There is a possibility that this problem is something relatively straightforward to diagnose such as a drooping power supply. However, my suspicions are that it is more complicated than that, and may involve trying to find somebody who knows the insides of an MS200R to offer help.

If it's not the power supply output voltage drooping low, the sort of thing that could cause increasing slowness to respond is a microprocessor interrupt that is failing to clear correctly. If it's more intermittent than that, and in particular if the problem changes in response to mild percussive therapy (forcefully tapping it), it could be an internal connector making poor contact.

I've not been able to find any internal details such as circuit diagrams (schematics) on the internet, so it's difficult to be more specific. It's worth taking the top or base off the unit and measuring a few power rail voltages with a multimeter. You could also use the handle end (not the blade end) of a screwdriver to nudge and tap the boards while powered up to see if the box symptoms change.

Do come back to us with what you find, and we will try to advise further, but it's likely that this is going to be a tricky one.

Hi Boswell..

I don think it's the power supply. Only because a)I've had the same setup with no chage for atleast 1.5-2yrs and b)because the unit is native U.S, I am running it though a step down transformer, so it's getting juice..

"However, my suspicions are that it is more complicated than that, and may involve trying to find somebody who knows the insides of an MS200R to offer help".

I have been trying for a while. I first started looking when I noticed the problem. 6 months of intermittent checking and...nothing yet..

"If it's not the power supply output voltage drooping low, the sort of thing that could cause increasing slowness to respond is a microprocessor interrupt that is failing to clear correctly. If it's more intermittent than that, and in particular if the problem changes in response to mild percussive therapy (forcefully tapping it), it could be an internal connector making poor contact".

Again I don't think it's this because the buttons do work..Just before the crash, I had an (arp) on and all the lights were working..and all 16 pads couldn't crash at the same time..plus I was switching between sounds via the 1-16...and can still switch between sounds via 1-16..its just that theres no sound output..

"I've not been able to find any internal details such as circuit diagrams (schematics) on the internet, so it's difficult to be more specific. It's worth taking the top or base off the unit and measuring a few power rail voltages with a multimeter. You could also use the handle end (not the blade end) of a screwdriver to nudge and tap the boards while powered up to see if the box symptoms change".

Since university (15 years ago), I haven't even looked at a circuit board lol..Never been that confident with the electronics part of "Audio"..
I've tried contacting Korg dealers in Sydney and Australia, and no one seems to know what's wrong..I can't even get a proper suggestion. I've had way better info and ideas from boards..hmmm..Whenever the techs get stuck, they do the usual: "Well you can post it to us. We can look at it for you, but even if we don't find anything, you still have to pay".
I can't believe in 2012, there aren't more qualified techs working in Australia. I know this is a pretty specific problem, but for all the major Korg "techs" to have no idea.... :(

Well that's my rant..

Thanks for the suggestions..I guess I have to keep plugging on... :(

I've just now located a copy of the service manual for the MS2000(R), so at the weekend when I get back from my current road trip I'll get hold of it and have a look through the circuits to see if there is anything I can suggest to check specifically.

Thank you Boswell. That's kind of you.
I decided to experiment and see about the "MIDI loop check error". I connected the MIDI in and out together. I ran the on+modkey+3..
The test started up..
1.Dsp Dram Check (passed I guess),
2.Midi Loop Check - Started with noise then passed I guess
3.Then for a very short time, a blank screen came up.
4.SW & LED test all led on. All the lLEDs lit up because I pressed the cursor button and the next menu was,
5.Sys Rom check
6.SW&LED test Audio In1 (I patched cd out (patchbay) into Audio In1 and sound came through left channel after turning Audio1 pot up-headphone out), then I pressed the cursor button and the next menu was
7.Same for Audio In2..Right channel though. I pressed the cursor button and the next menu was
8.Then the Osc1, Osc2 etc..

I think this testing is a program based "self check" diagnosis to see where a problem might be.

Now I am stuck at SW&LED test..21 arp ran (tempo pot). I turned the pot left to right fully, and the red light stays on.

Any ideas? At least this might be some kind of indicator.

Also I recorded the sound during the MIDI loop test. Caution: It's a high pitched and loud..(https://rapidshare.com/files/3058819297/MS2000R_Sound.mp3)

OK, I'm back from my travels. Thanks for the sound sample, but at the moment I can't decode a great deal from that. The unfortunate thing is that you can't tell whether the waveform is produced because of the fault or whether this is normal behaviour during the running of the self test.

Probably a better clue is the self-test sticking at test 21. This could be caused by a faulty tempo pot, a damaged multiplexer (these scan 8 pot outputs and reduce them down to a single line) or a more complicated fault in the microprocessor system. If you can, I would put a multimeter on the wiper of the tempo pot (VR35) relative to ground (the sleeves of the I/O jacks, say), and check that you get a voltage that varies from 0 to 5 as the tempo pot is turned clockwise. If you do, then the pot is OK, and the fault is further down the chain.

If the HC4051 multiplexers are in sockets, you could try exchanging IC4 and IC3 (with the power off!) and see if the self-test then stops at the Oscillator 2 tune pot. If it does, you have a faulty HC4051, and there is a good chance that correct operation will be restored by replacing it.

My suspicion is that the problem is a little deeper than this, but it's worth trying the simple things first.

Hi Boswell,
I'll try to ask one of my friends if he can do the tests for me. I'll text him tomorrow and see what he says. Might take a while because he is real busy, but at least it will get done.
I wish I could do the tests/repairs, but I'm really not confident with elecrtonics, and I don't want to mess it up further.
I'll let you know what he says.

Thanks..:)

sys_rom check

Hi,

during test procedure I get the message "SYS_ROM check ChkSum Error".
Tried updating the software to 1.07, same result.
Downgraded back to 1.05, same result.
The main problem I'm trying to fix is that there is a lot of cracking noise in sound output. Only during playing. I suspect it will be the famous DSP problem (involving the complete replacement of the KLM2167 board), but can't get the error message ...
Thanks!

Wolfo, am I right in thinking you have found this topic because you have a problem with your MS2000R and you have no connection with Amy in Sydney?

It's sloppy programming if the firmware update process does not checksum the result of writing a new image to the ROM, but not unknown. The fact that you get a mostly-functional system after re-writing the firmware indicates that the error is probably not in a code section of the ROM, and is also likely not to be connected with the noise in the output. Crackling like that is usually the result of a faulty component in the audio section, a dry joint or flakey power rails.

I saw in the Korg MS2000 forums about the [[url=http://[/URL]="http://launch.group…"]"famous DSP problem"[/]="http://launch.group…"]"famous DSP problem"[/]. Your trouble could well be overheat damage in the DSP, but if the ROM checksum error is in a section of DSP code, that could be the cause.

Hi!
You're thinking right :) I don't know Amy, in fact, I don't know anyone in Sydney: I'm from Belgium.
The test procedure is very poor documented in the service notes, it just says literal "SYS_ROM check" next line "ChkSum Error".
As for the firmware updates: it does what it's supposed to do according the update procedure. Some messages are displayed, lights go on, on the end everything dims and the computer says it's successfull. Power cycle the ms2000 and it boots.
I have basic electronic skills (I can use a multimeter and a soldering iron), but the schematics of this device is above my knowledge. (I recently repaired a Juno-106, and as far as it's the analog circuit I understand the basics)
Are you willing to point me out? What should I measure, where, ...
Thanks in advance !

I don't know that I can be a great deal of help here as I don't own an MS2000(R), so am not in a position to try re-flashing it or to look at waveforms. The Yahoo Korg MS2000 group has several tales of owners seeing the "ChkSum Error" message on updating the firmware. However, their units seem to work OK afterwards, so I'm not sure that the error message is related to the clicks and noise in your case. I'll have a look at the schematics to see if I can spot anything that you could check.

Hi,

Thanks in advance! I'm quite convinced it's not a software / flash problem.
A user on a Dutch forum suggested the audio in has been shortcircuit/overloaded (because audio in is on osc1), but I'm not sure about this as the problem occurs on every waveform :(