Current Lover 2015 - Voltages off

[vegaobscura]

Spent some time putting this together -- get it powered up. Diodes turn on, that's a good sign -- so I went through to check the voltages on the ICs and immediately found some problems. IC1, IC6, and IC7 are all within expected values, but 2/3/4/5 all had some weird results.

IC2   Expected 8.8   9.13 0.23 4.45 2.3   4.85 0.63   41mv 0       0 8.8   4.45 0.4   4.2 0.4   4.2

IC3   Expected 8.8   9 0.1   4.5 8.8   4.5 8.8   4.5 0   4.53 0   4.5 8.8   4.5 0   0 0   4.5 8.8   4.5 0   4.5 8.8   4.5 ignore ignore 0   4.5 8.8   4.5 ignore ignore

IC4   Expected 0   4.53 8.8   4.53 0.05   varies 0   0 8.8   4.5 0   0 0   0 0   0 0   0 0   0 0   0 0   9 8.8   0 8.8   9

IC5   Expected 0.62   varies 8.8   4.2 5.5   varies 8.8   9 0   0 0   0 0   7.8 0   varies 0   varies 0   varies 0   0 8.5   4.2 1.2   4.2 7.5   varies

Checked the soldering on the sockets I used and they seem solid (it's definitely a messy job, but nothing THAT bad). Pictures here, in case something OBVIOUS stands out: https://imgur.com/a/hfYdzR9

Haven't checked audio through it yet, since the voltages were so off. Any thoughts or guidance would be helpful as I attempt to debug this one.

Edit: went through and reflowed all points. No change. Replaced the 680pf cap at C6. No change. Currently swapping out the socket on IC3.

[vegaobscura]

Things done so far:

Went through and reflowed all points. No change. Replaced the 680pf cap at C6. No change.
Swapped out the socket on IC3. Replaced IC3 -- saw IC3/4 jump to near-expected values. IC2 still off, however. I noticed that some values of the socket (without IC2 installed) are different and IC3/4 seem to drop a little 4.4 --> 3.9 in some cases) bolded below.

Re: IC2 pin 3, I have a voltage drop at C4 from 4.4 --> 2.21 across the capacitor. Bad cap?
Re: IC2 pin 4 - seems to have a load of 1.77+v with flanger switched, 0.6v with matrix switched.
No idea what's going on on IC2 pin 7/8 or with IC5.


IC2    Socket Values          Expected
8.8          8.8                     9.13
3.9         4.4                     4.45
2.34        2.4                      4.85
1.38v      drops to mv          41mv
0            0                          0
3.67      4.4                       4.45
0.56      8.67                     4.2
0.56      8.67                      4.2

IC3   Expected
8.8   9
4.41   4.5
4.39   4.5
4.39   4.5
4.41   4.53
4.39   4.5
4.40   4.5
0      0
4.39   4.5
4.41  4.5
4.39   4.5
4.4   4.5
ignore ignore
4.26   4.5
4.4  4.5
ignore ignore


IC4   Expected
4.29   4.53
4.29   4.53
5.15   varies
0      0
4.28   4.5
0      0
0      0
0      0
0      0
0      0
0      0
8.61   9
0      0
8.8   9

IC5   Expected
0.62   varies
8.8   4.2
5.5   varies
8.8   9
0      0
0      0
0   7.8
-    varies
-    varies
-    varies
0      0
8.67   4.2
.627   4.2
7.5   varies

[vegaobscura]

Questions I have for anyone with a working Current Lover:

What are the voltages you have across R22, R23, R42, and on the 3 pins of Q1? Trying to isolate where I may have a short or a bad trace.

Thanks in advance

[madbean]

For C4, you need to remember that this is a DC coupled cap. You are going to read different voltages on the two sides. For IC1 pin7 side you should read about Vb voltage. For the side going to pin3 IC2 it's going to depend on where the Bias trimmer is set. Speaking of which, you can jumper R10. This is something I need to address in the doc, 82k is a legacy value for higher voltage operation can be set lower or just subbed with a jumper.

Anyway, don't replace anything else. Try to find the source of the problem. The best way to do this is by removing ICs and looking at their voltages to track down the problem area in a linear way. So, remove all the ICs except for IC5. Now compare your voltages for IC5 to the ones in the doc. I'm saying start there b/c your voltages indicate that there is no LFO being produced, so that's the first problem to solve.

[vegaobscura]

I appreciate the help Mad -- that's basically what I've been trying to isolate and why I had asked about those resistors in particular. Picture attached is basically me trying to whittle down where voltages are weird.

IC5, no other ICs in the circuit:

1 .62       8 7.56
2 8.72     9  1.571
3 5.61     10 2.678
4 8.76     11 0
5 0          12 8.73
6 0          13 .625
7 -0.003  14 7.31

The voltage I have going into R22 (Vd) is 8.76v. Drops to 8.72v on the other side of the resistor. According to the circuit, that should be feeding to IC5 pin 2 -- which is supposed to be 4.2v. The resistor value (39k) reads correct in the circuit. Any thoughts on what might be going on there?

I'm not sure what's supposed to be feeding IC5 pin 7, since I'm getting such a different reading on that pin.