Korg DW8000 issues

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Re: Korg DW8000 issues

Postby Grimepoch » Mon Mar 24, 2014 7:14 am

I recently got a DW8000 as well and it has a strange problem. It runs for awhile, then, it shorts the AC line and cycles my UPS after awhile. I am assuming it must be some sort of short that happens after it heats up. I've been trying to see if anyone else has seen the same type of fault, but not finding anything.

Is there anything else that can cause this sort of thing? It plays fine until that point. It usually takes like 5 to 7 minutes before it shorts out.

Thanks!
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Re: Korg DW8000 issues

Postby Algorithm » Mon Mar 24, 2014 4:20 pm

when you say UPS you mean "universal PSU"? do you still have the original PSU in it?
have you changed anything on this PSU?
Is it trash or treasure?
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Re: Korg DW8000 issues

Postby Grimepoch » Mon Mar 24, 2014 5:09 pm

When I say UPS I mean a battery backup system in my studio (Think like APC). My entire studio runs into 2 2000VA UPS systems. After the DW8000 has been on for like 5 minutes, it shorts the mains out and the UPS starts cycling on and off (I am assuming because the PS is cooling for a brief second, then expanding and shorting). Until I pull the plug out of the back of the DW8000. The DW is stock untouched. Got it from the original owner who bought it brand new so no mods or fixes of any kind done to it.
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Re: Korg DW8000 issues

Postby Algorithm » Mon Mar 24, 2014 6:37 pm

I see UninterruptiblePS . That is stuff I cant explain. Well, I might be able to give an idea.

From what I read here (I have no experience with battery backup systems really)
"The BU works pretty well as advertised, but it also monitors "power quality." That means when you have dips and spikes in voltage -- not very large, but they always occur -- your BU can interpret them as a danger to your system, and it reacts. It's really aggravating when it shuts your computer down when no power loss has occurred. "

I suppose maybe if the PSU in the DW8000 had spikes, it might be able to do that?
I know my dw8000 read a great deal fatter on a few PSU lines before it was repaired..
The PSU probably needs some parts replaced if it hasnt already been done.

The caps might have leaked on the PSU.
They did on mine. Made a mess, looked like some dried up ghostbusters film set ish.

Maybe the bridge rectifier on the PSU?

BTW, capacitors have gaskets on the bottom. Sometimes they shrink or crack, depending on how cheap they are.
The gasket cracks? then it leaks out the bottom instead of the release valve slits on top. Much messier...
It happened to my dw-8000.

You could try plugging in the dw8000 on a different circuit and seeing if it tripped a breaker or blew a fuse.
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Re: Korg DW8000 issues

Postby rschnier » Tue Mar 25, 2014 2:29 am

The theory about a spike on the line causing the UPS to reset, has some validity.

If the DW is truly shorting out the mains input (as opposed to just causing a spike on the line that causes the UPS to reset), it's most likely the primary winding of the power transformer in the DW that will be the culprit. (I'd expect you'd also be seeing a puff of smoke coming from the transformer in this case. Also it would be fairly unusual for a dead short like that to "unstick" itself -- more likely for the windings to weld themselves together and the synth would no longer work after that.) The primary winding, and secondary winding also, are wound with wire that has just varnish as its insulation, and sometimes that insulation fails, causing a short. But like I said, that kind of short is almost always a dead short from then on and it does not go back to normal, as your synth is doing.
-- R.
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Re: Korg DW8000 issues

Postby rhino » Tue Mar 25, 2014 2:33 am

Check the regulator ICs on the heat sink. The originals had a habit of dying after 20 years.
They are 7805 (3) and 7905.

ALSO - CHECK that some fool has not jumpered the fuse - Should be a 0.75 amp.
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Re: Korg DW8000 issues

Postby Grimepoch » Sat Mar 29, 2014 12:13 am

Thanks everyone for all the tips, I am going to crack it open in a few days and I will report back what I find! That way, if others experience this, they'll have some ideas of what to try.
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