peavey triple x head problem with effects loop

[revjsin1]

ok so heres the situation. i was practicing with the amp master vol @ 10 preamp vol @ 4, so pretty loud. then it started making these bassy ugly noises so my first thought was failed tubes. so i checked microphonics by cranking the signal and lightly tapping the tubes. one of the preamp tubes was making noise so i replaced it. this did not fix the problem when i turned it on again the effects loop is barely working. the tuner pedal i have in the loop dosent bypass the signal on crunch and ultra and the eq pedal barely effects the signal. the power and preamp tubes are probably a few years old but i dont know if they need changing do they effect the fx loop? i really have no idea wut the problem could be: tubes, bad soldering, fx loop pots. i dont know can anyone help me figure this out?

[Enzo]

So pull everything out of the FX loop, does the amp work that way?

Now take a cord that you have TESTED and KNOW to be good - no assuming here - and plug it from FX send to FX return. Does the amp work like that?

[revjsin1]

did that, i just played a show running the amp without nething in the fx loop. it works but dosent sound nearly as good without the eq pedal running in the loop. when i hook up a good cord from fx send to fx return the amp still works. just cant get it to work right.when the eq pedal and tuner are in the loop its like the loop is barely working it hardly adds bass to the sound. so i tested if the eq was working in the loop at all cuz it hardly effected the signal so i set it up like a straight v to really hear that its kinda working and it made the amp start making those bassy ugly noises again because i cranked the lows and highs so much to test it.

[Enzo]

I know you like the sound better with the things in the FX loop, but we are trying to isolate your problem. If the amp works with an empty loop and works the same with the loop patched across, it would seem that the amp is OK, and the outboard stuff has the problem. If you put the tuner ONLY in the loop, does the amp still work OK? It sounds like your EQ unit may be at fault.

Is the EQ unit running on a battery or on a power supply?

[revjsin1]

ehh

ya thought of that too. even w/ just the tuner it dosnt wrk right, you can hear the overdrive channels through the tuners bypass. i even swithced the eq pedal for another brand new one my rythm guitar player just bought same prob. . and it seems too unlikely with the bad preamp tube i replaced and my tubes being fairly old in general. and i run both pedals through a 9v daisy chain power supply. i really appreciate your help though. iv read some of your other amp threads and i know u know ur stuff, so thanx

[Enzo]

Take your pedals and for test, run then in through the front between guitar and amp. DO they function right that way?

[revjsin1]

ya i ran the pedals through the front of the amp and they function properly.