Accented notes are just short pops!

[antto]

yes, as i expected, the problem is the filter envelope's decay time is far shorter than it should be
(the accent sweep circuit should be fine)
so check the resistor and capacitor there, and maybe also the decay pot (should be 1MegaOhm)

[r.odent]

Thank you for the advice! I will look into it soon. Is there a good way to figure out which of these components are busted without desoldering them? I'll start looking for shorts, anyway.

Thanks again! Could anyone record a sample demonstrating the lowest normal decay? Just out of curiosity.

[antto]

here: https://www.box.com/s/b10394c92835a3ab517f
this is a simple pattern of 4 "normal" and 4 "accented" notes running at 80BPM
decay knob is set to maximum all of the time

[r.odent]

I have now measured R138 and it is close to 68 KOhm over its terminals, and the traces from the pot and to R152 are fine. Shorting it out shortens the minimum decay time to nothing, as suspected, but now I'm at a loss as to how to find the source of the problem.

I'd rather not desolder anything, but I guess looking at the pot ought to be the next step. I really only have a very basic idea of electronics, so any help with how to take this further is appreciated.

[r.odent]

The rightmost two pins of VR6 (looking from the top of the main board) seem to be joined -- are they supposed to be? If not, can I just cut the rightmost pin as it doesn't seem to be connected anywhere else?

[MMM]

The rightmost two pins of VR6 (looking from the top of the main board) seem to be joined -- are they supposed to be? If not, can I just cut the rightmost pin as it doesn't seem to be connected anywhere else?

Please clarify - are you looking from the component side or the LED/switches side?

If it's the latter then it is the way it is supposed to be.

I'll look into your problem when time permits.

[r.odent]

Thanks, it's on the LED/button side, and looking at a photo of the PCB I found out what you just told me. The pot seems wired up correctly and there seem to be no bad joints.

[MMM]

So we need to have a look at the other suspects here.

Please check (visually) C62, measure R117, and measure if D26, D28 and D29 are ok.