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Re: Cassette replaced Posted by Ari [Email]  (#2847) [Profile/Gallery]
(more from Ari) on Tue, 22 Jun 2004 05:55:29
In Reply to: Cassette replaced, MarkusJ, Mon, 21 Jun 2004 22:23:15 Members do not see ads below this line. - Help Keep This Site Online - Signup |
I don't know all of the failure modes of the DI (heck, I know very few of them), but the one that comes most to mind would be low cycle fatigue - cracking due to the periodic expansion and contraction of the the epoxy / circuit board as the DI heats up and cools down with engine start/stops. That fatigue cracks board traces, destroys solder connections, and rips out swaged connections inside components. The location of the DI is about the worst possible place for electronics in the car - mounted directly on top of a big heat source, and heat kills electronics. I work on jet-engine mounted control systems, and we use fuel-cooling to keep the electronics from burning up. The DI doesn't have any cooling except radiation, and you'd be surprised how hot underhood temperatures can get, even compared to the outside of a jet engine.
So I expect the epoxy cracked because the thermal stress finally got to it. Epoxy is brittle. That said, you could always grind out the epoxy and see if you've got a blown cap. If that fixes it, the resulting DI would be useful as a temporary spare, the 'limp home' unit in the trunk. I wouldn't assume that if you found one fault, that the DI was 'all better.' If one component has failed over time, vibration, and thermal fatigue, all the rest of the components have seen those conditions, too. I'd assume that the DI was just a close association of parts all waiting to quit. So it makes for a good 'second chance' unit to keep you from being stranded on the road, but I wouldn't use it as my primary.
posted by 192.249....
, Mon, 21 Jun 2004 06:05:11, Tue, 22 Jun 2004 05:55:29 <-- Viewing This Message
, Sun, 20 Jun 2004 08:01:01
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