Cheap Pedal Only Works When On

Dave_Vader

Unusual problem, my recently purchased NUX Overdrive (chinese tubescreamer clone) decided that no sound was allowed through it if it wasn't on. Mid-gig, bit of a bugger, but just turned the drive down and got on with it, cleaning up by rolling back on the volume. Then replaced it on the board with another chinese Tubescreamer that isn't knackered (I bought this one so as not to keep swapping the other one from one board to another all the time).

Had a look inside but it's all PCB and no way of seeing how to try and fix it. I've got a partial refund from the seller, and will use the box to build something else, or keep it turned down as an always on bit of dirt for overclean amps.
It was only a tenner so I'm not all that bothered.
Just wondering if this has happened to anybody else?

57Deluxe

NuX and Kokko (same company) use different jacks. My German colleague investigated and reported:

The last "tongue" of the Jack is too small and it rests over the pit of the plug-tip, not over the top of the tip. See picture. The benefit of this is, that the plug sits very tight, but you can use only exact plugs.

http://i64.tinypic.com/xbesxw.jpg

With taller tips you just need to jiggle the tip out a bit and all is fine.

ICBM

If it works with the pedal on but not in bypass it's the switch. It can't be the jacks because then it wouldn't work if it was on!

If it's a typical 3PDT switch the chances are that the bypass is wired in the worst possible way for reliability, and you can fix it easily.

If it looks like this inside, it's that. (Not a TS clone but another NUX pedal.)

http://mirosol.kapsi.fi/wp-content/uploads/2013/10/Nux-AS4-2.jpg

Look at the switch wiring - at the lower right you will see two pins connected to each other. This is the bad bypass scheme because the signal passes through both switch contacts in series, and a fault in *either* will stop it working. To fix it, all you have to do is find which one has gone bad and jumper it to the next pin in the middle column.

Set up the pedal so you can play through it, with the bottom off. Set it to bypass (silent), strum a chord and short across one of the contacts with the tip of a screwdriver or something. If the sound comes back on, that's the bad one. Solder a short piece of plain wire across it.

Dave_Vader

Oh, thanks @ICBM  will give that a go later, was about to start using it as a paperweight.

ecc83

Slightly OT but on jacks... The standard pedal power regime using the TRS jack and the sleeve of a TS jack SHOULD work with a TRS plug if you wire ring to sleeve...But DON'T bet on it!

Tolerances can be so as to bite bum.

Dave.