Colossal Muffin Toggle Issue

[VanWhy]

I'm having an issue with the toggle switch so I'm looking to get some clarification on the schematic.

Toggle up and Toggle down work fine, center Toggle cuts the signal (aside from some very slight noise). I already tried another switch to eliminate that variable. I'm thinking it may be another component just not sure which.

It's tight to get a audio probe in there so I'm trying to find where to focus on. From what I see on the schematic, toggle 1 position is switching to C2 (100n) and toggle 3 position is switching to C3 (2u2 electro). And according to the PCB trace it looks like toggle 2 is going to R4 (470k). Am I right with that assessment? I swapped out R4 but that didn't help. I can start poking around but no positive where to focus. Any help is appreciated.

 

[owlexifry]

according to the PCB trace it looks like toggle 2 is going to R4 (470k)
View attachment 81269

to me it appears toggle pin 2 is going direct to base of Q1.
(R4 is a feedback/biasing resistor for Q1 that would affect all toggle modes).

i’m sure you’ve already done this, but i’d be probing (with toggle in centre position):
- both sides of C1
- base and collector of Q1
- confirm continuity between C1 and Q1 base

 

[cdwillis]

If you're not getting signal in the middle position it'll have to be the C1 cap. The little bit of noise is just some signal crosstalk from the other traces I'd guess.

 

[VanWhy]

If you're not getting signal in the middle position it'll have to be the C1 cap. The little bit of noise is just some signal crosstalk from the other traces I'd guess.

So I pulled C1 and it tested fine. Replaced it, and still nothing. I'm stumped.

I also checked and do have continuity from the middle position to the base of Q1. WTF

Edit: Q1 did test fine as well. It was socketed so I pulled the socket and went right in with the transistor to eliminate the possibility of a bad socket. Tested fine and even have continuity still fro. Base to center toggle pad.

 

[Feral Feline]

"So I pulled C1 and it tested fine. Replaced it and still nothing."

You've tested the C1 cap itself and the switch points to the Q1-base... seems you've test all possibilities except...

What I haven't seen, just to clarify, is whether you've tested the PCB at C1b (the switch-side of C1) and heck, for that matter C1a (R2 side...)
— as owlexifry and cdwillis have already mentioned, the problem would seem to be with the C1 location on the board, not the cap itself (for which you've already tested another cap).

Possibles:
Might be a dud board from the manufacturer.
Might be the board got compromised at C1 during initial soldering
Might be ... I have no idea what I'm talking about...



Regardless, post pics!

 

[VanWhy]

"So I pulled C1 and it tested fine. Replaced it and still nothing."

You've tested the C1 cap itself and the switch points to the Q1-base... seems you've test all possibilities except...

What I haven't seen, just to clarify, is whether you've tested the PCB at C1b (the switch-side of C1) and heck, for that matter C1a (R2 side...)
— as owlexifry and cdwillis have already mentioned, the problem would seem to be with the C1 location on the board, not the cap itself (for which you've already tested another cap).

Possibles:
Might be a dud board from the manufacturer.
Might be the board got compromised at C1 during initial soldering
Might be ... I have no idea what I'm talking about...



Regardless, post pics!

You know, I have not tested continuity from the C1 pad to the switch and the other side of C1 to R2. I think that's what you mean. I will do that tonight and see. Maybe I will post pics after that. I'm pretty turned off on the whole thing, but I will give it another shot.

 

[ODA]

You know, I have not tested continuity from the C1 pad to the switch and the other side of C1 to R2. I think that's what you mean. I will do that tonight and see. Maybe I will post pics after that. I'm pretty turned off on the whole thing, but I will give it another shot.

So? What happened?

 

[VanWhy]

So? What happened?

I never got it working. I just replaced the switch with an On/On and called it a day. Which sucks bc it's missing that middle "Off" position.

 

[andrewsrea]

With the toggle in the middle 'off' position, using a DMM check for continuity (1 Ohm 'beep') between the legs of C1 and the solder pin 2 of the switch. It should have continuity in all switch positions, including 'off'. Next check pin 2 to the base pin of Q1, with the 2nd pin of the switch. You can always solder a jumper wire from C1 to Q1.

 

[ODA]

With the toggle in the middle 'off' position, using a DMM check for continuity (1 Ohm 'beep') between the legs of C1 and the solder pin 2 of the switch. It should have continuity in all switch positions, including 'off'. Next check pin 2 to the base pin of Q1, with the 2nd pin of the switch. You can always solder a jumper wire from C1 to Q1.

With an on/off/on switch in the BASS, a jumper from C1 to Q1 sound like a possible fix (want to be sure you are on the correct side of the C1 cap and there is continuity between C1 & R2). C1 to Q1 should always be connected, does not matter if the switch is in the on or off position. The switch should be putting C2 or C3 in parallel with C1 for either of the (ON) positions on the switch, just C1 connected in circuit when switch is in the (OFF) position.

Jumping C1 to Q1 with the on/on switch will still work as well, just that C1 will never be in the circuit alone. Just my taste maybe, but I like the C1 (10n) cap by its lonesome here, less "muddy" with just the C1 in circuit without having to drop volume on the pedal.

 

[Feral Feline]

Meh... who even wants a puny piddly feeble pathetic little 10n as their input-cap anyway!

 

[andrewsrea]

Meh... who even wants a puny piddly feeble pathetic little 10n as their input-cap anyway!


If you are a bedroom player or solo artist, by all means - 'mo bass! If you are in a band and want to avoid volume wars, 10n helps.