"bitrex" wrote in message ...

On 05/01/2016 02:37 PM, wrote:
On Sunday, May 1, 2016 at 12:49:54 PM UTC-4, bitrex wrote:
On 05/01/2016 12:26 PM, wrote:
From your description, it is mechanical. Is there a way, using a
dental tool or similar that you might test each wire in the loom as it
goes into the connector? I expect you will find the problem there.

Peter Wieck
Melrose Park, PA

?

Press down on each separate wire as it goes into the MPC. A spade-type
dental tool is excellent for this purpose. The point being that if the
connector holds when under stress, but fails when there is no stress, it
is very most likely mechanical.

And, of course, it could be two-or-more things if you, in fact, bridged
something replacing a resistor.

Peter Wieck
Melrose Park, PA


Cool! The dental-spade trick seems to have found a candidate (I used a
tiny tiny phillips head screwdriver for manipulating each wire on the
header individually.)

Purple wire. When I wiggle that one around the keypad becomes
responsive. The others have no effect.

I did some reading and I think the reason the keyboard and the sound
engine is behaving goofy is because I swapped the RAM backup battery,
and it's become corrupted. The processor has no internal memory, and
uses the external battery-backed RAM for both its heap/stack and storing
patch data.

There's a startup key combination that instructs the processor to wipe
the memory and re-initialize, but of course I can't execute it when the
membrane buttons aren't working...: )






Here's what I put in my Service Report on an Alpha Juno 2 I repaired January
this year:

"Check Battery. Reinitialise RAM. Replace Power Supply capacitor.
Resolder all joints on Power Supply PCB. Clean all key contacts and contact
PCB"



The system here was corrupted, though the battery was good. You need to do
the reinitialise procedure.
And have a good look at the Power supply too.



Gareth.