Korg Mono/Poly group photo

Yahoo Groups archive

Korg Mono/Poly

Archive for korg_mono-poly.

Index last updated: 2026-03-30 01:09 UTC

Thread

New member... new problems... :)

New member... new problems... :)

2015-07-24 by jw_dewdney@yahoo.com

Hi everyone. I am new to the mono/poly world and am pretty excited by the instrument. I have been rebuiilding a few polysixes and an arp omni so i am a LITTLE bit familiar with the world of analog synthesizers. 


First question:

I was looking for a technical FAQ but was unable to find one. Does one exist for the group? I was looking for something that listed common problems and solutions.. though perhaps there are none here (can someone confirm?)


SECOND question:

The mono/poly i purchased was cosmetically very nice and the boards looked very clean - though the owner complained that only three of the keys worked- but for those three keys - apparently everything seemed to function very well. So I figured that it would just be an issue of cleaning up the key contacts.


When I received this unit - I could only get two keys to work - and shortly after that (as is the case now) only ONE single key is working - and there seems to be no audio output of any kind. I checked the power supply voltages and everything is FINE (!). So that's good. I"m wondering if there are obvious 'go to' failure points for such behaviour (?) - I checked voltages on the key assigner board per the service manual  but I wasn't sure about the specifics of shorting the 'tune point' (apparently lateratly between the jumpers?)


any suggestions before i get started?

Re: [korg_mono-poly] New member... new problems... :)

2015-07-24 by <alanmdicker@yahoo.co.uk>

Have you tested over ext CV control to see that the synth it working other than the keyboard?  The rubber contacts don’t hold up well to time and get less ands less conductive.  For mine rubbing them with a pencil eraser worked for a short while but ultimately they still stopped working.  I tried conductive paint but that soon flacked off and gave bad results.  In the end a Used a very sharp craft knife and sliced a thin layer of rubber from the black contact point and this brought the contact back to fully working order.
If the problem isn’t in the contacts them selves then check the CN connector is seated correctly or start probing the keyboard reader circuitry where the CV is generated.


Sent from Windows Mail

From: Alan Dicker alanmdicker@yahoo.co.uk [korg_mono-poly]
Sent: ‎Friday‎, ‎24‎ ‎July‎ ‎2015 ‎09‎:‎17
To: Alan Dicker alanmdicker@yahoo.co.uk [korg_mono-poly]

 

Hi everyone. I am new to the mono/poly world and am pretty excited by the instrument. I have been rebuiilding a few polysixes and an arp omni so i am a LITTLE bit familiar with the world of analog synthesizers. 


First question:

I was looking for a technical FAQ but was unable to find one. Does one exist for the group? I was looking for something that listed common problems and solutions.. though perhaps there are none here (can someone confirm?)


SECOND question:

The mono/poly i purchased was cosmetically very nice and the boards looked very clean - though the owner complained that only three of the keys worked- but for those three keys - apparently everything seemed to function very well. So I figured that it would just be an issue of cleaning up the key contacts.


When I received this unit - I could only get two keys to work - and shortly after that (as is the case now) only ONE single key is working - and there seems to be no audio output of any kind. I checked the power supply voltages and everything is FINE (!). So that's good. I"m wondering if there are obvious 'go to' failure points for such behaviour (?) - I checked voltages on the key assigner board per the service manual  but I wasn't sure about the specifics of shorting the 'tune point' (apparently lateratly between the jumpers?)


any suggestions before i get started?


Re: [korg_mono-poly] New member... new problems... :)

2015-07-24 by Florian Anwander

Hello and welcome!

Am 24.07.2015 um 10:17 schrieb jw_dewdney@yahoo.com [korg_mono-poly]:
> I have been rebuiilding a few polysixes and an arp omni so i am a
> LITTLE bit familiar with the world of analog synthesizers.
:-)

> I was looking for a technical FAQ but was unable to find one. Does one
> exist for the group?
There isn't one. But it would be a nice idea to start a thread, that
contains only postings that contain one question and its answer(s) per
posting. This thread should not contain any discussions.


In regards of your problem: Alan asked the right question already. The
key contacts are the most likely cause for the problem. You simply can
test it by shorting the matrix-contacts on the KLM356, connector 22 (you
may use a diode for it, but you don't have to).

You may check the VCO outs with a scope (the easiest points are the
waveform selectro switches). There should be atleast some low frequency
signal.

Next thing: check whether the switch contacts at the trigger-In socket
do give contact! Also the polarity switch might be corroded (in this
case the voice LEDs should be lit when you play, but you won't hear
anything nevertheless).

Florian

Re: New member... new problems... :)

2015-07-24 by Jonathan Dewdney

thank you for your suggestions. yes since I've previously fixed up the key contacts on my polysixes I'm pretty familiar with the procedure.. I just thought that since the lack of triggering was so complete, that maybe there was something else going on.

However, because of the sudden and total lack of audio output... I thought that was maybe a more pressing issue. Sorry if I wasn't clear enough about that in my post. So let's just pretend that this is the complaint. Are there any 'obvious' culprits to look at here?

Re: [korg_mono-poly] Re: New member... new problems... :)

2015-07-24 by <alanmdicker@yahoo.co.uk>

Thanks for the tip.  😊


Sent from Windows Mail

From: Alan Dicker alanmdicker@yahoo.co.uk [korg_mono-poly]
Sent: ‎Friday‎, ‎24‎ ‎July‎ ‎2015 ‎17‎:‎20
To: Alan Dicker alanmdicker@yahoo.co.uk [korg_mono-poly]

 

Regarding the keys not working, if it is the rubber contacts, you can try CaiKote 44, which is what I used...



Chip