#1
For the past few days my amp as been getting worse and worse with this humming problem. I got a used Randall RG100ES a few weeks ago and it started out working fine with typical hum coming from it that didn't bother me. But as the time went on it started humming to the point where I can't even play at low volumes because I wont be able to hear the guitar. And on top of that now my clean channel is starting to have this gross, fizzy, overdrive that sounds like a tiny $20 amp being cranked all the way up and it's normally crystal clear even at high volumes.

Here's what I know:
-It's 60hz hum
-It's not my cables because I replaced them all and the problem is unaffected
-It's not the tubes because there aren't any
-The sound is not coming from anything on my pedal board because I can unplug the whole thing and it still hums a lot
-Its after the pre-amp in the circuit because the volume controls don't effect the volume of the hum
-It is not my cabinet because it hums no matter what I plug it into
-No variable has changed since the time it was working to now which tells me some part is going bad on the board or something
-The hum gets a little heavier when I plug my board into the effects loop
-Another problem exists where the volume will spike to much higher levels like a loose connection. That might just be the pots going bad, but the issue might be related to the hum, I don't know.

It's really starting to make me angry. I need some electrical knowledge help! My father is an electronics engineer and he went through with a schematic and an oscilloscope and still couldn't fix it. So I'm all out of ideas... I would take it to a professional but they're going to end up charging me more than the stupid thing is worth just to fix it.
Gear:
-Mesa Dual Rectifier (3 Channel) with KT88 and KT66 Tubes
-Peavey 6505+
-Roland JC120
-Ibanez Tone Blaster TBX150H
-Mesa 4x12 Straight Cab
-Marshall 1960BV
-Gibson Les Paul Custom
-Gibson Flying V
-Line 6 M13
#3
Like I said, nothing changed from the time I got the amp to now. I've been playing the same guitar. And no it would be impossible either way because the hum is after the preamp, meaning its not any pedal or guitar, its in the amp or the effects loop.
Gear:
-Mesa Dual Rectifier (3 Channel) with KT88 and KT66 Tubes
-Peavey 6505+
-Roland JC120
-Ibanez Tone Blaster TBX150H
-Mesa 4x12 Straight Cab
-Marshall 1960BV
-Gibson Les Paul Custom
-Gibson Flying V
-Line 6 M13
#5
Are you using a strat?
Agile AL3000
Douglas WRL90
SX SR1 STD Plus
J&D Strat
Squier Tele
Sammick TR2
Douglas Draco
Peavey JSX
Bugera V5
TWANGED VJ
#6
Just one question. Are you sure it's 60 Hz and not 120 Hz?
If it is definitely 60 Hz then the first place to start looking is a dodgey earth. Don't ask me why but it almost always ends up being a bad earth somewhere.
Gilchrist custom
Yamaha SBG500
Telecasters
Randall RM100 & RM20
Marshall JTM45 clone
Marshall JCM900 4102 (modded)
Marshall 18W clone
Fender 5F1 Champ clone
Atomic Amplifire
Marshall 1960A
Boss GT-100


Cathbard Amplification
My band
#8
*Bump*

I went through the whole amp and replaced all the 21 year old capacitors and it fixed the major hissing problem, but there is still a ton of ground hum. It doesn't make that big of a deal when I crank it, but I can't even practice with it. And its not just the gain channel, its the clean channel too.

If anyone knows anything about these amps, I have a few questions.

There is a trim pot on the inside on the bottom of the board about the size of a penny. What exactly does it do? Because I turned it and it fixed my hissing clean channel but it added EVEN more hum to the signal.

And is it normal, when I turn the gain all the way up on the lead channel, but the volume all the way down to get quite a bit of volume out of it? On any other amp this would be silent, on mine its at a practice volume when its all the way down. I think maybe my pots are going bad.

Any ideas?
Gear:
-Mesa Dual Rectifier (3 Channel) with KT88 and KT66 Tubes
-Peavey 6505+
-Roland JC120
-Ibanez Tone Blaster TBX150H
-Mesa 4x12 Straight Cab
-Marshall 1960BV
-Gibson Les Paul Custom
-Gibson Flying V
-Line 6 M13