Current Lover volume loss

[Derpinador]

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.

[thomasha]

Have you checked the voltage on both sides of r4?
It should be roughly at VB.

[Derpinador]

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.

[blackhatboojum]

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.

[Derpinador]

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....

[Derpinador]

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.

[Thewintersoldier]

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.

[Derpinador]

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.