Vintage Synth Repair

It is good to know when somebody figures out the solution to their problems and it sounds like you had to do a lot of digging to solve that particular problem. Good work. Maybe someone customized it to be more polite and less aggressive.
  PT

From: Jim Blair <ceratos@...>
To: vintagesynthrepair@yahoogroups.com 
Sent: Friday, February 22, 2013 7:42 PM
Subject: Re: [vintagesynthrepair] Still more Moog Source weirdness.

  
Found the "source" of the volume issue on osc 2.

At some point in it's life, the CA3080 op amp at U24 was faulty (I assume). It was replaced by an RCA 314, which I can't seem to find any reference to online.  

I had a spare CA3080, and swapped it in.

It immediately fixed the osc2 volume problem. Now I can overdrive the filters again!

I'm not sure if this info is helping anyone, but what the heck, I like it when people post solutions.


Jim





At 10:00 AM 2/22/2013, you wrote:

  
>
> While looking for my Source owner's manual the other day I came across a printout with the  parameter list and values. I'll check it tonight but it seems unlikely that osc2 is supposed to be that much quieter.
>  PT
>
>From: Jim Blair <ceratos@...>
>To: vintagesynthrepair@yahoogroups.com 
>Sent: Friday, February 22, 2013 12:25 AM
>Subject: [vintagesynthrepair] Still more Moog Source weirdness.
>  
>So pitch calibration went great. However.....
>
>When setting the volume of osc2, the data wheel will increase the 
>volume until the numeric display reaches 58, then the volume starts 
>dropping again as the display approaches 99.
>
>But even at it's volume peak of 58, osc 2 never reaches the volume 
>of osc1 at 99. So I'm assuming the the osc 2 volume is reaching 
>approximately half volume, then instead of continuing up to full at 
>99, it just decreases back down to a quieter volume again. (In other 
>words, 58 is not the equivalent of a normal full volume.)
>
>Very odd.
>
>Jim
>
>