Mini Me Chorus help

[Anonymous]

Hi, I bought the mini me chorus and I’m having trouble with it. I can hear the bypass but the LED won’t turn on and I can’t hear any chorus effect. It’s plugged into my MXR DC brick giving off 9.28V. My IC and transistor measurements are:

IC1

1. 8.62
2. 8.56
3. 7.69
4. 8.18
5. 7.59
6. 8.21
7. 8.62
8. 9.22

IC2

1. 8.6
2. 8.49
3. 6.11
4. 0
5. 0
6. 8.49
7. 8.48
8. 8.48

IC3

1. 8.37
2. 8.38
3. 8.21
4. 8.61
5. 8.61
6. 8.61
7. 8.67
8. 8.68
9. 8.68
10. 8.32
11. 8.35
12. 8.68
13. 8.32
14. 8.61

IC4

1. 8.24
2. 8.24
3. 9.06
4. 8.7
5. 8.24
6. 9
7. 9.25
8. 9.22

Q1

1. 5.58
2. (was not able to reach this one with my probe)
3. 0

Q2

1. 9.22
2. 8.22
3. 7.66

Q3

1. 8.61
2. 9.21
3. 9.22

[Anonymous]

Update: I have applied more solder to the 3PDT board and the LED is now working. I can hear clean guitar when LED is red, but when green I can only hear a hum that increases and decreases as I turn the trim pot.

[Billy]

Do you have ground going to the G2 pad can’t see it from your images

[Cybercow]

Close examination of the photo exposes several solder-starved joints. The solder need to flow thru to the opposite side of the board. I can’t help but wonder if a complete solder reflow is in order.

Also, for what it’s worth, I’ve built a number of Barry’s Mini-Me choruses now and since the new PCB allows the use of with the 3007 or 3207 – depending on the jumper settings beneath the BBD at IC2, I have always applied D4 instead of using a jumper. With D4 in place, either BBD chip can be used – just gotta pay attention to the jumpers beneath the chip.

And, the other ground point at ‘G2’ (in the upper left-hand corner) MUST be connected. (Can’t see it in the photos.) I connect mine directly to the DC jack ground.

Hopefully, addressing these points will help solve the problem.

[Anonymous]

I’ll add the ground wire and will try to reflow the joints. It will be tough to get to the ones underneath the pots however; I’m having trouble removing them.

[Anonymous]

I have now added the ground wire to the ground of the DC jack as you said, and have reflowed many of the solder joints. I now get a modulation sound, but it makes a high pitched squeaking noise if the rate knob isn’t maxed out or at zero. The depth knob also seems to not be doing anything. We’re getting somewhere now!

[Billy]

Try turning the trimmer in small increments to see if the noise improves and make sure power and ground wires cross over like this + and don’t run paralell like this =

If you haven’t already reflow the solder joints on the depth pot

It could be several things causing the noise and or oscillation

 

[Author]

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