Discussion about the Korg PolySix synthesizer

Hi Razvan,

I think there are two different problemes:
- KLM367 CPU not starting
- KLM366 Key Assigner behaving wierd

First thing ist to make the KLM-367 CPU start reliable. Check the power
supply for correct voltages and perform the reset circuit adjustment
procedure given in the service manual.
The test pulse at TP4 *is* in 20msec intervals. The pulse itself is
very short.
Check the resonator frequency at IC22 (CPU) pin 3. It should be ca 6MHz.

Second: The KLM-366 has a test mode as well. "It is started by jumpering
pins DB7 and P17 using a diode (cathode towards DB7) on the 8049
processor on the KLM-366 circuit board (this can be done on the
keyboard connector CN04). In this mode the CV DAC is set to generate
0V, 2.5V, or 5V depending on the position of the OCTAVE switch (16'
results in 0V, etc.)".
You can check this voltage at KLM366/IC9/pin1.
Check the reset signal. KLM-366 is in reset when switching to Tape
Interface mode. Check the resonator frequency. It should be like on
KLM-367 6MHz at CPU pin 3.

Do the buttons behave normally? (Porbably not...)
The BANK, MANUAL, and PROGRAM buttons operate on the KLM-367 Programmer
CPU, whereas the ARP, HOLD, UNISON, CHORD MEM, and POLY buttons operate
on the KLM-366 CPU.

Good luck,

Johannes



On 2012-12-04 20:27, arpm234 wrote:
> nobody ?
>
> --- In PolySix@yahoogroups.com, "arpm234" <arpm234@...> wrote:
>>
>> Hello,
>>
>> I've did some tests today and here;s what i found:
>>
>> TO CONFIRM: cpu seems to be working fine since i was able to see the clock on TP4 on osciloscope. Strege thing that somebody mentioned the gap should be 20 ms and i meassured 10ms. Is this ok ?  Also the TP2 spot looks ok - The multiplexed signal from the pots it is there.
>>
>> PROBLEM: there cpu starts randomnly. A few power off - power on cycles are necesary to get the clock there. I this this is related of the bad 4 x 74ls75 found on the control panel board. Two of these latches seem to be dead.
>>
>> PROBLEM: Altoought there is sound presend, and lfo, cutoff, and all the other pots are working, the sound is non interupted, very loud and at a rather high pitch. voice 6, 5, 4 diode leds are light up, and the sound resemnbles like a few vco beeing active. the other 3 leds, for voice 1, 2, 3 are off. touching the keyboard changes the pitch slighly but then resumes the state before. I'm suspecting the latches: 74ls75
>>
>> QUESTION: how to test the key assigner cpu ? Is there a method simillar to the uC found on KLM 367 ?
>>
>> Thanks for support guys.
>>
>> Razvan
>>
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