[sdiy] Moog Source encoder issue

[Gordon JC Pearce]

On 12/09/12 21:33, Travis Thatcher wrote:
> My friend's Moog Source has a weird problem. It works fine (apart from
> 2 membrane buttons) for a while, but once it warms up the encoder
> doesn't respond as it should. It often just gets stuck going in one
> direction no mater which way you spin it. If i turn it off for like 5
> minutes it goes back to normal for a bit, then heats up and gets weird
> again.  I'm thinking a bad cap somewhere? Anyone experience this before?

I'd be really surprised if it was a capacitor.  The rotary encoder is 
(IIRC) an optical one like the quadrature wheel in a mouse.  If one 
"leg" is blocked, it will only count in one direction.  Check the DC 
conditions around the photodiodes and see if one of them is either 
biased too far on or off.

Do *not* start randomly replacing capacitors, that'll just make matters 
worse ;-)

-- 
Gordon JC Pearce MM0YEQ