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6 button on keypad intermittent

6 button on keypad intermittent

2016-06-04 by neil.macneil@...

Hey folks,

I'm new to the group, love it so far.  I've been modding my 800 mk1 with moog slayer, fm 800, etc.  A problem that I am seeing is with my 6 key on the keybed.  It intermittently works.  I'm reflowed solder over all the components and even replaced the 6 key button with a working one.  It seems if I keep pressing the 6 key and put my other hand over the bed of resistors on the edge of the board the 6 key starts to work again, sometimes for long periods.

Any clues as to what might be wrong, i'm pretty new to electronics repair.  I have a multimeter but not sure how to use it to check for bad traces or connections.  Any help would be awesome.

-Neil

Re: 6 button on keypad intermittent

2016-06-05 by neil.macneil@...

strange thing is if i push 6 with my other hand touch one of the connection under CN3 on the keypad board the 6 key works...

Re: [korgpolyex] Re: 6 button on keypad intermittent

2016-06-05 by Gordonjcp

On Sat, Jun 04, 2016 at 07:12:38PM -0700, neil.macneil@... [korgpolyex] wrote:
> strange thing is if i push 6 with my other hand touch one of the connection under CN3 on the keypad board the 6 key works...

And only 6, not any other keys in that row or column? If more than one key was affected I'd suspect the latch that drives the keyboard scanning. Since you've only got one key affected I'd be looking for cracks in the PCB.

--
Gordonjcp MM0YEQ

Re: [korgpolyex] Re: 6 button on keypad intermittent

2016-06-06 by Peter van Beerendonk

What about the simple solution, dead contact switch ?
 
----- Original Message -----
Sent: Sunday, June 05, 2016 10:53 AM
Subject: Re: [korgpolyex] Re: 6 button on keypad intermittent

 

On Sat, Jun 04, 2016 at 07:12:38PM -0700, neil.macneil@... [korgpolyex] wrote:
> strange thing is if i push 6 with my other hand touch one of the connection under CN3 on the keypad board the 6 key works...

And only 6, not any other keys in that row or column? If more than one key was affected I'd suspect the latch that drives the keyboard scanning. Since you've only got one key affected I'd be looking for cracks in the PCB.

--
Gordonjcp MM0YEQ

Re: [korgpolyex] Re: 6 button on keypad intermittent

2016-06-06 by James Brickman

I tried asking this before, but can anyone direct me tact switches with the right dimensions for the Poly 800 MKI?

On Mon, Jun 6, 2016 at 2:17 PM, 'Peter van Beerendonk' peter.van.beerendonk@... [korgpolyex] <korgpolyex@yahoogroups.com> wrote:
 

What about the simple solution, dead contact switch ?
 
----- Original Message -----
Sent: Sunday, June 05, 2016 10:53 AM
Subject: Re: [korgpolyex] Re: 6 button on keypad intermittent

 

On Sat, Jun 04, 2016 at 07:12:38PM -0700, neil.macneil@... [korgpolyex] wrote:
> strange thing is if i push 6 with my other hand touch one of the connection under CN3 on the keypad board the 6 key works...

And only 6, not any other keys in that row or column? If more than one key was affected I'd suspect the latch that drives the keyboard scanning. Since you've only got one key affected I'd be looking for cracks in the PCB.

--
Gordonjcp MM0YEQ


Re: [korgpolyex] Re: 6 button on keypad intermittent

2016-06-07 by Michael Hawkins

The correct approach is to thoroughly check everything and actually identify the root cause of the problem first. Then do what is necessary to fix the actual problem.

Trial and error repairs should be avoided at all costs when you're working with old equipment.

Especially since there are no switches to match the ones Korg used in the Poly.

It's not that hard to troubleshoot your particular problem. So be patient, exercise care, take your time, be sure of what you are doing and don't go replacing stuff willy-nilly.

/Mike


From: "James Brickman brickmaj@... [korgpolyex]" <korgpolyex@yahoogroups.com>
To: korgpolyex@yahoogroups.com
Sent: Monday, June 6, 2016 5:50 PM
Subject: Re: [korgpolyex] Re: 6 button on keypad intermittent

 
I tried asking this before, but can anyone direct me tact switches with the right dimensions for the Poly 800 MKI?

On Mon, Jun 6, 2016 at 2:17 PM, 'Peter van Beerendonk' peter.van.beerendonk@... [korgpolyex] <korgpolyex@yahoogroups.com> wrote:
 
What about the simple solution, dead contact switch ?
 
----- Original Message -----
Sent: Sunday, June 05, 2016 10:53 AM
Subject: Re: [korgpolyex] Re: 6 button on keypad intermittent

 
On Sat, Jun 04, 2016 at 07:12:38PM -0700, neil.macneil@... [korgpolyex] wrote:
> strange thing is if i push 6 with my other hand touch one of the connection under CN3 on the keypad board the 6 key works...

And only 6, not any other keys in that row or column? If more than one key was affected I'd suspect the latch that drives the keyboard scanning. Since you've only got one key affected I'd be looking for cracks in the PCB.

--
Gordonjcp MM0YEQ