Open Music Labs Forums

Hello,
i managed to finish my xox-heart with pacemaker with everything working except the VCA out on my pacemaker board. As this is one many builds in the diy world i've done,i tried to troubleshoot as far as my electrons skill reached out. So i checked every connector, reflowed any suspicious solder point. VCO is fine and tuned to my taste, offset is as expected and VCF works like a charm (or better likely not). External signals will be processed too and CV and gate do their job as far as my module tester states. Only the VCA out is quit - no click, beep or hiss…flatline in the scope when i connect my probe to the VCA out jack.
Is there any point where i can start to check this out ? After two hours searching i'm kinda blind and confused…

Greets, nightworxx

sorry to hear its not working. here are a few things you can try:

1. do you hear the filter sweep with the gate signal?
2. apply an external signal to the VCF in and gate the xox-heart. do you hear anything from the vca out?
3. applay an accent gate, a vca gate, and turn accent full up. do you hear anything from the vca out?
4. do you have anything connected at J9? disconnect power, and measure the resistance between pins 1 and 2 on J9. should be a few kilohms.
5. make sure volume knob is full up, and probe for a signal on the volume knob (with gating).


since the VCF is fine, the vca is either not getting a gate properly, or the signal isnt making through the vca/mixer section. the volume knob is the output of the vca, and J7 is the output of the mixer. J9 is the audio input to the VCA, and r131 is a good place to look for the gate signal going into the vca.

Hi and thanks for your immediate help !

Finally i found the culprit. While performing your test procedure i was forced to plug/unplug the headphone/scope probe several times and it looks like it was a contact issue of the VCA out jack.
From one second to the other the signal appeared with the volume cranked up, so i nearly fell off the chair.
Nevertheless i replaced the wonky jack and will do further "testing".

Regards, nightworxx