Discussion about the Korg PolySix synthesizer

Hi,

   I uploaded some scope photos for comparison when you get things
set up to look at your waveforms.

   Let me know if there are other signals I should capture.

     Bob



________________________________
 From: "dtonthept@yahoo.com [PolySix]" <PolySix@yahoogroups.com>
To: PolySix@yahoogroups.com 
Sent: Thursday, June 5, 2014 11:00 PM
Subject: [PolySix] Re: Dead voice and too fast EG
 


  
Hi Bob,

Okay so we've had a bit of a poke around... Thanks a million for the pointers, VERY useful.

The dead voice does indeed stem from a lack of voltage from the appropriate pin on a 4175 so we'll need to replace that. I had a look on Syntaur and they don't have 4175s, indeed an ebay search turned up nothing as well, however they do have a 4174 flip flop - are these interchangeable?

IC, MC14174B Flip-Flop
 
       IC, MC14174B Flip-Flop  
IC, MC14174B flip-flop.  
View on www.syntaur.com     Preview by Yahoo    

Otherwise would you have any suggestions for a replacement?

Secondly, we were trying to get voltages for IC10 and IC11. These voltages didn't change when I adjusted the controls, but they did move as the envelope cycled.

What's interesting is that when we were probing pin1 of IC11, suddenly the envelopes (which were set to maximum ADR) began playing exactly as you'd expect! It was a sudden miracle, which, unfortunately, only lasted for maybe 20 or so seconds before the behaviour reverted back to its normal problematic self.

We spent a bit of time prodding the board to see if we could recreate the normal behaviour but didn't have any luck.

We ran out of time just as we were trying to figure out the last bit of your instructions, by "buzz out" do you mean monitor the voltage the whole way along the signal path between those points?

Let me know if the sudden "correct" behaviour triggers any other suggestions, and otherwise please accept my sincere thanks for your help so far.

Best wishes,

D :-)