#1
Alright, so I just picked up my very first tube amplifier. I've been using a vintage solid state for years that did not include a built in distortion knob, which I have always made up for with a distortion pedal in my rig. That changed when I picked up my 5150 half stack; the tone this thing channels is insane! So the distortion pedal quickly went up on the shelf.

My only problem right now is that although the distortion pedal has freed up some space in the rig, running all my effects (phaser, flanger, booster, etc.) into the post overdrive/distortion in the amp head just doesn't work as effectively. Obviously that's why there's an effect's loop built into the back of the 5150; I have just never used one before and are quite lost, to be honest.

When I thought that I had set it up correctly by plugging in two standard instrument cables, like what you would use for the guitar, into the send and return plugs on the back of the head I didn't get a response from the amp.

There's the original footswitch which was included with the head when I purchased it with two buttons, which you use to switch between distortion/clean on the left button and turn off and on the effects loop with the right button. When I try pressing the right button there's no difference; the effects loop still doesn't work. There's a green light next to that button which I assume would light up upon pressing the button, but it never has.

I tested the effects loop by just turning on all the effects like the phaser and booster and flanger pedals, which should have made a dramatic difference in the tone, but nothing happened at all.

After inspecting the back of the head, on one of the two effects loop input jacks it's missing one of the locking nuts (assuming I'm describing this part correctly, it looks just like the nut on my guitar and those on the left and right of my pedals). Could this explain my problem? Might there be a related problem here?

Is there something I'm doing wrong as far as setting up an effects loop? I didn't actually have someone sit down and show me how to set up the effects loop so I'm rather lost. I appreciate whatever advice you can give.
#2
I have a different amp to yours but maybe I can help. There are a few things you can check:-

1. Check you are in the correct loop. I have 2 FX loops. One for the clean channel only and the other one for all 3 channels.
2. Check that the input setting is correct. I have a button for each loop which sets up the unput strength. One is for pedals and the other for racks.
3. Check that your pedals are connected properly. You might be thinking that you still get sound so they must be linked but you may have an FX mix (like mine). This controls how much of the FX mixes with the other signal. If your pedals aren't connected then you may only be hearing the main input.
4. Check you have the send to the first pedal and the return from the last one.

Another thing to note is that the prefered way seems to be to have distortion, fuzz and OD type pedals out front and time based pedals (delay, flanger, looper) in the loop.

I hope that helps.
#4
1. You should get that locking nut replaced. Probably not hard, should be able to find it at most music stores. IF they have a similar amp, show them, they are made in a couple of different sizes, or take another one off and bring it in to match it. Don't lose it...or pick up a couple of spares.

Spider is right, distortion type effects should be run in line, delay type effects through the effects loop.

How you plug things in matters.

Effects Send is the send, it goes into the input side of the first effect. Plug others same as you do for guitar when running in line, then plug the output from the last one into the Effects Return jack on the amp. Standard guitar cable should work fine.

Here's their user manual

http://assets.peavey.com/literature/manuals/80302108.pdf

I don't see anything in the manual about a signal level adjustment, if you know the effects work (try just one at a time to simplify things) it might need work.
Hmmm...I wonder what this button does...