[sdiy] sem repair

[cyborgzero at comcast.net]

----- Original Message -----
From: "harry" <harrybissell at prodigy.net>
To: <epeasant at telusplanet.net>
Cc: <cyborgzero at comcast.net>; "synth DIY"
<synth-diy at dropmix.xs4all.nl>
Sent: Friday, July 19, 2002 11:26 PM
Subject: Re: [sdiy] sem repair


> Mostly agreed...
>
> sometimes it is VOLTAGE that kills... not current (especially in the
> case of FET or CMOS components).
>
> Also... if the short circuit causes a reverse bias on a tantalum
cap...
> it can be damaged in pretty short order (teehee)  and fail shorted.
>
> that said... I agree with Doug... semiconductors are the first
suspects
>
> (you guys just have this terrible phobia about caps, dont'cha?  I
mean
> they
> are almost never the culprits... YOU just hate them because #1: You
> checked the
> semiconductors first, and didn't find any bad... and #2: A bad cap
is
> the last thing you look for and can be very hard to find !!!)

Yep, exactly my problem.. ;) But, OTOH, if someone *has* gone poking
around in there prior to yourself and *left* it broke ( I have yet
ANOTHER synth from a wanna-be tech in here.. Sheesh, its impossible to
find out what they have done!) then semiconductors are suspect..

A recent entry into the hall of fame/shame was a unit that was
*allegedly* serviced by a rather reputable shop in the Midwest and
they were told *unfixable* come pick it up and pay the eval fee.

Well, a reversed diode here and an opamp soldered in wrong (bridge)
had me literally out of my head and thinking I would *never* take
another repair in again..

Then, after all that, it *still* didn't work...

Damn cap. :(

Rob