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Subject: Re: [PolySix] Issue with patch Led's and Bank Led's after replacing buttons

From: Bob Grieb <bobgrieb@yahoo.com>
Date: 2015-01-16

A short to +5V on D0 would cause Bank A LED to be turned on
whenever IC2 on KLM371 is written to.   It would also cause Program
1 LED to be turned on whenever IC4 is written.  If you have a scope,
I would suggest looking at that data bus bit right at pin 2 of each of those
two chips, with the board in place.  If not, check resistance from that pin
to gnd, and also to the KLM-367 signal that drives it, with the board in
place.  Compare the resistance measurements from that signal to another
data bus pin.   D2, for instance.  Also, if D0 at those two chips is not
connected to the KLM367 driver, it is the same as if it's high (+5V).
That seems the most likely to me.

   Bob


From: "yanbu@comcast.net [PolySix]" <PolySix@yahoogroups.com>
To: PolySix@yahoogroups.com
Sent: Friday, January 16, 2015 4:05 PM
Subject: [PolySix] Issue with patch Led's and Bank Led's after replacing buttons

 
Hello, I just soldered on new buttons for patch select buttons 2 and 4, and the 'Poly' button since they were not responding on my Polysix. This was an easy enough task, once I placed the board back and re-attached it to the faceplate / front panel using the screws, there is a weird issue with the LED's. After turning it on it defaults to bank A and patch 1, however if I press the button for Bank D, both the Bank A and Bank D LED's stay lit. The same goes with the patch select buttons 1-8. 

What's weird is that when the entire board assembly with the metal cage that holds the individual PCB's together is not screwed to the faceplate / front panel, it works normally. But as soon as I touch the metal of the supports that hold the PCB's together to the metal of the front panel, the issue occurs. 

What on earth could this be? I checked my work and the solder joints are clean, nothing shorting out that I can see. The wires look fine as well. Has anyone run in to this before? Any tips on what to check for this kind of behavior? Really hoping to get some ideas, any help is appreciated.