Surface Mount Components

[Gwyn Reedy]

Scott,

Size and color do not necessarily identify the component value. There are a
number of standard size packages and within each size there are a range of
values available. As to color, I have not seen these components identified
by color, but that isn't to say it isn't done. All the ones I've seen have
some markings stamped on them - letters and or numbers. Might be able to
make some sense of those if you could see them.

I wonder if the toasty components are capacitors or not. Not sure why the
failure of the electrolytics would cause the smaller caps to burn - unless
the big caps were limiting voltage spikes and the working voltage of the
small caps was substantially exceeded. Could be that the small items are
Zener diodes and they would also toast if presented with too high a voltage.

Not much help...  Any chance to find a good unit to be inspected for the
markings on the dead components?

Gwyn Reedy
Brandon, Florida
mailto:mgr at mgrcorp.com

-----Original Message-----
From: owner-diy_efi at diy-efi.org [mailto:owner-diy_efi at diy-efi.org]On
Behalf Of J. Creech
Sent: Sunday, September 24, 2000 11:23 PM
To: diy_efi at diy-efi.org
Subject: Surface Mount Components


OK, kinda got a little problem. I have an EPROM ECU out of a '91 Mitsu
Eclipse GSX, 2.0L Turbo AWD. The power filter capacitors went bad, started
leaking electrolyte all over the pcb. The stuff has eaten through the
conformal coating, and under two of the caps has eaten through the traces.
 I think I can patch the traces, but here is where I run into my problem.
There are 2 seperate surface-mount capacitors that are a little on the
toasty side, I believe from being mounted across the same bus as the worst
of the electrolytic caps. I want to replace these when I perform the repair.
The hitch is this: they're unmarked.
 I have little to no experience with surface-mounts. I try to stay away from
them as my hand is so shaky I nearly can't work on the standard stuff. But,
in this case I'm making an exception.
 My question is, how are these things identified? Both of them are the same
color (kinda medium brown) and the same size. There are also others on the
board that look identical to them, as well as others that are different
colors, sizes, etc. Can I safely assume that all the ones of the same
size/color are the same value (within a certain tolerance)? Can I use other
S.M. components (off of other techno-debris I have laying around) that are
same size/color?
 I hate to bug you guys, but I'm not finding answers in the places I'm
looking. (Hmmmn. might be the wrong places, ya think?)
 Any insight would be appreciated.

Thanks in advance
Scott Creech

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