Hi,
I built the Yocto v1.0 last year but got stumped when i couldn't get any sound out.
Symptoms are:
Sequencer runs normally.
The two trigger outs work fine as i can trigger external modules/kit
No MIDI out from the sequencer and no sounds triggered from the MIDI in.
So I thought i'd send a trigger to one of the internal sounds.
What i found was... patching Trigger 1 → R155 fires BD and all other voices.
Good news! Now I know most of the voices work (See below)...
so I'm guessing the fault is somewhere between ATmega MCU pins and the trigger in resistors.
I don't know the trigger resistors numbers for the sounds.
Voice-by-Voice Test Results
Working (when triggered externally)
BD — OK
Low Tom — OK
Mid Tom — OK
Rimshot / Clave — OK
Claps — OK
Cowbell — OK
Hi-Hat — OK
Not working / unusual behaviour
1. Accent – not working at all
Could a missing/broken accent path prevent internal triggers from firing?
(Accent is tied into several trigger conditioning circuits, so I am suspicious.)
2. Snare – not working
External trigger also does not fire it.
Maybe separate issue ... Could this be an op-amp issue? (It shares circuitry with noise source.)
3. Hi Tom / High Conga – extremely loud, no level control
Seems to ignore its VCA control path → maybe envelope or accent-related?
4. Cymbal – squealing tone; decay extremely subtle
Tone control seems to push it into oscillation. Unsure if this is normal Yocto behavior or a sign of a faulty filter/decay stage.
Is there any schematics available ? I can't find anything on the website anymore ... as this project is pretty old now.
Anyone out there that will know what I may have done wrong or where to go from here.
My thoughts are to find the schems of ATmega MCU and find the trigger outs and follow them. But this could be related to the Accent circuit not working?
Any help would be very much appreciated.
Regards
Rob