Korg Poly800/EX800 Users

First, how do the power supply voltages look?


Mike



________________________________
From: Malte Rogacki <gacki@...>
To: korgpolyex@yahoogroups.com
Sent: Thu, December 31, 2009 4:15:52 AM
Subject: [korgpolyex] Trying to fix two broken Poly-800

  
Hello everyone;

new group member here. I've recently aquired two non-working Poly-800 which
I'm trying to repair now.

#1 is an "inverted" model, without a battery on the main board (but with
the solder pads for it) and without a KLM-601. #2 has both the battery and
the KLM-601.

#1 occasionally powers up so that the display lights up; however it doesn't
react to any button presses and makes no sound. About 50% of the time not
even the display works.
I've observed RST 5.5, 6.5 and 7.5 and they look pretty normal so far. What
somewhat irritates me is that the CPU clock looks more like a sine than
like a rectangle. Is this normal?

#2 seems to have a problem in the RESET circuitry; pin 36 of the CPU reads
only around 1.9 volts which I believe is not sufficient. The CPU clock
looks more or less "sinusy" here as well.

I would be most grateful for any ideas how to get them running. Right now
I'm planning to move IC40 from #1 to #2 to see if that helps things with
the RESET line.
The material in the files section of the group has already been of major
help here.

Thanks and best regards,

-- 
Malte Rogacki