CHROMA POLARIS TROUBLES, CEM 3374.

[AntonEriiksson]

Been a few years I know... but just in case anybody is still around or monitoring.
I just replaced the membrane panels on my Chroma Polaris as well as moved the battery backup to an external metal box at the rear where the serial plate was. Everything lit up. I had to reprogram a patch to test and it works and passes various diagnosis tests. But... I've got that drifting but consistent out of tune problem that's present up and down the keyboard but mostly in the higher octaves. It can't be corrected with any of the tuning functions and I've checked the pitch bend and the detune parameters. I'm pretty sure it's the capacitors from reading this conversation but of course I can't be sure - I'm not an electronics tech, but I'm decent with a soldering iron. I'm hoping someone can describe the exact capacitor I need and possibly a source. I'm including a grab from the schematics as I'd like to be sure that these are the caps discussed above/previously. Thanks so much to anyone who can lend a hand.
I'm including the link as well as attaching the image file. Polaris pitch capacitors
chromapolaris_pitch_caps.jpg

Hi Gary,

I have the same problem. I did all steps of calibrations from the service manual, still have voice 1 out of tune. I ordered new capacitors yesterday (both for the voice 1 and the power supply), should have them here tomorrow. I will replace them as soon as I receive them, and see if the problem disappear. I swapped the IC's of voice 1 from another voice that I know is working without any tuning problem. It didn't help, so I hope the problem is bad capacitors as mentioned earlier in this thread.

[Cellomangler]

Anton - So is it those two capacitors that I circled on the schematic that you are replacing?
Would you mind sending me the link to where you are purchasing the caps?
Is the power supply repair just a precaution or do you attribute any tuning problems to it...?
Thanks for chiming in !

Aside... I'm going to sample a bunch of voices before I do the cap work. I'm having to program from scratch but that's the fun of the Chroma Polaris. I can tune the samples before using them in a Nord Wave and in software. I'm just afraid there's a chance my Polaris might not come out of surgery intact.

[njosnari]

I'm currently restoring a Polaris from the ground up. I received it with no voices working, all oscillator and filter chips removed. I've got it up and running again, but voice 1 and 6 are giving me massive detune problems. I've swapped the CEMs around between the working and non-working voices, as well as the other ICs. I've also went ahead and replaced c700-c704, c701-c705, and all of the decoupling capacitors c702,6,8,10 and c703,7,9,35 and still have the problem. I'm all out of ideas at this point. Is there something I could be overlooking?

[Cellomangler]

njosnari - did you check the pitch capacitors for A and B as indicated in my attachment above?
I haven't done the job yet so I don't know if it will fix my problem and I was hoping someone would chime in and tell me exactly what parts to order and from where...

[njosnari]

Yes, I've replaced those caps, and it did not fix my problem. I suggest you go for it! I would also recommend following the calibration procedure outlined in the service manual with special attention to the DAC voltage calibration.