Xpantastic!

Hi all, and thanks for all the help regarding fixing the M12.
I am slowly progressing:
- Now all voices, both 1-6 and 7-12 works (apart from one voice), but  
it still doesn´t tune properly. Massive sounds from 11 VCOs though  :-)
- I found a strange repeating ripple of approx. 100 - 150 mV from the  
power supply. It looks (on the scope) like two ripples rather close,  
then an interval, and then the two ripples repeat again, all  
microseconds apart. I´ve read in the archives that this could be  
enough to throw off the auto-tune process, so I better recap the power  
supply, right? There usual hum from the transformer is a bit loud, but  
I have heard many synths with loud transformers, so I am not going to  
do anything about that.
- All keys work again, although some needs to be cleaned properly  
(they are intermittent)
- All encoders work, but one is way too slow, so I probably need a  
complete new set of chips for that one
- Still a few buttons that don´t work properly (I have to push  
repeatedly and/or hard to get it working), but I now know there is  
nothing electronically wrong, just a tired switch underneath.

- The voice still missing puzzles me: I thought I traced the error to  
a broken CEM3372 (the filter part works, but the VCA part seems to be  
broken). So voice 6 is dead, but if I swap the CEM3372 between, say,  
voice 5 and 6, then voice 5 becomes dead and voice 6 starts working.  
So I got a fistful of CEM3372s (12 actually) from  
Technologytransplant, but they don´t work, or the M12 doesn´t like the  
fact that the "new" CEM is from another date stamp. Any ideas?

- I also started cleaning the synth - following the tip to clean up  
the inside of the display window as well


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