Grounding issue with rullywoa queen of bone (kot clone)

[Dirt_diggler]

I build a KOT clone today and it sounds absolutely beautiful..... only with Guts outside the enclosure.

I tried many different scenarios and have determined that the pedal is shorting out when the OUTPUT jack touches or is tightened into the enclosure. It also seems to affect the second side (left side) tone knob. I've reflowed both and even changed the jack to no avail. I can tighten down all of the pots and leave the output jack out of the enclosure and it works beautiful. It is strictly when the output jack is tightened into the enclosure. The backplate is never on and nothing is touching the jack lugs. it happens when the threads of the output jack touch the enclosure. Not sure where the grounding can be but what do you recommend?

Schematic can be found under the build doc pdf on this page.

Queen of Bone 2 (King of Tone™ 18v clone) PCB

Inspired by the King of Tone™ dual Marshall Bluesbreaker circuit – but with 18v charge pump onboard. Two overdrives in one pedal – great on their own or stacked. Uses standard 9VDC an…

rullywow.com

 

[Chas Grant]

Is the inside of the enclosure powder coated or painted, and if so did you remove the coating from around all the holes on the inside of the enclosure?
And something else to try, I had the same issue some time back on a simpler build, never found the reason for it but I removed the ground wire from the output jack and used the enclosure as the ground. The pedal is still working with no issues to this day. I got the idea from BOSS pedals, everyone I have ever opened has only a signal wire going to the output jack. Most likely to save a penny in cost on every pedal.

 

[Dirt_diggler]

Is the inside of the enclosure powder coated or painted, and if so did you remove the coating from around all the holes on the inside of the enclosure?
And something else to try, I had the same issue some time back on a simpler build, never found the reason for it but I removed the ground wire from the output jack and used the enclosure as the ground. The pedal is still working with no issues to this day. I got the idea from BOSS pedals, everyone I have ever opened has only a signal wire going to the output jack. Most likely to save a penny in cost on every pedal.

The enclosure is raw. As are the 6 other pedals I've built this month that have no grounding issues like this. Good idea on the output ground wire. I may remove that tomorrow and see if that does something different. Thank you.

 

[Dirt_diggler]

Im starting to feel like the output ground port on the pcb has something going on with it. I may jumper ground from the input Jack tonight and see if that could be the issue.

 

[zgrav]

do your LEDs still light up when the pedal is shorting out? (one way of seeing if the short is for power or just in the audio path)

does the pedal short out if it is in the enclosure but the pots are not tightened down?

you could have another part of your board touching the enclosure when it is mounted, so having your jacks contact the case shorts out the pedal. I don't see anything in the pics, but you may be able to spot something when looking at how it fits in the box and whether any parts are under stress when the pots are in place and tightened down.

the jacks should ground to the enclosure, so look for something on the board making contact when it should not be.

 

[Dirt_diggler]

Honestly I wasn't paying attention to the LED behavior so I will check that tonight. But I'm almost certain they do not light up when it's shorted.

I can tighten down the pots to the enclosure and still play it with the jacks outside the enclosure. When I let the output jack touch the enclosure, it shorts. I will say at this point when the output shorts the signal, if I touch the tone knob that's in the signal path to the output,the tone knob gives me crazy buzzing/him. Only when I touch or rotate. But still no signal because the output jack is touching the enclosure.

I can take the pcb out of the enclosure and play it but when I let the output jack touch the enclosure , it shorts out.

The input jack is not affected.

 

[zgrav]

see if you have continuity between the grounds on the input and output jacks. also when the output jack is installed in the case see if you have continuity between the audio terminal and ground. and then check the same jack again when it is not in the enclosure.

 

[Dirt_diggler]

see if you have continuity between the grounds on the input and output jacks. also when the output jack is installed in the case see if you have continuity between the audio terminal and ground. and then check the same jack again when it is not in the enclosure.

What do you mean audio terminal?

 

[zgrav]

What do you mean audio terminal?

the lug/terminal on the output jack that connects to the audio wire instead of the ground wire.

 

[Dirt_diggler]

the lug/terminal on the output jack that connects to the audio wire instead of the ground wire.

Ah ok. I thought that's what you meant. I know it by other names. Sorry about that.

 

[zgrav]

when the pcb is outside of your enclosure and working, you can also check to see if there is any voltage reading between the enclosure and the ground on the output jack. something happens when the case comes in contact with that jack, so the goal is to find out what it is and why it is happening.

 

[Chas Grant]

So I looked over the build doc and have a question. Does the pedal do this in bypass or when you engage a foot switch. And if only when foot switch engaged, one or the other or both?

 

[Dirt_diggler]

So I looked over the build doc and have a question. Does the pedal do this in bypass or when you engage a foot switch. And if only when foot switch engaged, one or the other or both?

Bypass works as it should and both sides of the pedal work if it's completely outside the enclosure.

When it's in the enclosure, no lights turn on. Again, the only time any problem persists is when the OUTPUT jack is touching the enclosure. When that happens. Nothing works. Not even LEDs

 

[music6000]

Try doing a Continuity test from threaded collar of each Potentiometer to Output Ground jack & Output jack lead while out of Enclosure.
Report back if & which pot is active.