Korg Forums

pafufta816 · Joined: 23 Mar 2007 Posts: 26

wow, that was quite a professional job. i'm glad getting the parts worked out for you. this seemed for a while to be a situation that might not be solvable.

djxkennedy · Joined: 10 Jan 2008 Posts: 1

Anyone else have any success with this? Looks like "Parts Is Parts" doesn't even carry those parts anymore.

Anyone buy extras and want to sell them? Any pointers out there?

LFR analog · Joined: 12 Feb 2008 Posts: 4

Is anyone still reading this thread? I am currently fixing a microKORG with all the previously mentioned problems with readily available (and fairly inexpensive) parts from a well known supplier. I already got the Vreg circuit up and running, but it looks like I'm going to have to do the CPU replacement too. I can post pics of the fix and a BOM here if somebody replies positively. Lemme know!

philtipping · Junior Member Joined: 11 Jan 2008 Posts: 93 Location: UK

My MK is ok currently, but I'm always interested in fixes 'just in case' so post away ... and many thanks for offering to share the info. Very Happy

Good luck with the CPU soldering; I thought I was doing well re-soldering a 16-way ribbon cable on a Psion 3 organiser, but take my hat off to the master emberdark Cool

Phil.

LFR analog · Joined: 12 Feb 2008 Posts: 4

Well it all started when I was talking to my local KORG service dude, and he said all replacement parts are unavailable that I needed. This included the voltage regulator, mosfet, and fuse. The Renesas H8 CPU is still sold commercially, however, but I had to create a different voltage regulation circuit to power this thing. I'm not sure if I can say where I ordered all my parts from on this forum, but it rhymes with "PigiKey".

parts:
-Renesas H8/2300 MCU ROMLESS 128 pin
-2.00 A 1206 size very fast blow fuse
-LM2592HVT-3.3 simple switching regulator (I got TO-220 package because it's easier for my lazy hands to solder and replace if needed)

I soldered a 33 uH inductor (i found it lying around) between the "feedback" and "output" pins of the regulator for inductive energy storage, and hooked the Vin, Feedback, and Ground pins to the correct locations. I wish I could show a valid photo, but the person I bought the broken microKORG from must have gotten in WAY over their head on this repair. It looks like he/she gouged the fried regulator out with a hot spoon. it really is that bad. Anyhow, this regulator eliminates the need for an auxiliary MOSFET for power, so it was a simple fix. I'm currently in the process of replacing the fried CPU, so I'll let y'all know how it turns out when it turns out. I'll check back regularly, so if anyone wants more specifics, lemme know.

Clauzii · Joined: 10 Jan 2008 Posts: 20

LFR analog · Joined: 12 Feb 2008 Posts: 4

Clauzii,

I'm still trying to find the time to fiddle with replacing the CPU, but here's a quick list of the parts I used. the voltage regulator is not anything remotely near a "drop-in replacement" as it has a MUCH larger package than the original, but as I explained before, all you need is a 3.3V switching regulator that can handle 9-12V input (read the datasheet).

description / digikey part#
IC H8S/2300 ROMLESS 128QFP / D12320VF25V-ND
FUSE 2.00A 1206 VFAST SMD / MFU12062.00CT-ND
IC REG SIMPLE SWITCHER / LM2592HVT-3.3-ND
CAP TANTALUM 100UF 10V 10% SMD / 495-2220-1-ND

**keep in mind that I also added a 33uH inductor to the regulator, and that should be easy to find.

Let me know how your fix works out!!!

--LFR

wizdomcube · Joined: 12 May 2008 Posts: 3

i bought a broken microkorg and was wondering where to get some parts. the screen doesn't work, and i wanted to figure out where to buy a replacement if there is such a place, and also there is no sound output, and i was wondering if you might now the cause of this and/or what parts i might need to fix it. this might be unfixable, but hopefully i can figure out how to repair it. thanks for any help you might have..

edit:the screen doesn't light up, as in it might work, it's probably a problem with the power, i don't think i'll need a new screen, but i was checking out that site, and i'm wondering, is this the screen that i would need... (the second one)

http://dkc3.digikey.com/PDF/T082/2411.pdf

wizdomcube · Joined: 12 May 2008 Posts: 3

anyone?

xoc3 · Joined: 21 May 2008 Posts: 2

howdy everyone?

i've got problem with my mikrokorg too, seems like they don't hold up much Evil or Very Mad

anyways, i turned it on after really long time, couple months, and the big PROGRAM SELECT knob works strangely. MK starts in program A11 or B11 no matter the position of this knob and when i turn it either way it jumps to x5y (where x is either A or B and y is 1thru8, depending on my fidling prior to turning the knob) and it stays there no matter where i turn this knob again until i turn off and on whole synth and then the same repeats Sad

and then the PROGRAM NUMBER 5 key Doesn't work at all as well as OCTAVE SHIFT UP key and three white and two black keys.

anybody knows before i gut it out, PLEASE? thnx

philtipping · Junior Member Joined: 11 Jan 2008 Posts: 93 Location: UK

Might be clutching at straws but just make sure there are no midi cables plugged in before you write if off. You can get strange effects if you have a midi feedback loop.
Phil.

LFR analog · Joined: 12 Feb 2008 Posts: 4

have you tried a system reset to restore the factory settings?

Procedure:

1) Hold down the SHIFT key and press
the 7 key.
The display will indicate " ."

2) Turn the 1 knob to select the data that
will be restored to its factory-set
condition.

1Program ( ):
Load only data for one program.
Program ( ):
Load data for all programs (128
programs).
Global ( ):
Load global data. (p.5 Cool

To cancel, press the lit SHIFT key.

3) If you selected 1Program ( ) in step
2, turn knob 2 to select the program
(A.11–b.8 Cool

that will be restored to its
factory-set condition.

4) press the blinking 7 key. The Preload
operation will be executed, and the
microKORG will return to its normal
state.

Note:
If you have not selected the data to be
restored to the factory-set condition
(steps 2 or 3), the 7 key will be lit. If
you attempt to execute by pressing the
7 key in this state, the display will
indicate "---" and the operation will not
be executed.

xoc3 · Joined: 21 May 2008 Posts: 2

wizdomcube · Joined: 12 May 2008 Posts: 3

ok, so i recently pulled out my microkorg to see what was really wrong with it and i've dicovered that i am getting the line in leds to light up for a few seconds and then they quickly fade, i originally thought that this was because it was losing power, but now i realized that when i plug in a guitar to the line in and play the guitar the led lights up when i strum, so i know it's on and working, i think i'll need to replace the 3.3v switching regulator, but can anyone help me and let me know what other parts i might need? i won't mind if it isn't really working properly i only need this thing as a midi controller so whatever will get the midi working is fine with me... help would be greatly appreciated.

LektroiD · Joined: 08 May 2009 Posts: 12

I posted this elsewhere, but didn't seem to get anywhere. However, this looks like a more appropriate thread.

I've just opened my MicroKorg to find this:

I presume this is a 100µF / 10V electroylitic or tantalum capacitor (since it's polarised)? Can someone please confirm this.

It would make sense being blown to bits like that, only being 10V, since the PSU is chucking out 14.4V rather than 9V for some reason (genuine Korg part).

I've filled the unit with batteries. I put in a 100µF electroylitic (through hole) and shorted the fuse, but still dead. I'm wondering what other parts might have been damaged along the way though?

Ideas anyone?