Not a DIY pedal (yet) but have an issue with a Little Bear 3-in-1 Rat clone

[200hz]

This probably isn't the proper place to ask about this, but I'm pretty clueless on where else to go for good help.
 

So, I picked this pedal up 2nd hand for very cheap. The issue I'm having is it has a ground-type hum
when the footswitch is disengaged. It's not bad but gets louder/worse If I touch any metal/switch on the pedal. When
I turn the pedal on, it stops. It happens with no battery or DC power supplied to it as well, and actually if I take the
DC plug (pedal end) and just move it near the pedal it gets louder/worse. I've never had an issue like this with my
few DIY builds because of grounding or a bad joint, or any other pedal.
 

Any ideas what it could be? The unsoldered #6 lug on the footswitch caught my attention when I found another pic online that
showed the same, then saw the gutshot that is used on ebay for sales that had all 9 lugs soldered. I just thought it wasn't used
until then. Could that be it?


Here is a pic from mine.



Here is the other pic from Reverb



Here is the pic used to sale the pedal

[Travis]

The unsoldered lug on the footswitch shouldn’t need to be connected. That shouldn’t be an issue

It sounds and looks like they did not ground the enclosure. You could check for continuity between the enclosure and ground to see if it is connected

I must admit just looking at this thing is driving me crazy. Its like they bought the wrong parts and messed up their PCB layout and then just went ahead with production anyway

[200hz]

I'll give the continuity test a shot when i get a chance. Thanks for responding! I pulled the circuit out and scratched a bit around the 3PDT hole to see.
The inside paint job is definitely solid.

Yeah. As far as sound goes, it's actually pretty good for how cheap it is. Too much bass, perhaps, for me (I have a feeling when/if I bring it down
it's not going to sound as good). It also feels fairly solid compared to some Chinese cheapos. But much like you, I'm not a fan of the layout. It looks
like they were a bit stingy with the solder on quite a few joints. The Turbo mode is way louder than the other two modes. Trying to keep the distortion
down on the lowest cleanest levels actually keeps you from even being able to obtain unity gain on those two modes with the volume knob maxed.
It wants to howl and squeal with the volume knob up too much on at least one mode. It seems to pop the first time you turn the pedal on, but then
doesn't do it anymore. I'd guess that the LM308 Motorola is probably a knock off. I only played with it for a few minutes, so I'm sure there is at least
one more flaw in it somewhere.  

[200hz]

There was no continuity to the enclosure. It's there from the various points in the circuit that go to ground, pots, the 3pdt and negative off the supply/battery. With the pots I get a reading rather than a beep, at any setting. Just figured the resistance is still high. I took the paint to metal under one of the pots. The jacks are plastic enclosed/threads. I now have continuity between the pot casing/lug and enclosure, but still not from anywhere in the circuit to enclosure in either 3pdt position. The pot functions correctly. It seems to have alleviated the unity gain problem I mentioned. Still no continuity though. Weird

[200hz]

I guess I'll try jumping a wire from somewhere and put it between the pot and enclosure

[Travis]

It would be much better to have a dedicated ground lug mounted to the enclosure or solder to the back of one of the pots (assuming the pot is making good contact with bare metal of the enclosure)

[200hz]

Oh, for sure. I just meant for quick testing purposes.

[200hz]

That seemed to do the trick. Took the ground buzzes away, and a lot of the overall hum as well. It also seemed to put the volume differences on the two modes closer in line with the Turbo mode. I was at really low volume on the amp, so I'll have to see again on that part.

The open pad just to the left of the black (-) battery wire, above the jack, actually read constant to ground in all situations. So I just jumped with alligator clips from there to one of the screw holes in the enclosure. Had continuity in all the right places. I also clipped to the pot and all seemed good there too. I'll solder in on the pad, down to the back of said pot below.

I also noticed that a lot of the oscillation/squealing it's prone to with the volume pot seems to be due to some sensitivity to pickups in close proximity, for some reason. With single coils at least. When I turned the guitar away from it, it started behaving much better. I've seen enough talk and video of the pedal to know that this, the volume drops, and the ground issue are not isolated to just this pedal that I got, unfortunately.

Thanks for the responses even though it's not a DIY pedal. I'll get to start swapping a few things and spearminting once I get it to factory proper haha. I appreciate it

[200hz]

Well, it almost worked. It works and sounds like a rat pedal that has a proper ground now, but both clipping LED's stay on (if the mode toggle switch is on Turbo) when the pedal is switched off. It still passes the clean source as it should. If I turn the distortion pot down to a level that doesn't clip the LED's, then they stay off accordingly when I switch the pedal off.

Any ideas on this? I can't see how the pad I soldered from to the pot could have sent +9V to cause this if it's wired correctly, being that it's working correctly now aside from the clipping LED's. I didn't look at the trace on the bottom side of the little board though, so it's possible it's not a good spot to ground from. Is the board still getting +9V in the off position but not hitting the output, and could this be why it wasn't grounded to the enclosure??? Maybe I'm just better off cleaning the silicone off of the - battery wire joint and trying it there.

Just for fun, I'm sure you can see some of the flux and film that was left behind on the little board and 3PDT in the previous pics. Well, here is the solder side of the main board....

 

I gave them a good cleaning and tidied up a few joints after taking this picture. It made me feel a little better lol

[Travis]

I have built rats and other pedals with LED clipping before that behave that way. I’m not sure exactly what it is, but many high gain pedals will oscillate when you disconnect the input. My best guess is that the circuit is oscillating while in bypass which is providing the signal to light up the LEDs

I wouldn’t worry about it though. It shouldn’t affect the performance

[200hz]

Okay, thanks. It had me confused to the point of dumb thoughts trying to figure it out in my head, obviously.