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Subject: Odp: [PolySix] Re: PROGRESS!!!!

From: Roman <modular@go2.pl>
Date: 2016-02-13

MG, EG, VCO, VCA, EFFECTS, PROGRAM sections are on CPU board (middle one), while ARP, KEY ASSIGN are on voice board (right big one). So you know where to look... an entire CPU board...
It's really difficult to fix/troubleshoot a synth over email for me, there are folks that are briliant in this. I'm nore like in-person examination type. So here are a couple of my wild guesses:

Check if the control panel is scanned correctly, or scanned at all. Put your scope probe to pin 1 of CN11 on CPU board and see if there's weird waveform, that can change little segments while you move any pot from the panel. There should be shielded cable there on pins 1-2, service manual somehow shows this both ways so I'm not sure if pin 1 or 2. Other pins on this CN11 should show square/pulse waves.
Then check pin 1 of IC 27, there's even a testpoint for that originally on PCB. This should show even weirdest waeform, with more changes in cycle, but in sync to the pots wave described above.

Roman

Dnia 13 lutego 2016 08:45 jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> napisał(a):



Thus far the MG, EG, VCO, VCA, EFFECTS, PROGRAM sections have been unresponsive. Though the ARP, KEY ASSIGN and other basic functions seemed to work okay (and all voices seem to be more or less tuned (which is nice) even if I can only get the upper octave to work (one thing at a time right?) - SO - THAT BEING SAID - i thought i'd see if the reset and calibration procedure would set things right - so turning VR1 clockwise - i got everything to light up correctly - but when i remove the 56K resistor (was actually a 47K- hoping it was close enough) - there is no change in state (sad face)... so that's the current status.