Pro Jr. problem...

[jeffscreamedcorn]

I'm new here - this is my first post. I'm a novice, but maybe someone can help...

I recently got a great deal on a blonde Pro Jr. I bought it on a whim, and didn't check it out throughly - just enough to hear it work, and that it was a little tone monster. Today I finally had a chance to spend some time with it, and I observed that with the volume on zero (0), there was sound coming out. Not loud, but not a whisper either. Anyone have a clue what the problem is?

[Mars Amp Repair]

Well,
If you can get the sound to cut out completely at the lower end by wiggling it, it could be a dirty or bad pot (control). You can purchase some contact spray cleaner & spray a very small amount into the open slot next to the 3 contacts on the back of the pot, then turn the control up & down a bunch.

Note if you're new to amps, be certain to unplug before disassembling the amp. There are lethal voltages in there.
Also bad grounds on the low end of the pot could cause the issue, too. Don't know just how far you want to go with this or your level of experience.

glen

[jeffscreamedcorn]

Glen,

No amount of wiggling gives zero volume. The pots are not noisy at all, so I don't think it's a dirt problem. The amp is only about 6 moths old. I think the bad ground idea is worth exploring. I'll have my tech check it out.

I've been around amps for 35+ years as a player, but have only done basic maintenance - changing tubes, etc. I am interested in learning more about the inside of the amp. This summer I plan to try a simple amp build.

Thanks for the advice...

[Enzo]

Pots all turn down to the end of the resistive stripe inside. That SHOULD be more or less the end of it electrically so zero ohms to the end peg. But when made, not all pots go absolutely to zero. So some go not quite to zero.

Normally this is not a problem. If it is a little bit, ask yourself, is there ever a time I would need it to be lower than this? After all, if the guitar barely comes out, you generally only turn the control to zero when you want silence - which is when you stop playing - and nothing will come out when you set the guitar down. In other words, is this actually a problem for you? Or is it just something you feel should be otherwise, but is not really in your way? In the latter case, then , why bother?

If it is a matter of it only turns down a little but is still at playable volume, then we should at least check the pot for resistance at extreme settings.

[MWJB]

It's not unusual for Pro Jrs.

[Don Symes]

You can purchase some contact spray cleaner & spray a very small amount into the open slot next to the 3 contacts on the back of the pot, then turn the control up & down a bunch.
glen

NOT CONTACT CLEANER! - that will EAT the pot elements.
Use POT cleaner.