Strange Sounds from the M1

Megawilsound · Post by **Megawilsound** » Tue Jul 21, 2020 2:14 am

Hi all

I just got my self a second-hand M1.

There is a digital type sound that plays all on its own, without playing the keys.

I have provided a link to a wave file of this sound.

I have recapped the M1 so that is not the issue.

I am wondering if it is one of the ROM chips?

When I got it it did not have any of the soundbanks, so I did a Sysex reinstall, they all sound as they should.

Any info on what could be causing this issue would be good appreciated.

The link https://drive.google.com/file/d/1uKoVF9 ... sp=sharing

Thanks

Megawilsound

the_crimson_thunder · Post by **the_crimson_thunder** » Thu Jul 23, 2020 4:11 pm

Hi there,

so you said you already have recapped the synth - does that mean the PSU as well as the mainboard? I had a M1 with a leaking electrolytic capacitor (C32) where the acid crept under the ADC plus one pcb trace was disrupted by the acid! Check that if you haven't already...

Have you measured the battery's voltage? Maybe the coin cell needs to be replaced (it's already mounted in a holder). After a battery swap you should initialize the synth:

While pressing and holding the switches [INT], [CARD] and [COMBI] and then powering ON the synth the ROM version is indicated on the LCD screen and ALL data in the M1 are INITIALIZED!

Now reload the factory sounds or your own sound set via Midi from a computer.

I don't think it has anything to do with (one of) the ROM chips.

The latest firmware for the M1 (not the EX version) is v. 1.9

Megawilsound · Post by **Megawilsound** » Tue May 11, 2021 7:20 am

Hi the_crimson_thunder

Yes, I recapped the PSU and replaced the battery.

I spoke with a keyboard tech and was told it was most likely a faulty OP Amp I have replaced it with a new one, however, I can not test it as the PSU is not putting out the right voltages so I am looking to get this one fixed, another from a dead M1 or a modern replacement if I can find one.

Megawilsound

the_crimson_thunder · Post by **the_crimson_thunder** » Tue May 11, 2021 8:00 am

How did you measure the psu's voltage?

Since it is a switching power unit you can't measure its output voltages 'stand-alone'! Those psu's do need a certain minimum load for proper working. You must connect it to the M1's mainboard, then measure the output voltages...

Hth