Discussion about the Korg PolySix synthesizer

Hi to all I was wondering if anybody has pin out or data sheet for the ic 22 or info about testing the board with the chip out. mine gets warm after a minute or so and also the leds seem to work randomly I already found a bad ic 31 and replaced it as well as the batt/trace problems.

thanks

Ken

Hi Ken,

Ic22 is the microcontroller that basically runs the synthesizer. It has software inside, so you cant simply replace it with a new chip. You would have to get one from another unit. Testing the other circuits without it would be difficult, but not impossible. Since ic22 is tough to replace be careful when probing around it to not short anything to anything else. If ic22 is an NMOS part which it could be, it will get a little warm normally. If it gets hot to the touch, then it may be bad. If you have a scope, check the signals coming out of ic22 to see if they are swinging from 0 to 5 volts. You may see some intermediate levels on the data bus pins when they are floating. Thats ok. With a scope, its pretty easy to find signals that are either floating due to pcb eaten traces, or shorted, due to chip failures.

Good luck.


Bob

 here is the update I ohm checked all pins on ic 22 every thing except for ground and power supply was ether ol/infinity or above 1000 ohms. I checked all pins with o-scope and most were 5 volts no signal some were a little lower like 3.5 or so except for grounds that were 0 the chip gets hot in about 30 seconds so I have to test a couple pins and let cool. I am thinking the chip ic22 must be bad/shorted. but can I take this chip out of socket and test the board? should I have voltage on the data lines with the chip unpluged? 

thank you all for any help

Ken