[sdiy] sem repair

[epeasant at telusplanet.net]

Well, when a short is accidently applied to a circuit, it 
is excess current flow that causes the damage. It is 
virtually impossible to draw enough current through a 
capacitor in this transient manner to cause damage. 
Semiconductors and resistors are a different story, as they 
can conduct large sustained dc currents. But resistors can 
be seen (and smelled) when they are overloaded, so that 
leaves semiconductors as the primary suspect. If the fault 
occurred spontaneously without apparent cause, I would 
certainly check capacitors (especially tantalum) early in 
the troubleshooting process.

Take care,
Doug

______________________
The Electronic Peasant

www.electronicpeasant.com

> yes, definitely caps of some variety..
> 
> I have seen things screw up a synth that defied logic..
> But, 9/10,
> there is a cap out there dragging down a rail somewhere.
> ;)
> 
> Rob
> 
> ----- Original Message -----
> From: "Gene Stopp" <gene at ixiacom.com>
> To: "synth DIY" <synth-diy at dropmix.xs4all.nl>
> Sent: Friday, July 19, 2002 5:50 PM
> Subject: RE: [sdiy] sem repair
> 
> 
> > Tantalum caps?
> >
> > Best Regards,
> >
> > - Gene
> >
> >
> > -----Original Message-----
> > From: mark verbos [mailto:a0284520 at addcom.de]
> > Sent: Friday, July 19, 2002 2:42 PM
> > To: synth DIY
> > Subject: [sdiy] sem repair
> >
> >
> > Hi,
> >
> > 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!
> >
> > mark
> 
>