Muff - Only works in bypass.

[stodd420]

Hi,

I am building a Green Russian Muff from Musikding.

The led works and the pedal works in bypass.  There is no heat from the battery and I reflowed all the solder joints. 

When the switch is activated there is no sound.  Also when I move the tone pot there is a sweeping noise.  No noise from the other two pots.    Let me know if you need any further details.

Any help would be greatly appreciated.

Thanks

[Cozybuilder]

Please post clear detailed photos of your circuit, front and back, that will give us a lot more to go on. You referenced a schematic, posting it would be even better.

[stodd420]

Here are the links to the pedal details:

(Schematic and PCB)  http://diy.musikding.de/wp-content/uploads/2013/06/muffschalt.pdf
(Wiring Layout)         http://diy.musikding.de/wp-content/uploads/2013/06/muffwire.pdf
(Parts List)               http://diy.musikding.de/wp-content/uploads/2013/06/muffgreenbomenv2.pdf

Here is a dropbox link with some photos.  I can add more if needed.
https://www.dropbox.com/sh/2j1fp8wtnyjjg1l/AACN_9ITJ0Po2N_jfpOsYp2ca?dl=0

[Cozybuilder]

2 things I see immediately- some of the component leads are left a little longer than others when clipped, and the pots do not have "condoms" on them. Is it possible a pot is touching a component lead and shorting?

[stodd420]

I have left a fair amount of room between the pots and the pcb so I don't think that is the problem.  I will double check though.  I will also trim down the remaining leads. 

Thanks for your reply. 

[stodd420]

There is definitely no contact with the pots even when I push them down.  I checked it with a magnifying glass and there is no contact on the board anywhere that I can see. 

Any other suggestions?

Thanks

[Cozybuilder]

Double check the switch wiring- it kind of looks like you have the input jack and ckt input reversed.

[PBE6]

Use an audio probe or a scope to find out where the signal is dying. Once you've found that point, you'll be in a much better position to fix the problem.

EDIT: on second thought, Cozybuilder is probably right on the money, the switch wiring looks very strange.

[stodd420]

Thanks for your reply.

I followed the wiring on this link  -  http://diy.musikding.de/wp-content/uploads/2013/06/muffwire.pdf

I will try and get some better pictures.

[stodd420]

What is the ckt input you are referring to?

"it kind of looks like you have the input jack and ckt input reversed"

I will redo the switch wiring.

[stodd420]

I added a better close up picture of the footswitch in the dropbox folder.

https://www.dropbox.com/sh/2j1fp8wtnyjjg1l/AACN_9ITJ0Po2N_jfpOsYp2ca?dl=0

[Cozybuilder]

I just got through verifying R & C component values- the only 2 that were unclear were R6 ( 100R or 1K) and R22 (270R or 2K7), and neither of them would account for the problem. The solder joints look OK,  I assume you used 2N5088 trannys? If another tranny was used, check the pinout. If this doesn't turn up the problem, then do a voltage check- V+, and C, B, & E for each tranny.

[stodd420]

Yes they are 2N5088.  I have a multimeter here however I haven't really used it before.  Amateur.

Cheers for verifying those values.

[Cozybuilder]

I keep going back to the switch- that big blob on the Circuit In pin, with the black wire crossing over the output jack (center pin) bothers me. You don't need to ground the input when the pedal is in bypass, the 1M (R24) does that. Thus, I would remove that second wire, tidy it up some. The pot pin attachments should be reflowed, especially the volume. Use flux for that.

Multimeters are easy- get comfortable with it- measure some resistors first. Then switch it over to DC volts, with a range that goes above 9Volts (e.g. 0-20V). Place the black lead on any ground point, and place the red lead on the point you wish to measure the voltage of. Start with the battery connection at the power jack. Nothing? plug something into your input jack. Ok, now that its working, measure the individual legs of the transistors- E should be near 0V, B above that, maybe 2-3 V, and C around 4-7V. Let us know.

[R.G.]

Debugging thread: What to do when it doesn't work.

[stodd420]

Thanks this is very helpful.  Much appreciated.

[Mark Hammer]

Y'know, sometimes it happens that everything is wired up right, but during boxing up, what with flipping everything upside down, that the input jack ends up where you think the output jack is.  Bypass works in both directions, but the effect does not.  I'm not saying this has ever happened to ME (cough, cough), but it can happen.

[GGBB]

From the looks of that switch I'd worry that it has been overheated from soldering and has failed. Test for continuity between the circuit board and the jacks when the switch is in "on" mode.

[stodd420]

Thanks.  I have a few spare switches so I will try this out when I get a chance.

NOTE:  I removed the black wire going from top left to bottom right.  I also tidied up the soldering throughout the switch but there has been no change.  I shall replace the switch.

[Mark Hammer]

As always: