Pro Junior problems - HELP!

[Dr. Lo]

I've got a PJ from the 1990s (bought it used off of eBay). It seems to need an amp doctor. Here are the symptoms:

1. When playing certain notes, particularly bassier notes, it violently snaps, crackles, and pops. This occurs with different guitars.

2. A couple of times, it just suddenly started to make this INCREDIBLY LOUD, unstoppable hum that did not change in intensity, irrespective of what I did with my guitar's controls (even with the volume off!). I'd have to turn off the amp and then turn in back on for the crazy noise to disappear.

What do you guys think the problem may be?

 

[marvar]

Re: Pro Junior problems - HELP!

tubes

 

[J Moose]

Re: Pro Junior problems - HELP!

I'll second the power tube suggestion.

Get a new set of EL84's in there and see if the problems go away!

If not, bring it to a tech ASAP!

 

[Curly]

Re: Pro Junior problems - HELP!

tubes can create a lot of symptoms, and are the easiest thing to replace

how old are the tubes?

 

[AdmiralB]

Re: Pro Junior problems - HELP!

Don't just plug-and-play power tubes. The PJ is fixed-bias, and has no provision for adjustment. It also runs the tubes fairly hot; if the replacement set runs hotter than the originals, you'll toast them.

 

[Dr. Lo]

Re: Pro Junior problems - HELP!

tubes can create a lot of symptoms, and are the easiest thing to replace

how old are the tubes?

The tubes are less than a month old. They are JJs.

 

[Curly]

Re: Pro Junior problems - HELP!

The tubes are less than a month old. They are JJs.

did you have these problems before you got new tubes?

it could be a microphonic or defective tube

you might be able to find the problem by tapping (very lightly) on the tubes with a pencil, one at a time, with the amp on, volume up

 

[Stratman]

Re: Pro Junior problems - HELP!

It could also be a resistor getting ready to burn out or a resistor that is operating (When hot) out of it's normal range causing the motor-boating bass sound that you are getting.

Have the amp checked real soon, it is normally a low-cost item to fix now a real expensive item to let keep burning out. (Think resistor verses transformer)

 

[WhoFan]

Re: Pro Junior problems - HELP!

i had some serious cracking and hum noises from my 65 Deluxe and it was some bad Capasitors. A low sounding hum would fade in and out and some cracking noises, output volume up and down.....

 

[Dr. Lo]

Re: Pro Junior problems - HELP!

The amp is with a tech now. I'll let you know what the actual problem was when I find out. Thanks for your help guys!