Apparent Voltage Converter Issue

[drchek]

I'm debugging my build of this famous pedal (schematics linked) and it seems there is an issue in the power section of the circuit with the ICL7660S.

Here are my voltages on the ICs (from bottom to top):



IC3 (ICL7660S)
1  9.3
2  4.5
3  0
4  -3.5
5  -6.6
6  5.0
7  4.4
8  9.3

IC2 (TL072CP)
1  4.7
2  4.7
3  4.6
4  -6.7
5  4.6
6  5.5
7  6.6
8  7.9

IC1 (TL072CP)
1  4.8
2  4.6
3  1.5
4  0
5  4.1
6  4.7
7  5.0
8  9.3

From those numbers it looks like two of the voltages from the voltage inverter/doubler section of the circuit are out of whack: -V: -6.7V (expecting -9V) and +V2 7.9V (expecting 18V).

Any ideas?

[Groovenut]

Here are known good voltages

Measurements taken with a regulated bench supply set at 9 volts using a Fluke model 87V meter with fresh calibration

IC1 - TL072

1 = 4.49
2 = 4.49
3 = 3.54 stable, 3.95 initial
4 = 0
5 = 4.49
6 = 4.49
7 = 4.49
8 = 9


IC2 - TL072

1 = 4.55
2 = 4.49
3 = 4.49
4 = -8.59
5 = 4.49
6 = 4.49
7 = 4.44
8 = 16.23

IC3 - ICL7660SCPA or TC1044SCPA

1 = 9
2 = 4.59
3 = 0
4 = -4.22
5 = -8.59
6 = 4.09
7 = 5.59
8 = 9

At a guess, have a look for an issue around pin 4. Cap orientation, gounding etc. It should measure ~ -4V. Replace the charge pump with a new one to see if thats the issue, also check the rectifier connections.

[drchek]

At a guess, have a look for an issue around pin 4. Cap orientation, gounding etc. It should measure ~ -4V. Replace the charge pump with a new one to see if thats the issue, also check the rectifier connections.

My oversight. That reading for pin 4 is negative. I've updated the original post to reflect that.

I'll go through and check the surrounding components to see if I can find anything.

[drchek]

I fixed a couple of sketchy solder joints and have gotten almost all the voltages to fall in line:

1=4.8
2=4.8
3=1.3*
4=0
5=4.7
6=4.8
7=9.2*
8=9.3

IC2            
1=4.9
2=4.8
3=4.7
4=-9
5=4.7
6=4.8
7=4.6
8=17

IC3            
1=9.3
2=4.6
3=0
4=-4.5
5=-9
6=5
7=4.5
8=9.3

The * indicates pins that I'm still concerned about...