Zombie Chorus Not Working, Please Help

[Zumacalis]

This is my first time posting, so I'll try to be as thorough as possible according to the debugging thread.

1. It's a Zombie Chorus MN3207 version.
2. Here's a link to the schematic. https://docs.google.com/open?id=0B5yvyeA48lx2TnB6dzJGWENJdWs
3. I made my own perfboard layout, which I checked and rechecked. After putting it together I wish I would have just used a PCB.
4. I used TL072's instead of the TL062's and switched the pinouts to make the layout easier(1 for 7, 2 for 6, 3 for 5). This shouldn't matter though because each half of the op-amp is identical, right? I took out the trimpots and replaced them with a voltage divider like the one in this schematic https://docs.google.com/open?id=0B5yvyeA48lx2R25DUWlLV25jSVk. I also connected pin 4 of the MN3207 to the power supply instead VDD.
5. Negative ground, didn't change anything about that.
6. When the circuit is on, very little sound gets through unless I strum very hard, and then the signal "farts" loudly through the amp. There's also a quiet ticking, but I think that's because I used the same bias for both TL072's which I've read what causes the ticking.

I'm using a DC wall adapter, which is why the line voltage is at 9.48V

Voltages(with knobs at full, clone switch open) :
U1 (I switched the amps on the board, but I'll post them so they correspond to the schematic)
1 : Oscillates from about 3.5 V to 8.5 V
2 : 5V
3 : Oscillates between 4.85 V to 5.15 V
4 : 0V
5 : 5V
6 : 5.2V
7 : 5V
8 : 9.48V

U2 (again, pins 1, 2, and 3 are switched with 7, 6, and 5, on the board, but these are the voltages with reference to the schematic)
1 : 2.6V
2 : 3.39V
3 : 3.23V
4 : 0V
5 : 5.67V
6 : 5.75V
7 : 5.75V
8 : 9.48V

MN3207(The actual component I used is a VD3207D, but I've been told they are functionally identical)
1 : 0V
2 : 4.67V
3 : 2.6V
4 : 9.48V
5 : 9.48V
6 : 4.76V
7 : 5.8V
8 : 5.79V

CD4046
1 : 0V
2 : 4.67V
3 : 4.76V
4 : 4.76V
5 : 0V
6 : 1.15V
7 : 1.16V
8 : 0V
9 : 5V
10 : Swings from 3V to 4V
11 : Swings from 2.8V to 3.7V
12 : 7.7V
13 : 0V
14 : 9.48V
15 : 0.5V
16 : 9.48V

Thanks for your help.

[Scruffie]

If I understand correctly... your input opamp bias and BBD bias seem far too low, you should probably replace that V.Ref with a trimmer and try again, it would explain the farty sound.

[PRR]

> very little sound gets through unless I strum very hard

The dry signal only goes through U2A and then 10K to the output. So "NO" signal means problem here. "Fart" suggests U2A is mis-biased so that a strong signal moves it out of a dead-zone into a working-zone.

> U2
> 1 : 2.6V
> 2 : 3.39V
> 3 : 3.23V

All three pins should be at "Biass" voltage, noted as 5.2V. Why aren't they? Bad connection? Bad Biass voltage?

[Zumacalis]

Thanks for your inputs. I've been busy with other things so I haven't been able to troubleshoot this more. I'll try to get an update to guys tomorrow, thanks again for your help.

[Zumacalis]

I tried remelting the solder joints on U2 in case of a cold connection, no luck there.

I measured some voltages from the bias to U2A, and found something that might or might not be the problem. I measured the bias at about 5V, which should be fine for IC to work properly. Then I measured the voltage drops across the 1M resistor that goes from the bias to pin 3, and the drop across the 100K resistor, and found that both drops are about 1.5V, which would explain why the pins are at such low voltage.

I'll list all the voltage drops across the resistors connected to U2A for easier reference :

1M resistor from bias to pin 3 : 1.6V
100K resistor from bias to pin 2 : 1.7V
47K resistor from pin 2 to pin 1 : .8V

From my understanding of Ohms law, it seems like U2A is drawing too much current indicated by such large voltage drops.

I don't understand this circuit very well, so any further explanations of what's going on would be appreciated.
Once again, thanks for all your help.

[Scruffie]

I tried remelting the solder joints on U2 in case of a cold connection, no luck there.

I measured some voltages from the bias to U2A, and found something that might or might not be the problem. I measured the bias at about 5V, which should be fine for IC to work properly. Then I measured the voltage drops across the 1M resistor that goes from the bias to pin 3, and the drop across the 100K resistor, and found that both drops are about 1.5V, which would explain why the pins are at such low voltage.

I'll list all the voltage drops across the resistors connected to U2A for easier reference :

1M resistor from bias to pin 3 : 1.6V
100K resistor from bias to pin 2 : 1.7V
47K resistor from pin 2 to pin 1 : .8V

From my understanding of Ohms law, it seems like U2A is drawing too much current indicated by such large voltage drops.

I don't understand this circuit very well, so any further explanations of what's going on would be appreciated.
Once again, thanks for all your help.

Ah, that may be the impeadance of your DMM causing incorrect readings if 1M shows up as too low a voltage.

The other readings I can't look up to confirm what's going on right now.

[Zumacalis]

I have no idea what's going on with this thing now. I replaced the bias for U2A with a 10K trimpot, but when I lower the bias using the trimpot, the voltage on U2 increases. I get get clean output if I reduce the bias voltage to zero, which makes these voltages :

U1
1 = Flashes 0V, mixed with flashes of 1V - 9V
2 = 5V
3 = Flashes 0V, with 3V - 6V intermittently
4 = 0V
5 = 5V
6 = 4V
7 = 4V - 6V
8 = 9.5V

U2
pin 1 = 5V
pin 2 = 3.4V
pin 3 = 3.3V
pin 4 = 0v
pin 5 = 7V
pin 6 = 7V
pin 7 = 7V
pin 8 = 9.5V

MN3207
1 = 0V
2 = 4.7V
3 = 5V
4 = 9.5V
5 = 9.5V
6 = 4.75V
7 = 7V
8 = 7V

CD4046
1 = 0V
2 = 4.7V
3 = 4.76V
4 = 4.76V
5 = 0V
6 = 1.1V
7 = 1.1V
8 = 0V
9 = 5V
10 = 3.5V
11 = 3.5V
12 = 7.7V
13 = 0V
14 = 9.5V
15 = 1V
16 = 9.5V

I don't know if it was necessary to include all the voltages, but I wanted to be thorough.

An interesting thing happens when I change the bias when playing through the pedal. There's a point when the signal is heavily distorted, but there is a hint of chorus effect on it. Past that point, the signal totally cuts off, and enters into the "fart zone"

I hope this information is helpful for helping me out, because I would be shooting in the dark if not for your help.

[PRR]

> U2
> pin 1 = 5V
> pin 2 = 3.4V
> pin 3 = 3.3V

Is your 100K going to ground instead of to bias pot wiper?

[Zumacalis]

The 100k is connected to the wiper correctly, but I had forgotten to move the 1M resistor from the potential divider to the pot. Now that it's wired correctly, I'm getting the same voltages as my original post, and now I can't get any sound except farts with with the pot in any position.