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Subject: Re: [korgpolyex] Re: POLY 800 MKII Drifting

From: ian r <ianpoly800@...>
Date: 2016-07-30

Measuring the circuit on the back of the joystick pcb, the -5V line measures at -4.38V. 


On Sunday, July 24, 2016 4:14 PM, "Michael Hawkins korgpolyex800@... [korgpolyex]" <korgpolyex@yahoogroups.com> wrote:


 
Start with your external power supply. Is it is right voltage and does it have a current rating 300mA or higher?
Then check that the power supply rails in the Poly itself are stable. measure at first power on then measure again a few hours later. Are they stable?

/Mike


From: "ianpoly800@... [korgpolyex]" <korgpolyex@yahoogroups.com>
To: korgpolyex@yahoogroups.com
Sent: Sunday, July 24, 2016 5:12 AM
Subject: [korgpolyex] Re: POLY 800 MKII Drifting

 
I thought I'd update, I never did solve the problem.  I ended up bringing the keyboard to a repairman, who thought he'd solved the problem replacing a couple caps, but fast forward $150 in repair hours and the keyboard still drifts. I left it for a week in the same spot and every once in a while would turn it on and watched it fall a few full steps.

The other day I left it on for an hour and a half and it drifted a quarter tone.

Does anyone have any ideas of what I should test in the guts?