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DME Repaired w/pics

Old 07-31-2006, 03:40 PM
  #31  
skene
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Be a bit careful with the silver stuff, since it's electrically conductive as well as thermally. As long as you don't get it on anything other then between the the heatsink and the transistor, it should be fine to use.
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Old 07-31-2006, 04:04 PM
  #32  
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I was afraid of that. -Since there's vibration to be considered in this application, I'd say DON'T use it, because that stuff might creep/migrate with heating/cooling cycles and bumpy roads.

Keith
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Old 07-31-2006, 04:18 PM
  #33  
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Thanks, glad I asked - I was about to do something very stupid!
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Old 07-31-2006, 04:52 PM
  #34  
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Old 07-31-2006, 05:10 PM
  #35  
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Actually, that looks like good stuff. I'm sure that its thermal transfer characteristics are very good; they seem to know what they're making.

A good and apparently unbiased comparison here: http://www.heatsink-guide.com/compound.htm

-Having said that, if these DMEs were assembled without any compound (which is quite possible, I mean they're not under massive thermal stress) then ANYTHING will improve reliability, and after 20 years I'd have expected whatever was on there to have dried up at least a little... and more likely quite a lot.

I did also find quite a number of hits when I searched for 'electrically conductive heatsink compound' some of which were forum posts by people who'd damaged stuff with incautious application of Arctic silver... for example, the first hit was: http://www.xtremesystems.org/forums/...ad.php?t=13742

Anyhow, in the TO3 heatsinking game, I only ever see the regular white heatsink compound used, and in this case I'd definately recommend against Arctic Silver anywhere near an insulated TO3, though I must confess, I'm tempted to get some for a couple of hot-running CPUs here at work!

Keith
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Old 08-17-2006, 02:16 AM
  #36  
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At the almost certain risk of jinxing myself, I declare victory!

It's been two weeks since I resoldered the leads on the transistor on the DME and the car has not died since then. The problem had been increasing in frequency and on the day I resoldered it had died 3-4 times, so (fingers crossed), problem solved :-)
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Old 08-07-2007, 02:03 PM
  #37  
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Still ok????

I just had this happen.

Oh, and that transistor is the injector driver, as I am told.

Would not running ballost resistors on bigger injectors increase the temps of the transistor???
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Old 08-07-2007, 02:45 PM
  #38  
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Originally Posted by toddk911
Still ok????
Yep, still ok. It's been just over a year now and I've not had it happen again. I probably have some higher res pics on my hard drive somewhere if that would help, let me know & I'll email them to you.
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Old 08-07-2007, 02:49 PM
  #39  
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Really don't think it's the injector driver. Pretty positive it is the coil driver, as when those solder's are bad, you won't get a flash from the timing light (meaning no spark)!

Did this a few months ago, been fine ever since.
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Old 08-07-2007, 02:49 PM
  #40  
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where is the dme relay located on late cars?
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Old 08-07-2007, 02:53 PM
  #41  
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Originally Posted by toddk911
Still ok????

I just had this happen.

Oh, and that transistor is the injector driver, as I am told.

Would not running ballost resistors on bigger injectors increase the temps of the transistor???
The transistor pictured at the beginning of the thread is the ignition driver.

Adding a ballast resistor reduces the current going through the transistor, reducing the temperature.
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Old 08-07-2007, 02:56 PM
  #42  
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Originally Posted by greenshoes3
where is the dme relay located on late cars?
DME relay is in the fuse box, DME itself is located under the front floorboard on the passenger side.
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Old 10-12-2010, 02:43 AM
  #43  
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So I am going to be honest, I never really fine anything relivent to myself here on rennlist in terms of repair.

However, I had this problem today and litterally got on here to just browse and came across this thread. Now, I would have fixed the problem by replacing the DME unit as a whole with one of my spares but I would have to drive the the shop and back tommorow. Since I found this post now I don't have too. I fixed the two broken solder points and all fixed no more engine shutoff.

Thanks alot
Ronald

P.S. Good Thread!
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Old 10-12-2010, 03:55 AM
  #44  
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My DME cant control IDLE, its not the electrovalve or the cables. Any clue what to look for?
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Old 11-23-2010, 11:58 PM
  #45  
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Greg, thank you for the thread! My 944 has been dead at work since last monday night, and tonight I was able to fix it thanks to your instructions.

Anyone want to buy a 944?
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