Vintage Synth Explorer Forums

so i got my divider card all sorted out. 12 bad mm5823 chips. all done,whew. slowly moving down the line of problems...

next up to bat, bad voice cards. i dont actually know what theyre called, but the cards on the lower deck, down by the buffet, underneath the shuffle board and the pool. there's 61 of em, they fit into sockets.

i have a good handful of keys that dont trigger. i swapped around 2 of the 820K value cards, and verified that the actual cards are the problem, not key contacts.

but since i cant access them with a DVM while they are in their sockets, i cant figure out what part has gone bad. does anyone have a guess? its gotta be either the IC, or one of 3 film caps(which i rarely see go bad, but rational thought+soldering gun=disaster waiting to happen).


heath? any other PM owner's ran into this? thanks for the help... next up after this, the preset loudness problem, AKA no sound when i use the presets loudness value.....


EDIT: voice card issue solved, found a way to measure.

Actually thats what I would try first. The IC and then the caps.

thank heath. im feeling pretty lucky, sourced the dm7670 chips for $6/piece, only needed 3.

with my $4/mm5823's(bought an entire set of 24, since they are known to be crappy), $18 for dm7670's, and $70/new bushings, this $400 polymoog should be in tip-top shape this week!

last problem would be that certain LED's dont light up, but all front functions are working, so that would really be a vanity/resale concern.

next up, the most daunting exterior overhaul of a synth i've ever done...cs40m...pics/thread to come.