Fender Blues Jr 3 noise

[bsco]

Good day to everybody.....I have this amp here which did have an issue with the foot switch.....that is taken care of...however, the owner had mentioned that when the amp is just sitting there at idle, it will pick up some sort of interference in the form of a low level buzz...which sounds something like the buzz you would get if you put your finger on the tip of the guitar cable and have the volume turned down low.....seems as if it is picking up something that is switching on or off in the house...it does so in the owner's home as well......such as a deep freeze, fridge, etc.....you will hear a little click and then this low level buzz will be heard and then after a period of time will disappear.....could be gone for a while, then it will happen again.....and is totally random....Is this something that has been experienced by other people here?? and if so, Is there anything that can be done about it?? When you actually play the amp then of course you don't hear it...it is only when it is at idle with no input connected....any thoughts, comments, suggestions, etc welcome.....
Cheers

[Helmholtz]

Assuming the amp has shorting input jacks, it must be something on the mains voltage. I sometimes hear ripple control/mains signalling used by utilities for power managenent over here.

[bsco]

Assuming the amp has shorting input jacks, it must be something on the mains voltage. I sometimes hear ripple control/mains signalling used by utilities for power managenent over here.

Yes...the amp has shorting input jacks....if it didn't I would hear a small buzz all the time....I was thinking that noise on the mains is being picked up by the amp....and was wondering if there was something that can be done to solve the issue.......
Cheers

[Helmholtz]

Can you scope the mains voltage?

One cure could be to improve filtering by lower ESR/higher value filter caps.

Does it also happen with other amps?

[mozz]

Try shielding the ribbon cables. There was also a issue of one of the back screws being too long and touching the circuit. Search the BILLm website.

[bsco]

It has happened with other amps.....but I am not sure if it is only related to tube amps.....I just went to use the cordless phone and a buzz appeared in the speaker...very low level but it was there .....I am not sure what you mean by shielding the ribbon cables....wrap them in foil and ground one end to the chassis?? I was going to hook up an external AC outlet with it's own build it interference filter that is completely encased....These came from a casino gaming terminal...made by VLC or Hi-Tech or something like that...could have been from a Spielo Swinging Bells gaming terminal.....I have a bunch of these here somewhere...I will have to dig them out.....if anybody else has any suggestions I am all ears.....and I had the volume,gain and master volume controls turned all the way down just in case anybody was wondering....
Cheers

[mozz]

Does it at the owners residence and your's? Or is it just a problem with your power mains?

[bsco]

Does it at the owners residence and your's? Or is it just a problem with your power mains?

From what I understand, the owner also has the issue......and is totally random.....

[bsco]

Oh Shit.........I made a mistake....I said it was a Blues Jr. 3.......it is actually a Hot Rod Deluxe 3...I don't know why I had said a Blues Jr....I guess I should start a new thread and delete this one....

[Randall]

Is there a cell phone or computer nearby? I have been lead astray by both of those.

[bsco]

Is there a cell phone or computer nearby? I have been lead astray by both of those.

Actually Randall.....I have a cordless phone on my work bench and a laptop as well........the cell phone is upstairs......if I pick up the cordless phone and go to make a call,or, if somebody calls in, the amp produces the noise......if I hold it closer to the amp it will get louder and that is with all the controls turned down......so these electronic gadgets are producing interference which the amp is picking up..........and to be quite honest, I have noticed this with other amps....I can't say for certain if it also affects SS amps but it certainly does it with tube amps....and this is not the first time it has happened.....I will have to pay close attention to this to see what types of audio equipment it affects...Thanks for the reply....

[Enzo]

Tube, solid state, doesn't matter, any sensitive amplifier circuit can pick up interference.

My AT&T wireless desk phone sent all manner of noise into amps when I had it sitting right next to me at the bench. I had to move it away. Yes, cell phones often make clicks and pops as they check themselves in and out of the world. A sump pump in the basement used to send hash about the house to pick up.

I once had a baffling buzz that went for several seconds once a minute. It was only a stroke of luck that it was a warm day and I left it running to step out on the front step for fresh air, and I could hear this at the same time I noticed the traffic signal at the end of the block. The yellow light on one direction had a noisy triac in the circuit, so whenever that yellow was lit, noise went out on the power lines in the area.

My dad had a little fish tank heater, and it had a simple bimetal thermal switch inside to set the temperature. Every time it cycled on or off, the thermal switch contacts sparked, and I picked it up in my shop. Fish tank was on the other side of the wall of my shop in that house.

I had a CD player whose display send out digital noise to anything around it. I discovered that one day it was blinking 88:88 off and on, and the hash in my stereo exactly following along.


Noise could be coming in through the power line, but it could also be radiated. Plug the amp into a FILTERED power strip. Not just surge limited, but actual filtered. ANy change?

[Randall]

When I was a kid I learned that slowly flipping a light switch in the kitchen would make an audible buzz as the switch arced and would cause snow on the TV. That was my favorite trick for a while.

[mozz]

Just the other day i found out my Weller WESD51 soldering station was making noise and being picked up by a tonebender pedal i was working on.

[Enzo]

The little TO92 black plastic transistors, like 2N3904, may look opaque, but they are not. To IR light, they are little windows. Also LEDs and other diodes can be sensitive to light. SO when your chassis is out, fluorescent or other strobed light sources can bleed into circuits by shining through the walls of a transistor or into an LED.