[sdiy] sem repair

[René Schmitz]

At 23:23 20.07.02 +0200, Magnus Danielson wrote:
>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.

IIRC the SEM has a tracking powersupply, so when the pos side is ducking the 
neg side should too.

Cheers,
 René




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