[sdiy] LM326 anyone? DS-2 TURBO-NIGHTMARE!!

[Bob Weigel]

Oops.. being late at night I wasn't thinking what the third pot would 
be. hehe.  As soon as I went to bed I'm like "Duhhh..pitch bender?"   
The way it was drawn I thought they had some hidden pot in a hole 
somewhere for external tuning. hehe.  Bender was dirty, dco's tune now.  ..

HOWEVER..I forgot to add another odd problem.  The third dco for the 
divide down poly synth... you have to touch it with a probe to get it to 
start up!  Glancing a probe over pin 1 and 2 of the 74LS221 usually will 
do it.  I had replaced that chip.  Quite strange.... before it would not 
tune but was oscillating. Now... it tunes but...isn't oscillating until 
you have the probe on 1M and glance it across those points!

Meanwhile LM326 advice appreciated.  I could just convert the supply to 
78xx series.. -Bob

Bob Weigel wrote:

> I should have known by the front panel that we might be in for 
> trouble.  Hehe.  I had to totally rebuild the lfo board in 
> particular..clean up mildew on the back inside.  Lots of dirty sockets 
> on other boards and blown chips all over the place.  Got it MOSTLY 
> working then.  stupidly forgot to unground my probe and the ground 
> flipped off and skated and arc and we apparently have a dead LM326.
>
> ALSO though if anyone is familiar with the unit..where the heck is the 
> 2nd tuning pot?  It shows the front panel pot on the diagram, the 
> trimmer on the oscillator board (1 for each DCO)..AND ANOTHER which 
> goes off pin 5 and 6 counting from left I see... please..if anyone 
> knows don't make me trace it. I've poured so many hours into this 
> thing....it's been on the bench working late 4 nights on it now...  It 
> blew up a BUNCH more chips when the regulator went down.  Horror 
> story.  But you can't let these things die they're just too cool! :-)
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