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From: PeterD on 17 Mar 2010 08:51
On Tue, 16 Mar 2010 19:34:24 -0700 (PDT), evilaltima
<evilaltima(a)yahoo.com> wrote:

>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).
>
>http://picasaweb.google.com/102938678257682832185/KorgDw8000#
>
>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.

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.
From: PeterD on 17 Mar 2010 19:24
On Wed, 17 Mar 2010 13:25:23 -0700 (PDT), evilaltima
<evilaltima(a)yahoo.com> wrote:

>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 something could have happened to
>the volume slider during my battery replacement. I've tried already
>tried deoxit, but perhaps there a simple way I can bypass the volume
>slider completely to test it other than replace it? IE, Can I insert
>something into the circuit that sets the resistance open at full
>volume? Again, please forgive my electronics naivete if that sounds
>ignorant or uninformed, I'm an unemployed philosophy major by trade.
>

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

From: David Farber on 17 Mar 2010 22:16
Jeffrey D Angus wrote:
> evilaltima wrote:
>> I am not getting proper audio out of an old synthesizer.\
>
> 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

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


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