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Thread: sword repair archive

  1. #1
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    Default sword repair archive

    My collection of info, pls add any new info/links
    http://www.bimmernut.com/forum/showt...759#post289759

  2. #2
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  3. #3
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    pundit in 12/2005, no more working pic in old post:

    Fixed my 'Sword' fan speed controller
    Well after several weeks of having nothing but maximum blower speed available I decided it was time to investigate one of the common quirks of the E34/E32 series... the 'Sword' module. As the fans variable speed control would work very occasionally (even if only for a few seconds) I realised that it wasn't a case of blown Mosfet transistors but most likely a suspect solder joint, probably where the connector socket joins the PCB. Well a crook joint it turned out to be, but not the connector. It was a capacitor as marked.

    It took a while to trace. I removed the sword module from the climate control box, but left it plugged in. By setting the fan controller about midway and flexing the PCB I could cause the fan to cut in and out. After re-soldering the connector joints I retested it but no joy. Still the same. Finally I pushed a prodded each component on the PCB until I narrowed it down to the said capacitor. The slightest touch to this triggered the intermittant operation. I resoldered the capacitor and VOILA! Sword fixed!!

    05-04-2005:
    The other possibilty is cracked solder joint where the connector socket is attached to the PCB. This can cause intermittent operation. Try removing the sword, then plug it in and the switch on the fan and gently flex the sword PCB as well as pressing on the various components (including the connector) that are soldered to the PCB. See if you can cause the intermittent operation you have been experiencing by doing this. It then should be possible to isolate the cause.
    ----------
    The thing you refer to is called a relay. (bottom right of picture)
    It is an electromechanical switch. It may have dirty contacts (these are located where the spark occurs) or some other part of the circuit maybe causing the fault. If you can see the relay operate but sometimes the fan doesn't start then I would suspect dirty relay contacts. However if the relay switch contacts are fine and the voltage supply and earthing is okay then simply manually forcing the relay to close will make the fan operate anyway even if the circuit that controls the relay is faulty.

    Of course it could also be the fan motor itself, tight or seized bearings etc.
    __________________

  4. #4
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    More pics "failure mode to the sword, no fan - DIY repair" http://www.bimmerboard.com/forums/posts/1249909
    John sent me an email with the pics: Hi Erich, I wanted to update you on the inoperative blower situation. I’ve found yet another failure mode on the sword, cracked solder joint on the connection between pin #5 and the circuit board. I’ve added pictures.
    Wave soldering is great for some things, like surface mounted components, but given all the places that we've identified poor or broken connections in the various components of our cars I have become very sceptical of its use. Pioneer had similar issues with the power supplies of their Elite HD projection TVs from about this same time period, and the fix was to re-solder by hand every connection on the circuit board... Pioneer's solution was to only re-solder the connections broken at time of the repairs. This practice ensured that the board would fail again. The common thread I see is high current draw, possibly too light conductor, and resultant higher than needed temperatures on the connections. The heating up & cooling down cycle is just like water freezing in the crack of a rock, eventually the solder fatigues, crystallizes, cracks & breaks. Unfortunately, given the age of our cars, and the number of cycles they've endured, I suspect we will be seeing more of these issues in the future.Re-soldering adds material which strengthens the joint as well as providing additional mass, larger contact area, and taking longer to heat up & cool down, helping to reduce the stress on the joint. Thanks again, John

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