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Discussion about the Korg PolySix synthesizer

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Re: [PolySix] Effects Knob changing Waveform

2018-03-03 by <backshall1@bellsouth.net>

I don’t think it’s likely that the diodes in backwards would damage anything, just prevent them from working. The P12, P13 lines would affect how both switches are read, but if there was a problem with them it would affect a lot of other things. Maybe IC 28 is putting the wrong signal out on pin 1? It looks like it should be high for saw and low for pulse or pwm. The waveform switch also has a couple of diodes but you didn’t mention changing anything on that board.
Don B.
 
Sent: Saturday, March 3, 2018 1:36 PM
Subject: [PolySix] Effects Knob changing Waveform
 
 

I'm in the process of refurbishing a polysix. There was pretty bad corrosion. All the boards were taken out, cleaned, and parts were replaced if needed. I also populated a clone klm-367 pcb from Jed Jorgensen and a clone klm-370 I bought from an eBayer. All of the functions work except the Effects pot. Nothing happens in the off or ensemble modes but, when using the saw waveform for the oscillator, the chorus and phase change the waveform of the oscillator to pulse (and there is no chorus or phase effect).

When I built the klm-370 I mistakenly installed the three diodes wired to the effects pot in reverse. So I'm assuming I damaged whatever multiplexer or dac the Effects pot is wired to. I changed most of the ic's on the klm 367 board (and added sockets), is there any component in particular that both the oscillator waveform selector and effects pot both run through?

Every other function works so I don't think the CPU chip is bad, but I may be wrong. 

Thanks

 

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