Help with Polysix repair

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beatnik
Learning to Wiggle
Posts: 11
Joined: Tue Jan 14, 2014 3:21 pm
Location: United Kingdom

Help with Polysix repair

Post by beatnik » Tue May 19, 2020 7:01 pm

Hi everyone

I am literally going insane on a Polysix repair. Thought I'd post here hoping to get advice by someone more experienced.

The synth has been fitted with a new KLM-367 repro board. I have salvaged the original 8045 MCU and a couple of other bits. The remaining are all brand new components.

I am having the exact same problems before the board change. Basically the filter cutoff, filter envelope amount, keyboard tracking and pw/pwm controls operate with a very slow response. As the pot is turned, the corresponding parameter slowly sweeps to the desired value.

Probing the outputs on the 4051 IC18 / IC19 while turning the knobs confirms that on the corresponding signals the voltage changes much slowly compared to the controls that are properly working.

I have tried disconnecting the other boards and just leaving the KLM-367 alone with the front panel boards and the same behaviour persists.
I have replaced the 4051 and the buffer opamps just out of desperation but obviously no luck.

I am pretty sure the problem must be on the KLM-367 and I am starting to really suspect perhaps the 8045 MCU might have been corrupted ? I don't know if that would be even possible, I am making a guess just because the other parts are new.

I have completely ran out of ideas and it would be great if someone can give any suggestions.

Thanks in advance

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chiasticon
Wiggling with Experience
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Joined: Thu Mar 19, 2009 5:33 pm
Location: the heart of it all

Re: Help with Polysix repair

Post by chiasticon » Wed May 20, 2020 6:29 am

I don't have any direct help to offer but it occurred to me that this might be useful: https://www.theanaloglab.com/interactive-repair-program

basically they help you fix your synth remotely. I've never done it but sounds like you have the right tools and skills and just need help finding the exact fault.

good luck!

beatnik
Learning to Wiggle
Posts: 11
Joined: Tue Jan 14, 2014 3:21 pm
Location: United Kingdom

Re: Help with Polysix repair

Post by beatnik » Wed May 20, 2020 6:45 am

Thank you, that's actually a very useful service. But I think I will try harder first. I would love to save the money !!

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werock
Ultra Wiggler
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Location: London

Re: Help with Polysix repair

Post by werock » Wed May 20, 2020 7:39 am

You might get more help in the DIY section of the forum rather than here.

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seal_cobblr
Learning to Wiggle
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Joined: Wed Feb 01, 2017 1:37 pm
Location: Copenhagen, Denmark

Re: Help with Polysix repair

Post by seal_cobblr » Tue Jun 09, 2020 4:20 pm

Bummer man. Perhaps the seller of the replacement board could comment on their experinces when problems as yours remain after replacing the board.

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