Korg Forums

Hi All,

I just got hold of a Korg M1 to go in my "rack of Korg" (Poly-800, Prophecy, Trinity and now the M1).

When I first turned it on the battery was dead, and everything was init program. After a while of being on it made a crazy digital squeal but I assumed that was because it had no patches. It did play the horrid sound fine.

I replaced the battery, and that seemed fine. But now everytime I fire it up it makes a horrid digital squealing sound through the output (headphone and all four outputs). The sound is controllable in volume via the volume control and seems to change when I fiddle with the buttons to change to program etc. Display and all of that seems fine.

I ploughed on and ran sysex of the patches back into the machine. That worked as I now have the right names on the programs. But still, nothing but the squeal from the outputs.

What is wrong with her?

TL;DR - Korg M1 - just makes a squeal sound but everything else seems to be fine. What is wrong?

Thanks!

Ed.

Just guessing but check your power supply voltages?

You should also check the mainboard for any leaking electrolytic capacitors - there are 4 of them. The leaking acid may cause a lot of issues - i.e. internal memory cannot hold data anymore due to a track on the pcb 'has been eaten up'. Look at this pic taken by me from my M1REX



- the acid (coming from C32) dispersed by flowing - it also crept under the DAC so I had to unsolder it, cleaning the pcb and put in a socket for the DAC - not to forget a trace I had to 'repair' due to being interrupted. In the end the unit works like a charm again. I suggest to replace all electrolytic caps on mainboard, put in a new battery (which you already did) and then: you should RESET the M1: turn OFF power, then press and hold the switches [INT], [CARD] and [COMBI] and turn ON the power again. The ROM version is indicated on the LCD screen and ALL data in M1 are initialized.
Thereafter you have to reload the sounds via MIDI.

Thanks - I'll open it up and take a look

Never was any good at soldering tho!