors by placing a hot, tinned soldering iron on one of the capacitor leads AND the pad below and use a pair of needlenose pliers close to the capacitor body to pull the lead out of the board. Pressure on the pad keeps you from ripping the solder pad off the board while you pull the capacitor lead out. If your iron is hot enough and you make good contact with the lead and pad, it doesn't take much force to pull out the lead. Repeat for the other lead to remove the capacitor. I then used a vacuum desoldering tool from Radio Shack to get the residual solder out of the hole (heat the pad with the soldering iron and then suck out the liquid solder). You can use solder wick too, which is copper braid that you just press against the hole with the iron on the back to melt the solder and wick it out. Then bend the axial leads sideways on the capacitor, slip them in the two holes (being careful to get the polarity right), resolder by heating each lead and the pad while you apply the solder, and then trim the excess lead off on the back side. Be sure to check that you made the solder flow down the lead so that it also wets the pad on the backside of the board. You can apply a little solder to the back side to fill it in if you need to. The board has some comformal coating on it that you can scrape off the pads if you want with an exactoblade, although the soldering iron does a good job removing it.
    Hi, So my Caps came in from Newark. Does anyone know which direction is postive on these caps? I have a feeling it's the shiny side besides the arrow point that way too, but before I solder these home I thought I'd ask.
    Attached Images Attached Images

  17. #17
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    Arrows point to the negative (-) end

    Grooved end is positive (+)


  18. #18
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    Revtor, I replaced mine from one I bought on ebay and everything works fine. What coding are you refering to?
    97 840ci-99 540i6-90 535i5 all black

  19. #19
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    Bluesman: Sunroof, headlight washers, wiper pressure adjustment,...

    For example, if your car is equipped with sunroof and headlight washers, but you replace the A1 general module (GM) with one from a car without these options, yours will no longer work either. Simply recoding the GM to the car's central coding key (ZCS) fixes these issues. Of course, there isn't a problem if the car you took the GM from had the same coding as your car.

    This may be less of an issue in the USA where the coding diversity is much smaller than elsewhere in the world.

  20. #20
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    Thankyou,that must be the case as everything works as it should.
    97 840ci-99 540i6-90 535i5 all black

  21. #21
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    OT: The power supply in a Dell Vostro desktop quit powering on a few weeks ago. Fortunately, it was cyber monday, so new power supplies could be had pretty cheap.

    Today, after the power supply marginally passed the paperclip jumper test (LED went out briefly), I pulled the cover off the Hipro 300W power supply to find the 2200uF capacitors bulged and dried up..

    EDIT: Paperclip test is to grab the ATX connector, jumper the green (PWR-ON) wire to one of the black ground wires.. This fires up the power
    Last edited by EEDegreeToDrive; 12-12-2011 at 05:51 PM.

    '89 735i, '91 850i, '81 MB 380SLC (For Sale), Tesla Model 3, and VW Passat TDI -- Yes, I still repair General Modules, DM for info!

  22. #22
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    This is great information, as I'm looking to give this a try (stuff not working in the cold is driving me crazy) Does a more detailed writeup exist other than "get these capacitors and replace them where you see them on the board?" Do I need a more detailed writeup? (I haven't pulled the module yet) Many thanks for this info, guys.

  23. #23
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    Quote Originally Posted by Spandrel View Post
    This is great information, as I'm looking to give this a try (stuff not working in the cold is driving me crazy) Does a more detailed writeup exist other than "get these capacitors and replace them where you see them on the board?" Do I need a more detailed writeup? (I haven't pulled the module yet) Many thanks for this info, guys.
    It's about that simple-

    However:
    1) Make sure the polarity matches the diagrams
    2) Use a hot/temperature controlled soldering iron; Not a $5-15 radio shack gadget. Invest in a $50/used $100 new soldering station; You'll use it for other BMW repairs.
    3) Be careful when removing the old caps, you don't want to pull too hard and damage pads/traces
    4) Be careful when reinstalling the new capacitors; I reworked one forum members GM that had a capacitor installed in the wrong place, and had a solder bridge a bad place.

  24. #24
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    Quote Originally Posted by EEDegreeToDrive View Post
    It's about that simple-

    However:
    1) Make sure the polarity matches the diagrams
    2) Use a hot/temperature controlled soldering iron; Not a $5-15 radio shack gadget. Invest in a $50/used $100 new soldering station; You'll use it for other BMW repairs.
    3) Be careful when removing the old caps, you don't want to pull too hard and damage pads/traces
    4) Be careful when reinstalling the new capacitors; I reworked one forum members GM that had a capacitor installed in the wrong place, and had a solder bridge a bad place.

    Thanks! - Caps on order, we'll see how well I execute the repair soon.

  25. #25
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    Quote Originally Posted by Spandrel View Post
    This is great information, as I'm looking to give this a try (stuff not working in the cold is driving me crazy) Does a more detailed writeup exist other than "get these capacitors and replace them where you see them on the board?" Do I need a more detailed writeup? (I haven't pulled the module yet) Many thanks for this info, guys.
    All I can advise is remove the knee bolster, it'll make removing the GM sooooo much easier. There are several write-ups about it, should find them fairly easily searching.
    I'm not saying you're stupid, I'm saying you have bad luck at thinking.

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