scratch that-mods, you can delete. swapping U12 on the common analog board for a new 741 solved the issue.

Hi folks, I'm wondering if anyone has any ideas on an issue I have. Working on a non-plus MM. The problem: activating the "osc _ freq" button in the modulation section creates a pitch offset on the respective VCO. so, for example, if the machine is tuned to exactly zero, and all the VCO's are tuning...

WERECOW!!! you nailed it. wow. hats off, my friend. the ground wiring on the 5 underside boards is wired in series, not parallel. there was a ground break that i couldn't see visually, which caused the ground to go "silent" all the way downstream. fixed it! poly AT is responding! if i can calibrate ...

werecow-aha! thanks for the reply, sorry for my late response. i hadn't even thought to check the ground continuity on those boards, as i was so focused on the 8.5v rail, assuming it was "bleeding" somewhere. i'm not measuring against chassis ground, i'm measuring against the "internal", or circuit ...

stab-thanks. all caps have been replaced; i don't think it can be local to the lower 5 boards, as best i can tell.

Hi all, so I am in my LAST phase of a CS80 resto, and I have a problem that is truly stumping me.... there are a bunch of ground bus lines to the poly AT boards. These should all read 0v, obviously, but they all read +8.5v. there are a bunch of them, on multiple boards, so it's very very labor inten...

nicely done! quick question: i have a pro-soloist, and some of the presets don't work(about 1/3?). it's never been a huge issue, the synth is still playable, but on this subject, i might as well ask: in your digging into the schematics, did you find anything that might be a likely culprit for this i...

Great-thanks Rhino. That is roughly what i would expect to see; I'll sniff around further at the actual keyboard pcb, and see what i can get readings on.

yup, all 5 lower boards have been fully rebuilt, as has the PSU, and a number of the upper boards. yea, as rhino said, it's an individual sensor for each key. at the keyboard pcb, there is no play in voltage, only a slight play in impedance, on pin #3. this is, as best i can tell, normal. basically,...

So I am trying to get the AT on a CS80 working. It is currently pegged at maximum value, in terms of it's functioning via the control panel. I have the schems, but my issue is that I don't understand what voltage I SHOULD be seeing into/out of the TSB/TRG boards. I get no play in voltage on the inpu...

hey folks-has anyone out there over done this? the service manual is not translating well to the actualization of the procedure. i really just need to figure out how to scale the keyboard; the terminology is not clear for me in the calibration section. thanks.

i've got the schems/service manual, but the procedure has some errors/omissions, and even then, doesn't provide a comprehensive means to scale the audio VCO, at least not under the "tuning" header. anyone ever make their way thru the procedure? thanks.

I agree-I've listened to multiple TTSH demos now, and I can say with confidence that NONE of them sound even remotely like a 2600. I'm not throwing shade at the project, its a great idea. I just have no idea why or how it doesnt sound even close, considering the schems are supposedly duplicates. I b...

ha-yea, i got it in tune and then just put it in studio to play. there's a few slight voice discrepancies, but they only appear and go on certain patches.

and yes, i took the shots the RIGHT way up-in preview it looks fine. i blame tinypic.

more photos.