MB-6582 no audio!

MIDIbox SID
1

Got myself a “project” MB-6582 that someone never finished. Finally getting the build finished and all the build errors corrected.
Voltages are correct, and I managed to install the firmware. Leds, buttons, display work fine. Even managed to upload my old sammichSID patches. 

I am just not getting proper audio output. just a really really faint signal (or maybe it’s just the leds bleeding).

Tried it with a SwinSID and I can hear the SwinSID boot sound ok, but that either too does not make a sound after the bootup sound. Also tried different variations of connecting the feedback pots. Also ried swapping the 74HC595 chips, but no difference.

 

Any ideas?

2

if you have an oscilloscope, measure the audio-out before the Buffer-Transistors…

3

so you can hear the start up sound clearly and at full volume? That would suggest it’s not the ouput circuit I would think… hmm.