KORG M1 - No sound / Low battery indication. SOLVED!

[Yekuku]

Did you visually check all resistors as well or test them all?
Does measuring resistance change with polarity?

If my memory serves me right, I did not check for any faulty resistors, I inspected the board visually and I noticed that a discolored resistor had gone up in value, by replacing it the problem was gone.
It does not matter where you put the multimeter probes when measuring resistance, readings should not change.
good luck !

[Mooger5]

There is one problem though...
I installed factory sounds and i am having a slightly distorted output.
Most sounds play ok, but many loud patches distort like there is an internal clipping going on, that happens even when I lower the volume slider. this problem is more obvious when playing chords, as the velocities of many notes are added, sound gets easily clipped internally.

Well, my M1 is alive and kicking again:)
After replacing C23 ( 220uf @ 25v) in the power supply board (KLM-1269) I noticed a discolored resistor (R79 @ 10 Ohm in the DAC board (KLM-1261), which was causing the distortion.
After replacing the resistor the output is crystal clear again

Thanks for this. Not the same engine but my newly acquired Kawai K4 has the same symptoms you´ve described.

[Yekuku]

Hi Mooger5 , I am glad that the info that I have posted was useful to you.
Resistors rarely go up in value value unless they are overpowered , usually it is sth else that triggers this behavior.
Did you find the culprit that is causing the distorted output on the K4?

[Mooger5]

Hi. Not yet, wasn´t sure it was a fault or just part of the "character". I´ll have a look iniside later. It´s probably being underpowered and the PSU is unusual (+9/+5/unknown), so I better study the schematics thoroughly before attempting anything else.

[Yekuku]

I had a quick look on the schematics, it is an odd psu indeed.
I wish I could help more, but i have no experience on the K4.
Good luck man !

[Mooger5]

Thanks! When you find one, try it! If you´re into old-school ambient you´ll find this synth is special, like secret weapon special.

Cheers!

[Mooger5]

Well, after much testing I came to the conclusion the distortion was only caused by bad programming. The individual channels' levels must be kept low and that's it. Factory presets confirm it.

[WORKSOP]

According to the schematics , the green thingies are inductors, 47uH.
Inductors rarely fail, you better replace C21 , it is bulged.

The L4 one on my board has failed, you can see the damage like corrosion around the bottom, I'm familiar with capacitor replacement (the blue type) but haven't come across this component "inductors" any help sourcing some replacements

I replaced the battery and installed the sounds, that worked but obviously no sound please help any one?

[Yekuku]

Hi WORKSOP and welcome to the forum.
I cant see the photo that you have posted , so I cant help much.
The L4 is an inductor (coil) and when coils fail they dont produce corrosion , they are either "open" or partially shorted.
Have you done a factory reset after the battery replacement ?

[WORKSOP]

Hi WORKSOP and welcome to the forum.
I cant see the photo that you have posted , so I cant help much.
The L4 is an inductor (coil) and when coils fail they dont produce corrosion , they are either "open" or partially shorted.
Have you done a factory reset after the battery replacement ?

Thanks for the welcome nice to meet you, yeah the inductor has corroded looks like the "glue" has had a detrimental effect over time and made it corrode.
I have replaced the battery and reinstalled the sounds, but it still came up with the low battery message, thats when I looked and you can see the damaged inductor thing, the capacitors all look fine, I have changed these before on a TV but havent got any experience with the inductors. I have taken the board to an electronics guy I know hes going to have a look hopefully he will get it working.

[Yekuku]

If you could post a picture , it would be easier for me to understand whats going on.
The glue that is used to hold components in place, sometimes gets corrosive and destroys surrounding parts.
Did you check the voltages on the power supply ? (+12V/-12V/5V )
Good luck !

[WORKSOP]

Great news the M1 is fully working again, power supply sorted by an electronic guy £20 then I had the distortion from the DAC board the ressister was burnt out changed it and like I say perfect working order.

Thanks for your help and giving me the confidence to do it myself. Great forum and people a keeper

[Yekuku]

I am glad I could help ! Enjoy your M1 !

[synzoneau]

This thread came in handy with Korg M1 repair I did recently. I cleaned up the glue and changed three resistors a 2x560R, 220R, and rectifier diodes D6 and D7. All the caps were fine. Symptoms were machine would randomly reset and after an hour of playing the sound becomes intermittent probably because of a 12v line dropping out.

[flyingsaucer]

First all thanks a lots for this wonderful FORUM/TOPIC I would do a clean full recap of my KORG M1, I've bought it second hand in 1997 I think that's more older than 23 years; Korg M1 serial number is 075744.
I've some question for expert please be kind... I'm not an expert technician but I know how solder and desolder components.

Here it is my power supply KML-1269 perfectly working I'm posting some pictures also for helping reference.
I've bought a full recap kit from ebay but the kit it's missing some capacitors.

This is my power supply
http://imgbox.com/kmN7GnCN

Someone could please explain how to remove resine without making damages?

http://imgbox.com/xkLPHlqt

http://imgbox.com/Uihh8Lh8

More resine/glue near COIL

http://imgbox.com/bOlLjdJo

This is the kit I've bought from EBAY but there are not correct capacitors about power supply and missing I've created a list of missing parts.

http://imgbox.com/qbsp0yL8

Missing cap in the KIT:

KLM-1261 BOARD DAC
Number 8 NON POLARIZED 10 Microfarad (µF) 16v

KLM-1269 BOARD POWER SUPPLY
Number 1 POLARIZED 47 Microfarad (µF) 400v
Number 4 POLARIZED 220 Microfarad (µF) 25v

KLM-1262C BOARD TACTILE BOARD
Number 2 NON POLARIZED 22 Microfarad (µF) 16v
Number 1 NON POLARIZED 1 Microfarad (µF) 50v

KLM-1266-6 MAIN BOARD
OK
------------------------------------------------------------------------
It's a good idea to recap also NON POLARIZED capacitors?

Also these big brown need to be recapped?

http://imgbox.com/gkoaRtMa

In the kit there are also these two little yellow capacitors I think.....where they go?

http://imgbox.com/bzz7wZbu

Meanwhile I'm repairing Tactile Yamaha contact desoldering a 12 notes group, 1 note is completly broken.
Waiting for a new spare part.

http://imgbox.com/0g0CvH51

http://imgbox.com/PR2rwQAc

I would also change all tactile button and leds which led I need to buy?

Thanks a lots everyone for helping.