Discussion about the Korg PolySix synthesizer

If reset is at 0.24V relative to ground, then the CPU is being held in reset.
It's an active low input, so it's active.   

Measure pins 5, 6, and 8 of IC5 please.

Pin 5 should be roughly 1.1 volts DC.  

Pin 8 should be 5.0 VDC +/- 0.1 volts

Pin 6 must be less than what you have at pin 5.

Also, make sure you have installed R35, as IC5 can only pull 
reset low.    The resistor is needed to pull it high when the IC is not
pulling it low.   (Google "open collector")

If reset is asserted to the CPU, there is no point to look at any 
other CPU pin except the two oscillator pins (with a scope, not the meter)
and the power pins.  So 2,3,40, and 20.     Check all 4 of these with the scope
and tell us what you see.   

But it won't run until you get the reset issue sorted out.

Bob

   
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On Mon, 2/8/16, jw_dewdney@yahoo.com [PolySix] <PolySix@yahoogroups.com> wrote:

 Subject: [PolySix] Re: The Post I wanted to make....
 To: PolySix@yahoogroups.com
 Date: Monday, February 8, 2016, 11:54 PM
 
 
  
 
 
 
   
 
 
     
       
       
       HI Bob - sorry it took me awhile to dig the scope
 out and find the probes etc. 
 So - I got it
 all up and running and damned if i can see a signal
 ANYWHERE. From both TP4 and from the RESET (pin 4 according
 to the drawings i found) I get only positive DC offset and
 no pulses whatsoever. I double checked my with my Tek TX1
 dmm - which does a nice job as a frequency counter also -
 and from TP4 I got 0.004 Hz (meaning zero) pulse activity at
 plus 4.9v offset... and from the reset pin I get about
 0.24mV dc offset (positive). I'm getting positive
 offsets of betwen 1.5 and 5 volts on nearly every pin on the
 CPU. TP1 gives me 0.6-ish volts positive - so maybe
 that's got SOMETHING to do with it? Not sure. Still
 driving me crazy why that should be... I'm trying to
 follow the circuit back to the power connector but get a bit
 lost when i do...
 
     
      
 
     
     
 
 
 
 #yiv3082498721 #yiv3082498721 --