Today, it is other channels that stay in tune, so that seems to change. I
have a manual, I assume the schematics are on the chroma webpage somewhere.
Maybe I'll be brave and try, but I don't have a scope. I also don't have a
desolder bulb thing, don't I need one? Thanks.

> From: Brinkmann Music
>
> I disabled channels 3,4 and 5. Then was able to play 3 notes
> at a time in tune. Sometimes I get a quick "portamento" when
> playing the bad channels- scoops up in pitch on first playing.

That sounds like problems in the sample-and-hold circuits. It's not a really
hard fix, but it does involve taking the board out (which disconnects the
battery and loses the memory), desoldering and replacing a bunch of parts.
I'd start with the pitch-related caps (Cx00, Cx01, Cx04, Cx05), then perhaps
the two 4051 switches (Zx01 and Zx02) on the affected channels. A scope
would make it easier to tell exactly what's bad, so you wouldn't have to
waste time changing things that aren't broken.

--

Ciao, Paul D. DeRocco
Paul mailto:pderocco@...