Cgs synth

>When I hooked it up, it worked nominally for a couple of secs and then the

tantalum cap blew up in firy fury. Green flashlight all over my flat.
Spectacular :)

1) Maybe you put the Tant in backwards.
2) Maybe you did not have one with a high enough rated voltage.
3) Tants do that for no apparent reason from time to time. I refuse to use
the nasty things myself. Use regular Electros with a minimum rated voltage
of 25V.

>NOTE3: I have powered it up on 15V and 18V but this should be ok. All

components should handle the extra volts.

Do NOT power CMOS on 18V - that is beyond their maximum rating and usually
results in the chips going the same way as the Tant. Yes, I mean explosive
releasing of smoke.

>Both times something fatal happened. The 15V fried the filtering resistor,

and the 18V just went along and blew the tantalum to kingdom come. Clearly,
there is still a short.

Sounds that way - or you have your power connected backwards to the whole
module. Or the Tant was backwards and was acting as a short at the lower
voltage, and blew at the higher one.

>NOTE5: All the logic chips work, not shure about the lm358, but can't see

how that should matter in blowing resistors and caps!

I'd replace that with a TL072, but only to make things work better.

If the chips are socketed, remove them from the sockets before you go short
hunting again.

Ken
_______________________________________________________________________
Ken Stone sasami@... otherunicorn@...
Modular Synth PCBs for sale <http://www.cgs.synth.net/>
Australian Miniature Horses & Ponies <http://www.blaze.net.au/~sasami/>