As the LED's are driven by IC2 and IC3, I'd definitely suspect one of them. IC3 is just inverting the outputs from IC2 so I think you're going to be correct with IC2.
First of all I'd check that the solder connections for power to both chips are ok (14556 - pins 8/16 & 4011 - pins 7/14)
--- In Simmons_Drums@yahoogroups.com, jesper <jesper@...> wrote:
>
> philmurr skrev 2013-03-03 20:11:
> > I'm very happy my IV is working, next up is the SDS-V...
>
> Speaking of which...
>
> Can the tech guys here enlighten me regarding the program selector
> switches? I _guess_ the four switches end up at the same IC which opens
> the selected path... My hihat card works great upon startup if I stay
> with the factory preset. If I choose anything else it turns weird.
> Sometimes it plays some odd form of mix of all the presets but mostly
> it's just a lame and dull sound coming out. The LEDs either light up all
> or none. After fiften minutes or so it works as it should. It might be a
> bad soldering joint since heat might help...
>
> I dug out the schematics and looking at that crappy copy it looks as if
> the IC2 (14556) might be the culprit. IC1 is a 4013 btw. Any input from
> you soldering guys?
>
> --
> electronically yours, jesper
>
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> www.electronic-obsession.se
>