Korg Poly800/EX800 Users

Hello,

I'm still trying to fix my dead Poly 800's; and I've made some progress.
I'm still trying to figure out the various revisions and related boards.

#1 (working): "old" revision (without battery solder pads), KLM601
#2 (partly working): new revision (with solder pads) but no battery
pre-installed, no KLM601 or 601a
#3 (non working): new revision with battery installed, KLM601a

#2 works actually pretty well; however Master tune would not work and the
joystick would make some problems (bending only upwards, bend range only
zero or full). Close inspection reveals that R159 is not installed here;
however the PCB looked as if no KLM601/601a was ever installed before.
Strange.

Since this part in the schematics is very hard to decipher here are my
questions:

1. Am I assuming correctly that for KLM-601 to work R159 has to be present?
Or is a wire jumper needed instead? I don't see how the Master tune would
otherwise be connected at all...
2. Does the absence of R159 indicate that originally a KLM-601a was to be
placed here?
3. Could KLM-601 be just omitted at all and instead R159 be used?

Thanks,

Malte

Hi Malte,

sorry for the delay in getting back to you. I have an original EX-800 service manual and that section is much clearer. So if you still need help, let me know and I will have a look at it and let you know the details. I think your thinking is correct in that you need R159 or otherwise master tune cannot work.

Mike.

--- In korgpolyex@yahoogroups.com, Malte Rogacki <gacki@...> wrote:
>
> Hello,
>
> I'm still trying to fix my dead Poly 800's; and I've made some progress.
> I'm still trying to figure out the various revisions and related boards.
>
> #1 (working): "old" revision (without battery solder pads), KLM601
> #2 (partly working): new revision (with solder pads) but no battery
> pre-installed, no KLM601 or 601a
> #3 (non working): new revision with battery installed, KLM601a
>
> #2 works actually pretty well; however Master tune would not work and the
> joystick would make some problems (bending only upwards, bend range only
> zero or full). Close inspection reveals that R159 is not installed here;
> however the PCB looked as if no KLM601/601a was ever installed before.
> Strange.
>
> Since this part in the schematics is very hard to decipher here are my
> questions:
>
> 1. Am I assuming correctly that for KLM-601 to work R159 has to be present?
> Or is a wire jumper needed instead? I don't see how the Master tune would
> otherwise be connected at all...
> 2. Does the absence of R159 indicate that originally a KLM-601a was to be
> placed here?
> 3. Could KLM-601 be just omitted at all and instead R159 be used?
>
> Thanks,
>
> Malte
>

Hi Mike,

thanks for the offer; I think I have figured it out now.

KLM-601 and 601a are almost identical. KLM-601 was used in earlier
revisions of the Poly-800, KLM-601a in later revisions of the Poly-800, the
Poly-800II and possibly the EX-800. The Poly-800 service manual does not
mention the 601a at all, only the 601. But the the Poly-800 service manual
also does not mention a memory backup battery so it might cover only the
early revisions.

KLM-601 regulates the joystick bend range (VR1 and VR2); KLM-601a does this
too and in addition regulates the Master Tune range (VR3). R159 is required
for a KLM-601 board. When using a KLM-601a board R159 is NOT required; R3
on the KLM-601a board is used in its place.

As to why one of the Poly-800's did not have either a 601 or 601a installed
- that's a mystery to me. I'll probably build a replacement 601a for it.

> sorry for the delay in getting back to you. I have an original EX-800 service
> manual and that section is much clearer. So if you still need help, let me
> know and I will have a look at it and let you know the details. I think your
> thinking is correct in that you need R159 or otherwise master tune cannot
> work.
>
> Mike.
>
> --- In korgpolyex@yahoogroups.com, Malte Rogacki <gacki@...> wrote:
>>
>> Hello,
>>
>> I'm still trying to fix my dead Poly 800's; and I've made some progress.
>> I'm still trying to figure out the various revisions and related boards.
>>
>> #1 (working): "old" revision (without battery solder pads), KLM601
>> #2 (partly working): new revision (with solder pads) but no battery
>> pre-installed, no KLM601 or 601a
>> #3 (non working): new revision with battery installed, KLM601a
>>
>> #2 works actually pretty well; however Master tune would not work and the
>> joystick would make some problems (bending only upwards, bend range only
>> zero or full). Close inspection reveals that R159 is not installed here;
>> however the PCB looked as if no KLM601/601a was ever installed before.
>> Strange.
>>
>> Since this part in the schematics is very hard to decipher here are my
>> questions:
>>
>> 1. Am I assuming correctly that for KLM-601 to work R159 has to be present?
>> Or is a wire jumper needed instead? I don't see how the Master tune would
>> otherwise be connected at all...
>> 2. Does the absence of R159 indicate that originally a KLM-601a was to be
>> placed here?
>> 3. Could KLM-601 be just omitted at all and instead R159 be used?