Fender Red Knob "The Twin" All Kinds of Problems

[The Kabash]

Alright here we go (Breathe in...), I recently posted here about finding some replacement pots for some that were snapped off the amp. That was accomplished and I put them in, for the most part, I am still missing two 250K 20% push/pull (you know these...) Got Em? I'll Buy Em! But that is not why I am here today before you.

Folks we got problems, serious problems, and I am gonna need all of you to work together so we can get this thing solved.

Seriously though here we go.

Problem#1-
First, there was a serious buzz and a lack of power and any semblance of nice tone. So, I recently re-tubed the whole shebang. Bias/Balance etc. Power is back, and some would say decent tone yet that ridiculous buzz is still there. I can move the getfiddle around and it gets worse or it gets better but it doesnt last long in the better stage (I know I shouldnt have to move my guitar around to adjust the shitty sounds coming out of the amp). Tested two guitars does it with both, then I went to guitar center with the same guitars and they didnt buzz on there amps. SO what I am trying to say is that Amp buzz has nothing to do with guitar or pedals or cables. cool, cool.

Problem #2-
Verb aint working, used to work, dont work now. The buzz in problem #1 gets worse when the reverb knob is turned up.

Problem #3-
Channel selector aint working, used to work, dont work now (there seems to be a them here). I should say it works on other amps but not on the twin...anymore.

SIDE NOT (problem#3B)
I am having a hard time with this. Even though this footswitch did work I dont know if I have the selector that came with the amp. I have read a couple different thoughts on if a Double switch or a Triple switch came with the amp. I got this amp from its original owner and he gave me a double switch.

Ladies and Gents (lets just say that ladies means guitars). Thank you I appreciate all the help and I hope my humor is not lost or worse read as seriousness.

[g1]

Red knob "The Twin" used the 2 button footswitch, black knob "Twin-Amp" used the 3 button.
Does the ch.select pull switch on the amp work? If not, was that one of the pots that was replaced? Otherwise, check the diodes, LED's and jack in the footswitch itself.
Check the reverb tank cable connections and check inside the tank itself for broken springs or broken wires (the small ones that connect the tank jacks to the small transformers in the tank.
As far as the buzz goes, if moving the guitar around affects it, it may be some kind of interference at your location. Have you tried taking the amp somewhere else and trying it?

[Chuck H]

Also, if you still need two pots to complete some repairs, how is any evaluation possible at this time?

[Enzo]

Turn the volume control on the guitar to zero. Does the hum remain or leave? And is the hum present with NOTHING plugged into any input jack?

If it makes a difference which way your guitars are facing, then it may not be the amp's fault. The flourescent lights in a GC store are WAY over your head, but I bet in your basement or wherever at home, they are a lot closer. And at home there may be computers and other noisy things in the electrical environment.

[The Kabash]

The knobs are the ones that I cannot find a replacement for. Though the knobs are broken off I can still use them to change the volume. Although, I cannot use them as push/pull any longer. The reverb tank looks sound. The wires and connects appear normal but visual proof tends not to mean much in this case.

The footswitch is in perfect working condition. I have used it on other amps and it works gloriously.

[The Kabash]

Hum is present when nothing is plugged in but it gets worse when the guitar is plugged in & turned up.

[Chuck H]

Enzo was asking what happens WRT the hum when a guitar is plugged in and turned down to zero on the guitars volume control. He's checking for input jack faults.

[Enzo]

AACCHH, my secrets are out.

[The Kabash]

Yeah sorry guys. I checked and it goes away when the guitar is turned down. I say it goes away but there is a teeny tiny little buzz there but I do believe that is ok. what do you think? Also, what now?

[The Kabash]

I have also plugged into the other inputs (2 for channel switching mode and 2 for parallel channel mode) all will buzz. No fluorescent lights in the basement but quite a bit incandescent. also, there is wireless internet and many phones but that has always been and I have not had any buzz. I also installed a new 20 amp circuit to my bench that comes directly from the breaker (no junctions).

[The Kabash]

I referred to this thread for details about the reverb not working. I am up to the point of measuring the return to see if I have anything there. The springs do crash if moved so the return is working but I can't seem to get verb on the guitar. How exactly do I measure? Like down to which lines go where? I am a double novice.

[g1]

a) Disconnect the cable at the input of the reverb tank. Measure the AC voltage at the cable while you have signal running through the amp with reverb turned up. We know the return side of the reverb is working, so this will check the send side.
b) If turning the guitar volume off makes the amp quiet but it is noisy with nothing plugged in then there is some problem with the input jacks. There is a switch in the jack that is supposed to ground the input when nothing is plugged in. So with nothing plugged in it should sound the same as with the guitar plugged in with guitar volume at zero.
c) The fact that the amp is quiet with the guitar volume at zero implies that it is the guitar picking up the noise from the environment. You should try the amp somewhere else.
d)What is the condition of the channel select switch? It may be interfering with the footswitch.

[The Kabash]

Reverb is all figured out, wiring issue. I was thinking I should try the amp somewhere else, it will definitely happen now. Also, the footswitch has not been used during this time, since it doesnt really work I took it out of the equation. I had a 'duh' moment that Chuck H would say "he told me so." The channel select on the footswtich doesnt work because the channel selector knob on the amp in engaged and broken in that position. So unless I fix that knob I can't switch channels on floor. Although it does work for the reverb since that problem is sorted.

I will let you know after I take the amp to another enviroment

[The Kabash]

Alright guys, I too the amp to work and tried it there. The buzz/hum still exists, also occasionally I am getting strange sounds (like a synth...oscillations?) every once and awhile. What do I do?

[Jag]

Check the input jacks, especially the shorting connections to make sure it's working. It sounds like the inputs are open without anything plugged in. The shorting connection MUST come in contact with hot when there is no jack plugged in. Look for broken solders there too.