Vintage Synth Repair

hi list,

i just got an MS20 (i think its mk2 version with the screw on the vca section.).

it has some problems in its patchbay:

the S/H does not work (the output does not output any stepped voltages, so i cannot know if its the sampling or the clocking section that does not work), 
the linear VCA also does not work, 
the White and Pink noise output does not work (and the noise waveform in vco1 does not work either) 
and the pitchbend output does not work.

any suggestion on what to look for?

are these repairable? 
or do these sections contain any custom unobtainable korg chip?

of course, i will give it to my tech to repair it, but any general help and guidelines are very helpful.

all other patchpoints and functions work fine.

any help?

many thanks in advance,
best regards,   :-)
Bakis.


Bakis Sirros - Parallel Worlds / Interconnected / Memory Geist
[Doepfer_a100] group owner
www. parallel - worlds - music. com
www. myspace. com/ parallelworldsmusic
www. myspace. com/ interconnectedmusic
www. myspace. com/ memorygeist
www. DiN. org. uk
www. musicamaximamagnetica. com
www. shimarecords. co. uk
www. rubberrecords. gr
Athens - Greece