Forum upgrade to SMF 2.1.2, still working on re-theming.

Main Menu
Welcome to Solid State Guitar Amp Forum | DIY Guitar Amplifiers. Please login or sign up.

May 17, 2022, 04:32:58 PM

Login with username, password and session length

Recent Posts


Fender Stage 160 humming noise, please help!

Started by acalltoarms1087, December 05, 2011, 07:00:16 PM

Previous topic - Next topic


First post on this forum, so go easy on me!

I have a 2002 Fender Stage 160.

I'm having this awful humming noise coming from both of my speakers in this combo amp, and I haven't gotten to play in almost two weeks now. I'm desperate!

The story:
I was jamming out with my friend the other night, and out of nowhere, my amp started making a noise indicative of someone in the ICU. Of course I immediately shut it off and powered back up, still the same noise.

My take:
I'm an idiot.

I took a few steps already to attempt to narrow down the problem, and here they are:
1. unplugged EVERYTHING else in the room to rule out interference
2. unplugged my boss MetalZone pedal, to rule out 3rd party malfunction
3. used a different 1/4" cord, to rule out malfunction
4. unplugged the control pedal that was included with the amplifier to rule out malfunction
5. unplugged and re-plugged the two separate cords that connect each celestion g12t to the onboard processor

Also, there are a few things I have noticed that may narrow it further:
1. when the volume knob is turned, the humming neither increases or decreases in volume
2. changing channels (from clean to the onboard distortion) does not affect the sound whatsoever
3. the DSP effects onboard the unit do not change the sound at all
4. the external wiring in the speakers themselves seem to be okay (I played with them a little bit, no noticeable shorts or anything like that)

With a guitar plugged in, my input still plays, but the humming is there.

She is in my basement, where I have an industrial dehumidifier to eliminate moisture for too many guitars and 2 drum sets, so I think corrosion of metallic parts is not a possibility.

At the moment, I have the amp mostly taken apart (yes I know how it goes back together) and to be honest, I don't really have the slightest idea what to be looking for. I'm fairly confident that this has nothing to do with the input female or any of the onboard knobs or any other possible outside interference that I know so often messes with these fragile ticking time bombs.

Any help would be greatly appreciated!


Is it LOUD hum, everything else pretty much mute? If yes, it could be a blown power output. A light bulb limiter would instantly reveal if there's excessive current draw.


He reports that plugging the guitar into it he gets sound, so I tend to think it isn;t DC on the output.

My vote is the two main filter caps sticking up from the board.  WIggle them and see if the hum comes and goes.  In any event, I would resolder both of them and see if that helps.

In my experience, the most common repair I do to Fender solid state amps of that basic layout is to repair cracked solder to those caps.

I call it a "wedge chassis."  The chassis front panel is just tall enough for the row of controls, while the rear panel is pretty tall. so the shape of the chassis is like a wedge.    Probably no one else calls it that, but I do.   That configuration lets those caps shake around.


Enzo... not sure if you are still out there, but if you are, I just want to say THANK YOU!  I was having the exact same problem as the OP, loud buzz when power applied, regardless of the volume level. 

I've never worked on an amp before, but am electronically inclined. 

So long story short, after about 30 minutes of taking off the board from the chassis to get to the solder joints, I found one of the two big cap's solder joints was clearly visibly "cold" and loose from the solder trace.

I gave all four joints (two per cap) a re-solder and tested it out... No more buzz!  Just clean sound again.

So, once again, from the bottom of my heart... THANK YOU!! 


Welcome Squid86, and well done.

You have discovered a couple of things here, a) it often takes a lot more time to get an amp (or whatever) apart and back together than it does to fix the actual fault, and b) big components on PCB's often tend to do exactly this.  Solder is for electrical connection, not mechanical strength.

Caps in particular are often tied down with cable ties, or if there is no room, a big dob of glue.  If yours are not tied down or glued then I'd go back in and glue them down with a good bead of rubber cement or similar, but not epoxy or anything too "structural" - you may want to replace them some day.   ;)
If you say theory and practice don't agree you haven't applied enough theory.


I have the same problem but it blows a fuse if I don't run it through a voltage limiter? I replaced the filter caps and power transitors can anyone help me?


Hi resorb, welcome.

Yes - stop randomly replacing parts.  As you can see you have already spent time and money replacing parts and it hasn't got you anywhere.  Here we use diagnosis to first find out what is wrong, then fix that.  It's always quicker and cheaper in the long run.

Fed via a limiting lamp, what voltages do you measure on the +ve and -ve supplies, and on the output (disconnect the speaker)?  These should give us clues.

Schematic here (wait 30 secs for download prompt);
If you say theory and practice don't agree you haven't applied enough theory.


New here. I have a Fender Stage160 that was gently used when I bought it 8 years ago. I am a drummer and use it to play my IPad through for practice. Lately the amp crackles and loses volume after about 20 minutes and adjusting the controls does bring it back somewhat for brief periods. The only time it was used for anything else was with a Fender-Rhodes piano layout 7 months ago, and volume was high. Love the amp but don't want to spend a fortune to fix it. Any thoughts ??


Cleaning the pots and jacks is a good start and may clear up all your issues.
Beyond that, degradation of the solder connections is fairly common, on things like the main filter caps and power resistors.  Also at pots and jacks.
Without even opening the unit, try putting inserting a patch cord between the send and return (or pre-out, pwr amp in) jacks and see if that helps.