Neurotron Ring Volume

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Hi folks, I've built a bunch of Aion boards and this is the first big head scratcher. I'm getting super low volume when it is set to Ring. I get full volume when it is set to octave, and though the volume is low everything else is functioning as it should. At 100% dry the blend pot is at unity volume and passes clean just fine, it just drops as you turn it clockwise. Has anyone come across this fun little gremlin?

NOTES:
1) Pulling IC2 makes it slightly louder
2) Pulling IC5 does not do anything, guessing the issue is somewhere in the wave former section?

If anyone has any voltages for their build that'd go a long way.

 

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Ok, I measured the voltages on the IC's.

IC1:
1: 4.51
2: 4.51
3: 4.5
4: 0
5: 3.68
6: 4.51
7: 4.50
8: 9.01

IC2:
1: 4.15
2: 4.15
3: 4.10
4: 0
5: 4.12
6: 4.14
7: 4.14
8: 8.27

IC3:
1: 4.14
2: 4.14
3: 4.14
4: 0
5: 4.13
6: 4.14
7: 4.15
8: 8.32

IC4:
1: 4.16
2: 4.16
3: 4.16
4: 0
5: 3.53
6: 4.16
7: .975
8: 8.32

IC5:
1: 5.97
2: 4.16
3: 4.16
4: 0
5: 5.49
6: 6.24
7: .833
8: 8.32

IC6:
1: 4.86
2: 4.14
3: 4.14
4: 0
5: 4.14
6: 4.14
7: 4.14
8: 8.29

So from this there are some irregular values in IC4B and IC5B, however IC4B is part of the LFO and that seems to be working so that might be a bad reading. I'll poke around IC5B this week.

 

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Double checked everything against the schematic and reflowed solder on every pad, still nothing. I've been futzing around with enough that the ribbon cables are starting to break so that's fun. Will be re-checking the wiring again, no doubt the issue is staring me in the eye but I'm too thick to see it.