OldSynths

Hi Bob,

The chip was a 7493 or 7454, I forget which at the moment.  

In any case, I've rechecked all the soldering on the new chips, and replaced the chips I 
mentioned, all to no avail.  When I say that I "traced voltages" I mean that I followed 
the CV from its source through each successive section of the circuit, making sure 
that the inputs and outputs on the various chips were what they're supposed to be. 

One question:  What should I expect the voltage DIRECTLY out of the oscillator itself 
to be?  I assume it should change proportionally with the keys played, and drop 
dramatically when a played key is released, correct?  What would a completely dead 
oscillator voltage look like?  No voltage at all?  Power rail voltage?  Something else?

Also, on rechecking my power supply voltages, I find that I'm getting +15, +5 and
 -19v, instead of the +15  +5 and -15 I got after re-capping it the other day.

Do voltages from the power supply normally fluctuate this much?  If not, could this 
high negative voltages explain a dead synth?  Having re-capped the power supply, 
does this -19 volts suggest a different component needs replacing?

Thanks for the continuing help!

David


--- In oldsynths@yahoogroups.com, "Bob Weigel" <sounddoctorin@m...> wrote:
> Hmm.  Well if you have my 'luck'..then yes another chip working for many
> years with no problem decided to play out at that very moment :-)  What kind
> of chip is it?  I didn't understand what you meant by 'traced voltages to'
> or whatever.  If it's a octave divider, do you mean a top octave
> synthesizer?  Or just a divide by two for 'sub' type function?  Arp pro
> soloist...would think you mean the latter. -Bob
> 
> ---