Oooooft!!! (Broken MicroKorg)

LektroiD · Post by **LektroiD** » Thu Jul 02, 2009 2:26 pm

I've just opened my MicroKorg to find this:

I presume this is a 100µF / 10V electroylitic capacitor?

It would make sense only being 10V, since the PSU is chucking out 14.4V rather than 9V.

I need to stabilise the PSU and replace the broken component (I could possibly solder in a through-hole one in its place). I'm wondering what other parts might have been damaged along the way though?

LektroiD · Post by **LektroiD** » Thu Jul 02, 2009 2:32 pm

Ok, I've filled the unit with batteries. I put in a 100µF electroylitic (through hole) and shorted the fuse, but still dead.

Ideas anyone?

X-Trade · Post by **X-Trade** » Thu Jul 02, 2009 5:42 pm

This isn't an electronics forum.
Generally, if you have a hardware problem with a keyboard, the best thing to do is take it to an expert. Most people here can't help you're more likely to damage the thing more than good.

simple repairs and changes can work easilly and aren't too complicated, like replacing encoders/pots, fixing broken wires, but generally working on the PCB level is much more complicated.

Sorry.

LektroiD · Post by **LektroiD** » Thu Jul 02, 2009 10:09 pm

Thanks for the help...

So what's the point of this support forum then, if it's not support? Besides, I've seen people discussing electronics & repairs here on many occasions, so why shouldn't I be allowed to discuss it? Is my post-count not high enough for your standards?

Why take it to an 'expert' anyway, when I can do the job myself? I don't have a problem working on PCBs, since I've worked on avionics for the military. I personally wouldn't trust anyone with my gear after seeing some of the cowboy jobs I've seen in the past.

In that light, care to suggest a forum where I'm likely to get a decent reply?

X-Trade · Post by **X-Trade** » Thu Jul 02, 2009 10:38 pm

I'm just saying, that most people here won't be able to help you. There are one or two people, but there is still a greater chance of screwing it up.
There have in the past been people with a very small prior knowledge of hardware, asking how to fix something, completely prepared to just jump in at the deep end, which generally isn't a good idea. Clearly, not saying you are one of them.

AFAIK, only Korg have the actual service manuals and schematics, so it is very difficult to do fault finding for most products when you don't know what voltage is supposed to be there in the first place. (I have worked on hardware too)
I'm not bashing your post, I'm not saying you're not allowed to post, just saying that you're not highly likely to get any reply. I think you've already gone further than most people in attempting to repair the board.

99% of posts here tend to be about how to 'learn' to use the gear or asking for specific advice or purchase advice (or just to complain about features).
There IS sometimes a Korg presence on the boards particularly for newer products, but this forum isn't owned or run by Korg.

You could contact Korg, but then they'd probably tell you to bring it to one of their service centres...

I'm sorry if I offended you.

tmt · Post by **tmt** » Sun Jul 05, 2009 6:23 am

I understand why OP was put off by your initial response XTrade. I thought it was rather harsh and snooty when I read it too. Though after reading your second response I think I understand what your general point was since stating that you weren't out to offend him but rather just calling it like it is here in regard to finding any help with the nature of his question. Obviously, it could've been worded differently and avoided such misunderstanding.

Anyhow, LektroiD if you find anything out regarding your PSU's fried component, lemme know; I'd like to know if you were able to repair this. I'm not really sure what you meant by "(I could possibly solder in a through-hole one in its place)", so if you'd care to elaborate on that I'd appreciate the explanation. Also, do you know what caused this damage to your unit?

I might be picking up a microkorg that has a fried\damaged internal PSU, that is if I can find any more details about replacing it or having it repaired. Hopefully you'll find the answers you're looking for and can shed some light on my question. Thanks.

BTW: I'm also looking for the repair manual for the microkorg, and might know where to find one, but won't be of help if it's in Japanese! If I turn up anything, I'll let ya know.

LektroiD · Post by **LektroiD** » Sun Jul 05, 2009 7:21 am

tmt wrote:Anyhow, LektroiD if you find anything out regarding your PSU's fried component, lemme know; I'd like to know if you were able to repair this. I'm not really sure what you meant by "(I could possibly solder in a through-hole one in its place)", so if you'd care to elaborate on that I'd appreciate the explanation. Also, do you know what caused this damage to your unit?

It appears the cracked component is a tantalum capacitor. To solder a through hole component would be simple, just trim the legs down to fit the pads, splay them out and solder them on to the existing pads. I haven't yet done this yet (read further to see why).

For some unknown reason, the PSU started chucking out 14.4V, when it should be 9V, I have no idea why? As you can see the power rating of the components is no more than 10V, no wonder it smoked!

BTW: I'm also looking for the repair manual for the microkorg, and might know where to find one, but won't be of help if it's in Japanese! If I turn up anything, I'll let ya know.

I've done a search for the service manuals / schematics for this, but without any luck, I don't want to delve any further in without it. I think Korg's general rule is that they release the service manuals 4 years after manufacturing has ceased. Since MicroKorgs are still currently in production, I doubt you'll see a service manual. If you manage to find any, please PM me

To be honest, the more research I do on this matter, the more I have repeatedly seen the same fault with these machines, through no misuse of the end user. It seems there is no real protection in place on the circuit, the fuse is some way into the circuit (and surface mounted too), so all the components between that and the power input will fry if there is a surge of any sort. Therefore Korg should be looking to recall and replace the faulty units, as it is evidently a design problem.

I remember a few years back, Sony had a repeated issue with their Playstation 2 lasers failing, anyone with that problem was urged to take their Playstation in to a Sony centre for a replacement, (even out of warranty). Some tme later, the PSUs for the slimline PS2 were found to be faulty, and also recalled and replaced - free. Apple have done similar recalls on MacBook batteries, etc. This should be happening here, since the same repeated issue is reoccurring time and time again.

Has Korg announced anything of this nature? There are a lot of broken microKorgs out there, All with the same problem. It doesn't look good from a buyer's perspective knowing their MK could pop 2 months out of warranty.

philtipping · Post by **philtipping** » Sun Jul 05, 2009 6:56 pm

I'm tending to side with X-Trade a bit on this one as it's easy to go off on the wrong track and do more damage.
My (working) PSU also measures 14 volts, but this is when it's unplugged from the MK and is quite normal for an off-load measurement.
If your machine is not drawing any current (due to an MK fault), then you'd expect the voltage to be the off-load value, so your conclusions re. the PSU vs. the 10v capacitors may be mis-guided. An ammeter in series with the supply would show what's happening.
Good luck.... but be careful

Phil.

xmlguy · Post by **xmlguy** » Mon Jul 06, 2009 8:14 am

Component F1 looks fried. Probably a voltage regulator, which will usually be fried before any caps blow. Without a proper schematic, your best bet is to buy a working MK and trace the circuit with a scope to see what a working circuit is doing. Even so, when you blow up the main +V power rail, you'll usually take out a lot of other components with it, even though they might not show any external evidence of overheating. (take this on only at your own risk).