EEVblog Electronics Community Forum
Products => Test Equipment => Topic started by: TerraHertz on June 14, 2017, 08:36:57 am
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A friend's car engine management computer failed, and was replaced. I asked for the old one, to tear apart.
So here it is, for anyone interested. This was for a 2001 Astra.
Firstly it was surprisingly small.
Secondly, hermetically sealed, with no potential for opening non-destructively. It took a vice, cold chisel and hammer to open up. It's like a hard disk construction - diecast case and stainless steel lid, but with the lid rim glued into a slot with a tough rigid epoxy.
What really surprised me is the inside. If I'd known what to expect I'd have used a different method of opening it, that didn't produce so many fragments of the epoxy seal.
The 'boards' are ceramic wafers, with naked chips wire bonded to pads. All visible because the whole thing is encapsulated with that clear but soft and tacky silicone material. Result: every speck of broken epoxy and metal I created while removing the lid, stuck to the silicone. The worst of them removed with tweezers for the pics. I would NOT want to fall into a pit of this stuff.
Very definitely "No user serviceable parts inside."
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I've seen BMW "brains" similar to that.
I'm surprised they don't require the old part as a core, like here in US.
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Is that tantalum cap blown or is it epoxy fragment on it?
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something even smaller: for fiat engines, about same age (and newer).. the whole thing is the size of two fingers. I don't have any laying around at the moment or i'd take a photo. i seriously tought my boss was pulling my leg, as i'm used to way bigger ECUs
same wire-bond type of construction
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Now you've done it and HAVE TO put up high res pics.
Looks cool @ 500% but blurry. :(
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I feel hungry. Please take some more close up photos. If you can.
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You can get these open without smashing them, its a bit time consuming but can be done.
This model is prone to failure, 99% of the time it's one or more of the link wires with broken aluminium solder joint
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you can open many of those by heating them up to soften the sealant.
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I'm surprised they don't require the old part as a core, like here in US.
A core charge would imply that the defective part is rebuildable. That thing really doesn't like like it could be repaired in any kind of economical manner...
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I'm surprised they don't require the old part as a core, like here in US.
A core charge would imply that the defective part is rebuildable. That thing really doesn't like like it could be repaired in any kind of economical manner...
There are many shops here that do nothing but ECU rebuilds. Also, if you buy it from the dealer, they almost always require the old one or charge a core fee.
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I know that they are usually taken back for rebuild. I replaced one on my vehicle a few years back, and had to return the old one for a substantial core deposit. But that one actually was rebuildable, with standard fiberglass PCBs, conformal coating rather than that silicone gunk, and a case that could be opened without having to smash it. Being an electronics guy, I couldn't help but open the thing up and look for bad solder joints or obviously burnt parts before just swapping the whole thing out.
The rebuilder also needed the vehicle VIN number and odometer reading to flash them into the new unit. Apparently, the unit needs to "handshake" with the other modules in the vehicle, and this info needs to match or the vehicle won't start.
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There's a lot of craptographic handshakes on these kind of devices, yes. I'm glad that the ones I've worked with (various Bosch EDC17, GM E98 and AISIN TCMs these days...) are just standard PCBs. Still a pain to open.
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Is that tantalum cap blown or is it epoxy fragment on it?
Neither. A couple of the yellow tantalums have what appears to be hand-written felt-tip pen marks, under the silicone sealant.
Here's a 2MB image. An original camera image is 5MB, this is cropped and slightly more compression. Appears identical to the eye.
http://everist.org/pics/misc/20170615_7362_95.jpg (http://everist.org/pics/misc/20170615_7362_95.jpg)
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Mailbag for microscope fun?
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Mailbag for microscope fun?
That took me a few moments to figure out what you meant.
But I have a good microscope. Does anyone want even higher resolution shots?
Bear in mind we'd be looking through the clear gel, which doesn't have a flat surface. So high magnification images wouldn't be optimal.
I'm going to be pretty busy this coming week. So, probably won't do this till sometime after the 26th.
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Grounding scheme looks interesting (on all 4 corner with 3-4 links and silicon goo).
Is the board inserted into black connector and can be moved? If so, some diagnostic and repairs can be done by removing ground links. removing silicon (not sure how), unglueing the board (very likely that it is glued) and opening connector. Repair can be just possible for very desperate client by qualified repairmen.