Mini Me – No output (solved)

[Anonymous]

Hey people, first time poster here. I just completed the Mini Me Chorus with poor results and I’m looking for some advice about what might be going on to get a diagnosis and fix set up.

What is going on: First time working with a 3PDT so I would guess my issue lies within the wiring, I couldn’t find any designated Mini Me photos for wiring with a 3PDT without a battery so I went of the generic diagrams I found and tried to figure it out. When I tested the completed pedal, the LED on the 3PDT lit up green/red properly when engaged or not engaged, but there was no bypass when not engaged and no output when engaged.

Thank you for looking and helping me out. I REALLY appreciate it.

Power info, below I will list my voltage reading. I used a 9v Boss adapter with the ground from the DC as the ground for testing. All ICs were in their sockets with double checked correct placement and direction:

IC1-This one is not too bad.
1. 4.6
2. 4.6
3. 3.4
4. 0
5. 4.5
6. 4.6
7. 4.7
8. 9.2
IC2-Getting kind of off.
1. 7.8
2. 8.2
3. 5.5
4. 0
5. 0
6. 8.3
7. 7.4
8. 7.4
IC3-Not even close.
1. 8.3
2. 8.2
3. 8.2
4. 8.6
5. 8.6
6. 8.6
7. 8.5
8. 8.5
9. 8.5
10. 8.3
11. 8.3
12. 8.5
13. 8.1
14. 8.6
IC4-Not even close.
1. 8.6
2. 8.6
3. 8.7
4. 9.2
5. 8.7
6. 8.6
7. 8.7
8. 8.7
Q1-Alright.
E. 5.1
B. 3.4
C. 0
Q2-Pretty off.
E. 7
B. 6.8
C. 9.2
Q3-Alright.
E. 8.6
B. 8.6
C. 9.1

[Billy]

You also need to wire G2 top left to ground can’t see if there’s a wire there, it doesn’t look like there is and IC4 looks to be the wrong way around dot needs to go to bottom right so just flip it around, that will be why your voltages are so high for IC4 no ground connection to pin 4

[Anonymous]

IC4 was backwards (corrected now), I reversed the output wires, and G2 is not grounded to anything. Where would I ground that since my input only has the ring and tip lugs and I used the 3PDT?

Thanks for the help fellas, more eyes make less mistakes.

[Billy]

I’d just run another ground from the DC jack, a nice short wire

All I’d do is melt the solder and stick another wire in the DC jack ground lug then over to G2 just tin both ends of your wire and you can do it on the topside of the board save you removing it from the enclosure, you could actually just tack both ends on if you tin both ends it’ll just be a case of holding the wire on and melting the solder in place

It’s a beautiful sounding analog chorus you’ll love it I always keep going back to it and ditch the all singing all dancing choruses

[Barry]

This is the manual for our 3PDT Wiring Board found on our Guides Page.

https://guitarpcb.com/wp-content/uploads/2020/06/BD_3PDT-WIRING-BOARD.pdf

[Anonymous]

I’ve tried to fill the G2 hole so many times that it’s filled with solder which I can’t suck out and I can no longer thread the tinned wire through. It’s frustrating to say the absolute least.

[Billy]

You dont need to put it through the hole, ideally yes, but just tin the wire end place it on the G2 pad and melt the solder together for around 3 seconds, remove the IC from it’s socket and just take care and take your time if you put enough solder on the wire with the solder already on the pad it should be fairly easy, unscrew your pots so that you can raise the pcb up a little

If you look at this picture you’ll see I’ve simply tacked the resistor onto the +V pad all I did was tin the resistor with solder hold it on to the +V pad and melt it

[Anonymous]

OK I surpassed that evil hole and got the thing “working” as in it is functioning during output but it doesn’t really sound like much is happening to the signal at all. It’s hardly noticeable at all when engaged and both Depth and Rate are dimed, doesn’t sound anything like the demos online. When I plug it in and it’s not engaged the bypass works, click on normally and the controls don’t seem to work and the tone is maybe a little fuller than normal, click off and it makes a loud pop noise and will make a clicking noise like a stun gun.

Here are my current voltages, some of them are somehow more off than yesterday (?) and I am not sure what’s going on there but I did implemented all of the suggestions you all made and it did improve but it’s still not right yet. I am open to any and all help. Thank you for your time and dealing with my frustration and being a novice. I can post any additional pictures as well.

IC1-Way off
1. 8.8
2. 8.8
3. 0
4. 0
5. 9.1
6. 8.8
7. 8.8
8. 9.4
IC2-Not very close.
1. 8.2
2. 4.3
3. 8.3
4. 0
5. 7.8
6. 4.3
7. 7.8
8. 7.8
IC3-Pretty good.
1. 8.6
2. .02
3. 7.4
4. 8.4
5. 8.7
6. 8.7
7. 0
8. 0
9. 0
10. 4.3
11. 4.3
12. 0
13. 8.6
14. 8.7
IC4-Pretty good.
1. 1.8
2. 4.3
3. 4
4. 0
5. 2.3
6. 2.2
7. 4
8. 9.4
Q1-Way off
E. 8.2
B. 9
C. 9.2
Q2-Way off
E. 9.2
B. 9.1
C. 9.3
Q3-Okay?
E. 8.7
B. 9.3
C. 9.4

 

[Billy]

I can see why G2 was such a pain I meant to do it on the topside of the pcb

There is a chance you could have fried something by inserting IC4 in the wrong way around and powering the circuit

You don’t have VB on IC1 all pins should be around half your power supply except pins 4 ground and 8 power check what voltage you get on the junction of R32 and 33 the voltage divider

[Billy]

Those voltages are fine I’m having to go out at the moment in the meantime

looking at the old build doc it looks like you need to place a jumper in D4 pads

Check what voltages you get on IC1 empty socket

IC4 voltages as you say look ok, the voltages on pins 1,5 and 7 should fluctuate.

[Anonymous]

A jumper that only goes between the two holes of D4?

IC4 Fluctuations:
Both settings at 0:
1. 1-3, constantly moving
5. 1.5-3.5, constantly moving
7. .02-8, constantly moving
Both settings at 10:
1. 1.76-1.85, constantly moving
5. 2.22-2.35, constantly moving
7. 3.95-4.45, constantly moving

IC1 Socket:
1. 3.63
2. 3.54
3. 3.75
4. .01
5. 4.55
6. 3.66
7. 3.56
8. 9.33

[Billy]

Yes that’s correct either a jumper or diode

I’m assuming you haven’t adjusted TR1 set that to the centre position, I’d put the jumper or diode in D4 then recheck voltages

I haven’t built the 2020 version but as I say looking at the old build doc pins 5 and 4 on IC2 are connected in the schematic

Have a look at the build notes again there are notes in the doc regarding G2, TR1 etc

You will now at least have to unscrew the 3PDT, jacks and pots and try tilting the pcb outwards to access the D4 pads you would need to desolder the wires from the DC jack if you’re going to completely remove it from the enclosure

 

 

[Anonymous]

Jumper for D4 is in place. G2 is grounded to DC ground per forum advice. GND on the PCB has two holes so I grounded the white hole to the top left G hold on the 3PDT, and grounded the top right 3PDT G hole also to the DC ground (as shown to do in the diagram and per forum advice).

I plugged it in and tested and here’s how it functions now. While receiving power and not engaged there is no sound, when engaged there is output but it just sounds like my clean tone and the Depth/Rate do not affect the sound. I adjusted TR1 with 45 degree turns in both directions and 90 degree turns in both directions with no change in sound. When I disengage there is a loud pop, no guitar output sound, and the stun gun sounding clicks are present.

[Anonymous]

What component voltages should I check and how should I have TR1 set to check them? It is currently set back to this.

[Billy]

That looks to be halfway

Recheck all of your voltages

IC1 particularly

I’m assuming you’ve used this to check voltages

Hopefully your voltages will be closer with the changes you’ve made its just a case of trying to make sure the ICs etc are ok

IC1 out of socket looks much closer you check your VB pins with no IC in the socket to check you’re getting VB and ground where expected on the schematic e.g. IC1 pins 3 and 5 if you look at the bottom right power section you’ll see pins 4 ground and 8 power if you get high readings for the IC pins it either indicates the IC is faulty or there’s a cold solder joint on the socket or short somewhere using the schematic you can see VB points to check where you should get 9v and so on

[Cybercow]

Thor – “What component voltages should I check and how should I have TR1 set to check them? It is currently set back to this.”

TR1 is used to find the “sweet-spot” to obtain the correct clock rate and get the BBD to do it’s job. The setting of TR1 should have no affect when checking the voltages. (See the notes.)

And mind you please, adjusting TR1 to find the chorusing “sweet-spot” is rather tricky affair. Use very tiny changes as the “sweet-spot” is a very narrow range within the trimpots sweep. Good luck!

[Anonymous]

Alright so after I get these other issues dealt with I will continue to test the TR1. The notes say the sweet spot should be slighty to the left (so if I leave it in the current position and turn it slightly to the left I could hear results?).

All of the IC voltage measurements are from the sockets only (I don’t know what any of the measurements mean for next steps), however I left the transistors in their sockets (Q1&Q2 seem very off). I can pics of the underside of the PCB for you to see if there are any cold solders, though there shouldn’t be because I was extremely diligent about not having cold solders or bridges. Thank you guys for the help too, I hope with your experience knowledge we can get this running.
IC1-
1. 7.42
2. 7.21
3. 7.26
4. 9.25
5. 9.15
6. 7.42
7. 7.24
8. 9.46
IC2-
1. 0
2. 0
3. 8.55
4. 0
5. 0
6. 0
7. 0
8. 0
IC3-
1. 0
2. -.01
3. 0
4. 8.94
5. 8.94
6. 8.93
7. 0
8. 0
9. 0
10. 0
11. 0
12. 0
13. 0
14. 9.3
IC4-
1. 0
2. 0
3. 4
4. 0
5. 0
6. 2.23
7. 0
8. 9.45
Q1-
E. 9.45
B. 9
C. 9.3
Q2-
E. 9.25
B. 0
C. 9.45
Q3-
E. 9.46
B. 9.36
C. 8.94

[Author]

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