Discussion about the Korg PolySix synthesizer

I would also check the INTb pin, pin 6 and see if it's sitting low.   

If you turn on the test switch, and then power cycle the synth, if the CPU is working
it should go into a tight loop of code where it just converts channel 0  (Eff Spd/Int) and
chan 1 (filter cutoff) over and over in a loop.   You should see the DAC output change to follow
those two voltages as you change the pots.  If that is working, then the MCU is OK.

If it's not, then troubleshooting just that loop should be easier than the main control loop.

Bob

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On Sun, 7/3/16, noddyspuncture@hotmail.com [PolySix] <PolySix@yahoogroups.com> wrote:

 Subject: Re: [PolySix] Another P6 with all LED's lit....
 To: PolySix@yahoogroups.com
 Date: Sunday, July 3, 2016, 10:06 AM
       
       Yes Bob... pin 4 Reset is sitting 'high'
 (according to my logic probe) and I also measure 4.85v on it
 ... I can do the procedure successfully - adding the 56K
 resistor, setting VR1 so reset is just 'low' and
 when I remove the resistor it then jumps to
 'high'.
 All that
 works... so would you then say that my 8048 processor is
 good?Could the MCU be getting stuck because
 it's faulty or would another fault elsewhere cause
 that?Should I
 be looking elsewhere do you reckon?
 
 I am seeing a sine wave of
 about 50mV on 'T0' - 8040 pin1 - that's not
 right is it?
 
 Cheers,Tom