1. Home
  2. Electronics Repair
  3. Willing to Pay for Proper Korg DW-8000 Analog Synthesizer Repair Diagnostic

Willing to Pay for Proper Korg DW-8000 Analog Synthesizer Repair Diagnostic

I am not getting proper audio out of an old synthesizer. If I bypass the board with the volume slider, everything works fine, but when the audio runs through the board in question (Korg KLM-663-1), nothing other than the occasional scratchy volume slider sound.

If necessary, I'd be willing to even pay a few bucks to any kind soul who would take a few minutes time to point me in the right direction of a fix (other than the obvious -- bad volume slider). The board looks simple and straightforward, but I am a rank amateur when it comes to tracing such a problem. I have both the service manual and a couple of photos of the suspect board. If I recall right, audio comes in on the connector on the right and leaves on the one on the left (might have that reversed).

formatting link

I'm pretty certain the volume slider worked just fine, before I replaced the battery for the patches because it did make noises, albeit random ones. My multimeter also detects resistance change on the slider when I move it up and down. One other strange thing I noticed is that when the audio is re-routed, the detune slider doesn't detune -- it seems to affect a parameter value -- a filter perhaps? The slider that is supposed to change patch data also behaves similarly -- no increase or decrease in patch or parameter value, but instead a change in the parameter value.

Reply to
evilaltima
Loading thread data ...

Is there a 'hard' reset for this unit? (The Kurzwiel 250 has a button inside on the CPU board, for example). If yes, do a hard reset first.

Reply to
PeterD

Thanks for your time and suggestion Peter. It seemed such a simple and elegant solution that could be easily overlooked that I was excited to try it out. However, the only reset procedure in the service manual I could find is the one to clear the memory for the patches, which I had done a number of times while reloading SysEx data. I tried it again for good measure (a couple of times even) and still nothing but a scratchy slider sound is produced when keys are pressed and the volume slider is moved.

It seems far fetched, but I suppose someth> On Tue, 16 Mar 2010 19:34:24 -0700 (PDT), evilaltima

Reply to
evilaltima

You could do that but the obvious thing is just to see if you can find a replacement slider.

Reply to
PeterD

Ya know, just from looking at the back side of the PC board I'd suspect that the relay might be part of the problem.

You might be able to pull the plastic cover off of it and manually operate it either up or down depending on which way it's stuck.

Jeff

--
?Egotism is the anesthetic that dulls the pain of stupidity.?
Frank Leahy, Head coach, Notre Dame 1941-1954

http://www.stay-connect.com
Reply to
Jeffrey D Angus

Yep, I've seen very similar relays in the old SAE equipment. Pop off the lid of the relay and use a burnishing tool to clean the contacts. That should fix it right up. In fact, before you even do that, just tap on the relay with it powered up and see if the sound doesn't come back to normal for a while. Of course watch what you're doing with the set powered on.

Good luck.

--
David Farber
David Farber's Service Center
L.A., CA
Reply to
David Farber

Thanks so much for the suggestions! I did initially think the relay might be problematic, but it has always has made a clicking sound when I powered it up. I still took the advice and cleaned it up a bit just in case there was a contact issue. Still no luck.

Another interesting thing --as well as having no volume and strangely behaving tuner slider, the arpeggiator slider also does nothing - just like the volume. When functioning, the arpeggiator slider slows and speeds up the red LED which correlates to the resistance of that slider and the speed of the arpeggiator. However, even though I can read it with my multimeter -- just like I can the volume slider, the LED speed does not increase or decrease perhaps indicating a common fault.

I'm at a loss to think what might be affecting the functionality of all three of the sliders. I thought maybe the IC on the board might have something to do with it, but looking at the PDF, although it could potentially be a source of no volume, I don't think it would affect the other two sliders.

formatting link
l

Thanks aga> Jeffrey D Angus wrote:

lid

Reply to
evilaltima

Can you post a picture of the schematic?

Tom

Reply to
tm

The schematic is here:

formatting link

The entire service manual is here:

formatting link

Thanks again to everyone who's tried to help.

Reply to
evilaltima

Is there, by chance, a relay on that board, to prevent the power-on pop from getting through to the amp?

If so, you might want to investigate that part. It is very common for these to go bad and only let volume scratch through.

Reply to
stickyfox

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.