Positive ground enclosure problem

[pokus]

Hey there,
got kind of a weird problem with my positive ground fuzz face based build.
It works fine when the in and out jacks are not fixed to the enclosure, but as soon as I give one of them a connection with the enclosure, the tone is completely gone. The input jack is a stereo one so that it connects the ring and the sleeve when it's plugged. The sleeve has connection to +9V (gnd) and the sleeve of the output jack. The ring to the board gnd.


Thanks for help!

[Fancy Lime]

Hi pokus,

i had that kind of problem many times. Unfortunately, there are a number of different possible causes. So here are some things I need to know to help you out:
Is this thing powered by battery or external power supply? If it is a power supply: is there something else (another effect) that is being powered by the same supply but has negative ground? Was this different between the tests with and without enclosure? If not: Is the enclosure somehow connected to the negative rail of the power supply via the power input jack or just by a chance short made by something touching the enclosure that shouldn't touch the enclosure?

Cheers,
Andy

[pokus]

Thanks for your answer. It's battery powered. I had also assumed that maybe something touches the enclosure, but couldn't find anything. Besides the power LED just works fine.

Noticed something that might help.
180kOhms between bat + clip and enclosure, 185kOhms between bat - clip and enclosure (when jacks not touching encl.)
0 Ohm between bat + clip and encl., 5kOhms between bat - clip and encl. (when jacks mounted)
Power ratings fit to that. 9V from + to -, 7.5V from encl. to bat- when not mounted, 9V when mounted.

So I guess there must be a touching connection somewhere. But I really don't get the 180 and 185kOhms measurements. 

[pokus]

Alright, I found the problem. Something was touching the metal cover of the 3pdt.

It doesn't really fit the topic, but has anyone found a good way to prevent a rotary switch from making those pop noises?
I assume I couldn't just add a pull-down resistor like at the input.

[mimmotronics]

It doesn't really fit the topic, but has anyone found a good way to prevent a rotary switch from making those pop noises?
I assume I couldn't just add a pull-down resistor like at the input.

It'd be wise to put this in another thread. For rotary switches, some simple high-pass filter could mitigate that. Cap in series with a resistor to ground after it, but the values need to be chosen so you're not sucking any tone out of the low-end. Someone else might have a better solution but that's what I would try first.

[intripped]

also a MBB (make before break) rotary switch type, could be a solution... depending on the application of course.