weird 5150 problem - need help

[Fragle]

hey there,

i'm having some issues with my 5150 head.

the whole thing started with a really thin cold and buzzy sound, plus occasionally the volume would cut down all the way.
i figured my power tubes said byebye, and consequently replaced those.
in the next few weeks the problem was gone.

recently there's some weird stuff going on though. the volume would fade in and out all of a sudden....the transition between the normal and quieter volume level is pretty smooth though, so it's not like BAM, low volume....the amount the volume changes is also pretty inconsistent. sometimes you won't even notice it, but then all of a sudden the volume kicks back up and you'll go like whoa, wtf.
it's also not cutting out completely, just going quieter.

any ideas what might be wrong here?

as i said, the power tubes are rather new so i'd pretty much rule them out, but other than that, i've no friggin clue...

anyone?

 

[::XeS::]

It could be the guitar cable

 

[Fragle]

nope, it's not it has happened to me in the rehearsal room as well as in the studio, so there were two completely different cable sets involved.

thanks though!

 

[GuitarHack]

Effects Loop!!!


Plug a short patch cable between Send and Return. See if it stops. If so, clean your jacks with contact cleaner.

 

[J.DavisNJ]

Effects Loop!!!


Plug a short patch cable between Send and Return. See if it stops. If so, clean your jacks with contact cleaner.

+1, almost 100% sure this is right. It happens with 5150s quite a lot I believe.

-Joe

 

[MetalSound]

Yep, indeed. That´s what mine did, too.

 

[Colonel Sanders]

spray some contact cleaner on the end of a 1/4 jack.
shove in out in out in out (that's what she said) of the send
and do the same for return.

 

[SuperD]

Effects Loop!!!


Plug a short patch cable between Send and Return. See if it stops. If so, clean your jacks with contact cleaner.

This!!

 

[Fragle]

interesting, thanks!

actually i had some problems with the fx loop back then, but after cleaning the jacks it was gone. it was a different problem though so i didn't think of the fx loop for this issue tbh.

thanks, i'll try it and repost!

btw, is there any kind of permanent fix for the fx loop thing? as cleaning the jacks only seems to help for a few weeks max...

 

[kaomao]

it's not really the fx loops jacks, another guy on this forum posted infos about something electrical involved.
Yes even mine does this.

 

[Fragle]

alright, the story continues

first things first, cleaning the fx loop jacks had no effect at all...unfortunately.

last time i fired it up the head made a loud "whooooosh" kinda sound when hitting the standby switch (into playing position basically)....after that it sort of worked, but the sound was very thin, no bottom at all.
i just tried it again, and now the head doesn't make any sound at all, except for static hum that gets louder the higher the amp is turned up.
this affects both channels btw.
also, i went straight guitar -> amp -> cab, so nothing else in the signal chain.

any idea what might be wrong???

 

[Fragle]

so, if nobody has any idea whatsoever, i guess i'll take it to an amp tech today....

 

[LosingReality]

mine did the same thing....turned out it was a preamp tube not the effects loop....

 

[SuperD]

so, if nobody has any idea whatsoever, i guess i'll take it to an amp tech today....

Sorry my man, my money was on the FX loop jacks...

 

[sirscratch01]

Dude fuck!! mine does EXACTLY the same thing and I can't figure out what the hell is wrong with it. I replaced all the pre amp and power tubes and tried contact cleaner on all jacks and tube sockets and nothing. It works perfectly when it wants to then after a while the gain/lowend/volume all take a shit. Sometimes it does that woosh thing too. Please let me know what your amp tech says cuz ive been too broke to take mine in but i miss it haha. It's basically become a studio ornament that i break out every now and again and pray it works (usually doesn't)

 

[theunforgiven246]

You could always contact peavey

 

[colonel kurtz]

well...if you changed all the tubes and cleaned the FX send/return really well, my money would be on a toasted transformer

 

[TheWinterSnow]

had the same problem, but it was my cable in the FX loop. COnsidering that, When I opened up my amp, i noticed that some of the molex style connectors are not put together too well. I would advise checking and making sure that all the ribbons that connect the various boards are seated well as well as the taps from the Transformers and connected well, but if you have no EE experience when you take a look, you willhave no clue WTF is going on and if you touch the wrong part, it will give you a shock of your life.

 

[JeffTD]

Oh shit its broken buy mine!

 

[colonel kurtz]

had the same problem, but it was my cable in the FX loop. COnsidering that, When I opened up my amp, i noticed that some of the molex style connectors are not put together too well. I would advise checking and making sure that all the ribbons that connect the various boards are seated well as well as the taps from the Transformers and connected well, but if you have no EE experience when you take a look, you willhave no clue WTF is going on and if you touch the wrong part, it will give you a shock of your life.

this post just reminded me that i shocked myself last night

not sure how it happened...all i did was touch a breaker, but i got 110v right up my ass!