Now I'm trying to find where my volume dies off on this 1, I'll get it out of the box if can't find the problem on the front side.
ic 1 ic2 ic7 IC 3
1: 4.7 9.08 4.54 9.01~3
2 4.7 4.47 4.55 4.48
3 2.34 4.04 4.54 4.35~48
4 0 1.1ma 0 4.28~49
5 4.14 0 4.13 4.38~50
6 4.56 ~4.36-47 4.55 4.24~48
7 4.40~1 ~4.01 4.55 4.5
8 9.08 ~4.0 9.09 0
9 4.26~48
10 4.3~5
12 4.29~49
13 0
14 4.24~49
15 4.29~49
16 0
ic 4 ic5 ic6
1 4.5 sweep 0
2 4.5 4.01~13 sweep
3 2.9~7.04 sweep sweep
4 0 8.98~9.01 0
5 4.35~50 0 9.08
6 0 0 9.08
7 0 7.71~76 sweep
8 0 sweep 9.08
9 0 sweep
10 0 sweep
11 0 0
12 0 4.08~12
13 0 4.06~4.22
14 9.06 sweep
Rough guessing that w/e is causing the low voltage at !C 1, pin 3 is the culprit. I admit I have no clue how to bleep bleep check a capacitor but the resisitors were in the 1% range, vishays or koa speers. pay no attention to the black on the trim pots, that was sharpie so my tired arse could tell where 50% was. the middle pin of the range pot IS filled in, that's just a shadow/dip in the solder pool.
Have you checked the voltage on both sides of r4?
It should be roughly at VB.
in relation to the IC above it, pin 1 side is 2.33 other side is 4.54. I'm using a 1 spot 9.4v 1700ma psu.
As thomasha pointed out, you should be getting roughly the same voltage on both sides of R4. The value of that resistor should be 1meg. I would check your solder joints on that resistor if you have the correct value in there.
value seems it is in range, 1012 when the DMM is on the 2000k setting, color matches, was yellow deficient lighting in the picture. good solder tents on the led/pot side of the board. I placed the probes from both sides of the board, same readings so it is a solid connection.
if it really comes down to it, I might snip out that trim pot, side says 503, I got a couple 10k and 250k's laying around....
I went back in with a new DMM, pin 3 is now at 4.55 where it should be but that resistor still reads 2.33 on the 3dpt side(visually) :-\
I'll try adding a pinch of solder from the topside to see if anything changes because that not achieving unity at the trimmer maxed is still bugging the living fark out of me.
In the spring of 2021 I built a current lover for someone else and ran into a low output level, even with the volume trimmer maxed out. I check all my values and voltages and everything was spot on. Upon audio probing everything was good going thru the front part of the circuit. I decided to trace the signal backwards and I found it dropped at a capacitor prior to the output volume. The cap measured half of its value. First time I've ever had a bad film cap. I replaced it and everything was A-1.
Well, I'll have to get an audio probe IF my JMK test rig never shows up, afraid I don't have something to check the cap out right now though. Ty for the advice Chris.