As Chrutil mentioned, we both have 2.4 boards. Here are a few of my learnings when debugging the boards:Nuclues wrote:Hi Whomper
Just to understand, is it vers 2,4 voiceboards you have in your working Fourvoice?
I have 8 voiceboards (vers 2,4) with no sound, so i'm very interested
best from Nick
1. Overall, following silkscreen you should get working boards.
2. Current schematics will allow you to (probably) debug most issues.
3. I missed R73 value as silkscreen is not clear enough, placing 6k4 instead of 46k4, which halved 2nd voice volume.
4. Replaced R202 and R204 with wires. Output volume was too low otherwise.
5. On carrier board, changed R2 and R3 too 4k7 and removed R34 and R158.
6. Removed all IC sockets on carrier boards (lifted a few traces alongside, nightmare...) as otherwise voice cards do not properly fit.
When debugging without the above changes, I got no output from carrier board, so figured voice board had issues, but when tracing signal with scope, I found out output volume was the main issue for me.
Recommend to start debugging one voice (per each voice card) at a time following op amp out pins with scope (in case you have) to make sure signal path is ok.
Also, make sure Xmute is off (this had me chasing fantoms at time), out volume pot is on max, envelop sustain on max and standard LP filter with no resonance in place.
You can also send me hi Rez pictures of your boards to compare.
I'ld like to thank Chrutil for his efforts helping me debug my board. I found one needs 50% debug tips and 50% mental support to finish the project :-)