Vintage Synth Repair

Has anyone experienced issues with fluctuating voltage on the CV Outputs?  

It's the CPU board (confirmed by swapping/testing another board). It doesn't output consistent CV voltages on any of the channels (1-4). They fluctuate, and a quick test is tuning with the MC-4, holding SHIFT and pressing #9 (Tune) to tune a VCO to A 440 Hz. The Total Tune calibration pot doesn't help either, it should operate perfectly in the center position but does not. 

Any suggestions on what areas of the CPU board I should focus on?

Thanks Scott.  I'll take a look.  I can confirm it's not the power supply lines.  There is an onboard oscillator (Toyocom 8.0000) but I don't think it's the issue as it's purpose is not used in the CV outputs upon examining the service manual.  I could be wrong though.

monads

--- In vintagesynthrepair@yahoogroups.com, scott frye <painintheamp@...> wrote:

>
> Check ALL power supply lines to see if they are stable FIRST.
> 
> Check oscillator stability anywhere there IS one.
> 
> Either one of those may give you a clue
> 
> -- 
> Scott Frye
> 
> Audio-fixation.net
> 
> Vermont
>