Vintage Synth Repair

Hi all,
I have a Prophet 5 rev 2 in for service. Originally the problem was  
that autotune didn´t work.
Now autotune, program saving and retrieving as well as all voices  
works great.
However, I am unable to get the keyboard to scale correctly. The top 3  
octaves is correct, but the bottom two octaves are slightly off  
scaling, enough to sound out of tune. I am able to trim the DAC  
according to spec, and it helped, but not enough. I tried turning the  
trimmer even further (lower than +5.000), and even though it helped,  
it is not enough, and I reach the end of the trimmer. I checked the  
power and it is slightly off (+15.3V and -14.75V). I could start total  
recalibration of the whole synth, but that is a staggering 80+  
trimmers (which are sealed now), and it seems a bit overkill when all  
I need is adjustment of keyboard scaling.
Any hints appreciated.


Terje Winther
terje.winther@...
http://www.wintherstormer.no/