It looks like you have a stubborn amp it is probably alive and wants to participate in the rehearsals too

Alright. I talked to the guys at the repair place. Here's what was wrong with the amp, although I haven't received it back yet to test it and make sure it is cured. The amp tech said that I had a bad power tube. That was causing the P.A. to come through the amp. I'm assuming by bad, he meant bad microphonic. The weird crackle that we noticed when I took it in, that was caused by a "leaky capacitor." I'm not real sure what a leaky capacitor is, but he has the tubes and capacitor on order. Hopefully I'll get the amp back soon. When I do, I'll let you guys know if these fixes really fixed the amp.
Donnie.

Thanks Donnie. Be glad to know for sure.

If it does turn out to be the power tube then it won't be the first time one of my long and complicated suggestions turns out to be... wrong!

But one way or another we'll hopefully be able to remember what to tell the next guy that turns up with this unusual problem.

Good luck - C

I'm going to toss my $.02 worth in here so please only take it for what it's worth.

Many many years ago I had a similar problem with my old '73 Bandmaster. While it wasn't picking up the other instruments or the PA system, it was picking up local AM radio stations! The problem was very inconsistant...sometimes it would do it, sometimes it wouldn't. Sometimes it would be really loud and sometimes it would be barely noticeable. In fact I vividly remember one practice where I was playing Clapton's "Cocain" but I had Elvis Presley's "Love Me Tender" cranking out the speakers...it was really freaky to say the least.

I had many people suggest many problems including the microphonic tubes, but in my case it turned out to be the cable I was using! This was of course back in the day where I could barely afford new strings and I only owned two cables...the one from the guitar to my distortion and the one from the distortion to the amp but in any case, it never occured to me to check the cables themselves. Now here's the really odd thing...that cable never did that with any other amp...ONLY with my Bandmaster. I had used that cable on my Kustom, my Peavey and even my buddy's old Sunn and I never had a problem, but for whatever reason, I always got radio stations thru it with my Bandmaster. Also, I still have my old Bandmaster and she's never done that with any other cable or setup either (granted, I use much better quality cables now). I'm sure there must have been some logical explanation for it but I'd also be willing to bet that the physics book the explanation was in was probably on a back shelve in a library somewhere in the Twilight Zone, LOL!!!

Anyways, I know it's a long shot but if the tech doesn't come up with anything else, before you sink a lot of dough into repairs, check your cables.

Peace,
Jim

Hey, Ceri and Jim. Thanks for the replies. Jim, thanks for your input. I just bought some new Monster Cables, but I kept my old ones. So, I'll try it out with my old cables, too, when I get the amp back. Sometimes one little component can throw a rig off, and that's definitely something to consider. Thanks for everyone's input, and again, I'll keep you guys updated on the actual fix- if it actually fixes it. Donnie.

Hey, guys. I know it's been a while, but honestly I just got my amp back and was able to play it tonight. Guess what, it still happens. I was playing my 50's classic strat with custom shop '54 pickups and the P.A was still coming through like nobody's business. According to the repair guys, they replaced a bad capacitor and put in a new set of power tubes. Needless to say, I'm more than a little bummed. I tried turning the reverb to zero, to see if that was it, but no. I turned all the tone controls on the amp all the way down and that made the amp quieter, and so the P.A sound was quieter, but it was still there. I know the pickups in my Standard Tele are a bit microphonic, but do you think it's the pickups? If I tap on my Tele pickups, you can hear the tap coming through the amp, but not on my Strat with the custom shop pickups. You can beat on those all you want but nothing comes out unless you hit a string. I'm thoroughly bummed and am starting to think I should have held out for a Peavey classic 30.
Donnie.

Thats bad, I hate when stuff doesnt work the way it is supposed to.. its nerv racking to me h ah ah a anyway you can always sell your amp on ebay without losing much and then buy a different amp

Sorry it didn't get fixed the first time. Did you ever try changing your cords? Go straight into the amp without any stomp boxes/effects? I've posted in the past about my Cry-Baby wah picking up 96.1 FM here in Raleigh. I've never figured out why, plus it doesn't always happen. Grrrr.

Yep, tried new cables and tried going straight into the amp without any boxes. I talked to the guys at my local Fender shop and we're going to try a little experiment. I'm going block off the back of the amp with some cardboard or something to see if it is stage volume that it making the tubes vibrate and making the P.A come through the amp. If it affects the P.A volume even a little bit, then we'll know that we're on to something. If that works, it'll just be a matter of relocating my amp to a "quieter" part of the stage. Neither of us believe it is the pickups since they pass the "tap test" even with heavy gain. New tubes, so I doubt I got 2 bogus set of tubes from Fender. I also have access to a Fender Cyber Deluxe (solid state) and will see if the same problem happens with it with the same guitar and rig. It's a shame. The BJ sounds awesome, is light, has enough volume, and looks good. I just can't use it on stage right now. The sound guy at my Fender shop believes it is somehow related to the amp's position on the stage and position in relation to the monitors. We'll see. Thanks to all you guys for your input and advice. I truly appreciate it. Donnie.

When you do the board test if possible try lining it with silver foil to shield it. I noticed the other night my blues jr is very noisy with the back cover off. Maybe its some weird break in the amps shielding on that back cover. If you can fit some valve cans over the pre-amp valves that can bring noise down too. Let me know if you figure how to do that cos i cant suss it.

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Hi dalegribble: thanks for posting your continuing story on this amp.

When you told us the tech found a bad power tube I presumed that was the problem solved. However, since not, I'm reverting to my distantly remembered idea about the reverb. I shall go and have another search for that magazine article, but in the meantime I believe it may not have been merely to do with whether the reverb was turned up or not. I think it had to do with the physical position of the verb unit within the amplifier.

Since the tech hasn't solved your issue the job is not finished from his point of view. Take that amp back to him and talk about the reverb. Get him to entirely remove the short-tray spring reverb so's you can take the amp away and test it at stage volumes with the band. If the interference has gone then you know for sure where the difficulty lies.

As I said before, as far as I remember in the magazine article they tried fitting a new reverb, but that didn't sort it. In the end it had to do with the exact positioning of the verb within the amp. Weird, but there you go.

If your tech is authorised by Fender to do repair work under warranty then he should be able to consult Fender for backup on this. It won't be the first time the issue has occured. Also, with this ongoing fault it is perfectly reasonable for you to contact Fender's Customer Services department and ask for advice (email address elsewhere on this site).

The Blues Junior is one of the world's architypal amps: it needs to be made to work for you, not just replaced.

Cheers - C

Hey, Ceri. Yeah, I may have to resort to desperate measures to get it to work well. It's frustrating to have an amp sound as good as this amp sounds, but then have it butchered by the P.A feeding into it somehow. Last night, I remembered your suggestion and tried turning the reverb completely off, but that didn't help. Maybe I'll disconnect the tank and see if it helps tomorrow night during youth service.

Thanks also to the forum member for suggesting a foil backing for the cardboard. I had thought about this and you have convinced me to try it.

If relocating the amp or if foil/cardboard shielding it doesn't work, I'll get in touch with Fender Customer Service myself and keep taking it back until it's right. I don't know what else to do. Right now, the BJ is the perfect amp for me as it's light and easy on my bad back, sounds good, and has enough power for my needs. This is just one of those weird gremlin bugs to work out.

It baffles me though, that my co-guitarist's 100 watt Peavey Windsor (which sound wise doesn't do it for me at all) doesn't come through my amp, even though his half stack is practically right on top of my little BJ, but the P.A does. The weirdness continues. lol. I recently sold my Epiphone guitars, so I can't test them to see if the problem exists when using a humbucker guitar, but my co-guitarist has a Strat with a Dimarzio Tone-Zone in the bridge. I'll plug his guitar into my rig and test it out as well. Just to absolutely rule out the guitars. Donnie.

i had the same thing the pickups are so good you can here your self talkin in the background it was awsome

I got rid of my blues jr because of the reverb would go haywire every once in awhile. Its was my home practce amp so I wasn,t to upset now I have a Super Champ XD and love this little thing.

The reverb on my 95 blues jr does hum more depending on where its placed. Unfortunately fender seem to have it in the position of least hum. I think it comes down to too much crammed into too small a box. I ditched the speaker the other night and replaced it with a old carlsbro. The carlsbro is a lot deeper in size than the original eminence and the hum has increased. Theres two options, the first is to move the reverb tank outside of the amp. The second is to build a bigger cabinet. I wonder If Chet would chip in and tell us if any of this led him to build his beautiful cabinet for his Bjr.

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