I recently picked up my first real amp head and haven't been able to use the effects loop yet because it just doesn't work. I apologize if that seems vague, but I literally can't manage to make it work.

I used to run my pedals into a solid state combo amp and would place a distortion pedal in the mix before my delay, flanger, harmonizer, etc., but since picking up my new amp head I've been in love with the distortion/overdrive it produces and have set the distortion pedal on the shelf for the time being.

That being said, flanger and like minded effects don't sound nearly as good when they're run straight into the main input and then overdriven and distorted by the amp head. Here's what I've tried doing:

1. running the cable from my guitar into the wah, tuner, overdrive pedals and sending that signal into the main input of the amp head

2. running a cable from the effects send on the back of the amp into the flanger, delay, harmonizer and eq pedals on the pedalboard, then back into the effects return

Am I doing something wrong? Because when I set up my rig this way, I don't hear the harmonizer, delay or flanger pedals at all. Please let me know what I can do to make the effects loop cooperate here.
What amp?
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
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Peavey ReValver Amp Sims
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Yeah, what amp? I would guess there's a bypass switch, an effects loop volume that is turned down, or if its a tube power FX loop the tube could be dead.
I don't give a shit if you listen to me or not
Hey all,

It's a first gen Peavey 5150 head with the big block letters on the front. It came with a footswitch that controls both clean/overdrive on the left button and the effects loop with the right button.
Probably worth noting, whenever I press the button designated for the effects loop the corresponding light on the foot switch has never lit up.
Have you tried the FX loop without the footswitch plugged in?
I don't give a shit if you listen to me or not
Just tried using the effects loop without the footswitch plugged in, no difference. Still won't acknowledge that there's a harmonizer and delay turned on, no change in tone whatsoever.

I noticed when I was plugging in the cables for the effects loop that the send input jack is missing a washer and locking nut. I wouldn't think that would make any difference, would it?
I definitely hope that there isn't internal wiring damage, but I did pick it up second hand so you never know. Everything else works perfectly to the best of my knowledge.

I have tested the cables, they all work perfectly. Same with the pedals. The entire rig works when I plug straight into the input without using the effects loop. Obviously it doesn't sound as good as it would through the effects loop, but with the band I don't have much a choice especially with recording plans on the agenda.

What can I do to see if there's wiring damage or test the effects loop? Should I just bring it into the local guitar shop?
The footswitch thing is troubling. Assuming the foot switch works that would point to some kind of internal fault there.

I would try replacing the V3 tube which is the one that controls the FX loop. I'm kind of doubting that is the problem at this point, but it is worth checking to see if that is the problem.

Also, do you get any signal plugging straight into the FX return? We could possibly figure out which side of the loop is not working.
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i can tell you that i have the same 5150, and there isn't anything that i can see that would defeat it for any reason other than the foot switch not working other than an internal problem.

crack it open if you feel comfortable. FYI don't poke around the guts unless you know what you are doing, tube amps can and do store lethal currents.
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Are you sure the footswitch cable is good? Mine was intermittently bad so I put a stereo jack in the footswitch housing and run a stand alone TRS cable to the amp. Works like a dream and makes the footswitch easier to handle without that cable attached.
Jackson Kelly KE3 - MIJ (Distortion/Jazz)
Jackson DKMGT Dinky (EMG 81/85)
ESP E-II Eclipse Custom (JB/'59)
ESP LTD EC-1001FR (EMG 81/60)
Fender MIM Strat

Mesa/Boogie Dual Rectifier Roadster 212
Laney IronHeart IRT-Studio
Peavey Vypyr 30
Peavey ReValver Amp Sims
TOOOO many T.C. Electronic Pedals. . .
I do actually get a signal when I plug directly into the effects return. I can actually hear the effects in the rig, I assume that the FX return is essentially serving as another input jack at this point.

Like I mentioned before, the FX send jack is missing the locking nut and washer. With some effort the jack does move around. Could this be what's up? I am assuming that it's the FX send that is the problem here, since I do get a signal when I plug directly into the FX return.

The footswitch works fine as far as switching between clean and distorted channels, it just doesn't get any response as far as the FX loop button. I suppose it could be the problem but I'm not entirely sure how I would check and see if the footswitch is broken... There wouldn't be a way to just turn the FX loop on and off manually, essentially doing the same thing as the footswitch would while just bypassing the footswitch?

I was given a receipt for the tubes that were just installed before I bought the amp from the guy, it has all new tubes so I doubt that the V3 tube is the problem here. But hey, ya never know. Probably worth having someone look at it, since I don't feel comfortable messing around with the electronics considering I have no experience with this kind of repair work.
No, the tube should be fine. One half of that tube controls the fx send and the other half controls the fx return. Since you're getting a signal on the return that should eliminate that tube as the problem.

And yes, the FX return IS just basically a input, but it's an input after the preamp (whereas the regular input on the amp goes straight into the preamp)

From all the info you've given us I'm guessing there is a fault with that jack. If it was me, I would replace it myself and see if that fixed the problem, but I don't know your skill level or what you feel comfortable doing inside a tube amp.
I don't give a shit if you listen to me or not
It looks like you have identified the problem, which is good because threads like these can be very costly to the layman. As you've seen here, people will troubleshoot from their desk having very limited knowledge of your specific situation. There are a lot of helpful people on this site, but if you were to start buying tubes and trying some of the other things like buying a new footswitch, you could've just taken it to a tech to get fixed. As someone stated earlier, if you can't open an amp and immediately (and confidently) identify the components that store charges that can kill you, take it to a technician. Better yet, if you are willing to learn, and happen to have a friend who is capable of fixing your problem, see if you can get them to do it, and also show you how to do it. Otherwise, for your own personal safety, take it to a tech.

Edit: I mean no disrespect to the people who have contributed to this thread or who have contributed to other threads of this nature. My comment was basically in the interests of the TS' safety.
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Last edited by Nolasludge at Jan 30, 2016,
^Agreed, mostly. I'd say just because you don't know doesn't mean you shouldn't try. If you don't know you should do some study and learn what's going on in the amp and learn some basic electronics safety before messing with anything.

Before I ever messed inside a guitar amp I had already cut my teeth somewhat working on arcade games at Chuck E Cheese. All minor stuff, but more than what the average person knows. My first foray in to amps was biasing a Hot Rod Deluxe which obviously must be done with the amp on. I learned everything I needed to know straight from the internet.
I don't give a shit if you listen to me or not
Thanks for all the advice guys. I will have to look into replacing that jack and will let you all know what the result is.