[sdiy] sem repair

[Magnus Danielson]

From: mark verbos <a0284520 at addcom.de>
Subject: [sdiy] sem repair
Date: Fri, 19 Jul 2002 23:42:22 +0200

> Hi,

Hi Mark,

> I am fixing an Oberheim SEM and need some guidance. The owner tried to 
> trim the V/Oct response and sharted something that caused the power 
> supply to blow up. I have replaced the 723 and got the power working 
> again, with the VCO's cut off from the power. However, when they are 
> connected, the positive rail drops from 15 volts down to 8 volts. I 
> can't check what's wrong with the VCO's if the power isn't working? What 
> could cause this? I have never seen a dead OP amp mess with the power 
> rail. could it? Anyone know this problem?
> 
> please help!

If I recall correctly is the 723 wired up to duck if too much current is drawn,
but I am not sure that the negative side ducks if you load that side too much.
Anyway, if the 723 blew up we are talking the positive side at least.

Check where there's excess heat...

Cheers,
Magnus