major 5150 problem

[PallarAndersVisa]

in the past few days, my amp has come to a problem. Note I havent changed anything, or even moved the amp around. all of a sudden a few days ago, My amp has sort of lost it's "volume". I can turn the post gain up to 5 and it wont even break bedroom level. its very weak. My friend has a 5150 as well and he had some spare working power tubes, so we swapped them in one at a time, and nothing changed. So we swapped them all, and still nothing.

Any Ideas on what might be wrong? we are in the process of replacing all the pre-amp tubes right now with some of his spare ones. I will update this in a few minutes

[jazzman]

Re: major 5150 problem

My guess without seeing the amp is the preamp tube. I'm not sure of the 5150 tube layout, but generally it is the tube closest to the input jack. Or at least on most amps it is. I retube my amp at about every year or so.

[krimson]

Re: major 5150 problem

Have it serviced. Sounds like the board needs to be resoldered. Mine used to do the same thing. Cost me about $85 to fix. I bought mine used at a pawnshop and they had two. The fist one I got was messed up like you mention and the second which I kept would only do it occasionally. I tried the changing preamp tubes with no resolve.

[jazzman]

Re: major 5150 problem

Ouch! That sucks. Sounds like they "cheaped out" on components. Perhaps the new tubes won't work. BTW are the tube sockets mounted solid or mounted to the circuit board? I used to have a classic 50 and changin' tubes was scarry. When you push the tube in, the circuit board would bend. I used to take the back off and hold the other side with my hand.

[jazzman]

Re: major 5150 problem

So, What happened?

[JerryP]

Re: major 5150 problem

Plug a cord in and out of the effects loop jacks a few times. The will clean them up sometimes. Sounds like dirty loop jacks to me. You can try plugging a cord in the loop as a jumper to see if that's it.
Jerry

[PallarAndersVisa]

Re: major 5150 problem

sorry for the late update

I took all of my pre-amp tubes to the shop and he them tested. One of them had a gas leak, so I replaced it and all is well [img]/images/graemlins/smile.gif[/img]

[Sukisyn]

Re: major 5150 problem

That is good to hear. [img]/images/graemlins/smile.gif[/img]

[PallarAndersVisa]

Re: major 5150 problem

ack! now its making a high pitched squealing noise. Its pretty low in the mix and you cant hear it while you play. Its not feedback thats for sure.

one problem after another, i swear [img]/images/graemlins/smile.gif[/img]

[bluebullet]

Re: major 5150 problem

sounds like the tube they sold you is microphonic take it back and get a new one and that should do it

[PallarAndersVisa]

Re: major 5150 problem

ok so I switced the order of the pre amp tubes and that got the noise away. but god damn another problem just arised! I cranked my amp up to about 3, which is pretty loud for bedroom levels, but no ones home. So im playing for about half an hour all of a sudden, the volume just cuts right in half. I can now crank it to 5 or 6 and it still wasnt as loud as when it was at 3. Are my power tubes going now?

[lerxstcat]

Re: major 5150 problem

Go to www.fjamods.com and email the owner. I forget his name but he's posted here a bit, and his specialty is the repair and modding of 5150 heads, among others. He can probably help you via email, or if not by sending it to him for whatever repair's needed.

[JerryP]

Re: major 5150 problem

[ QUOTE ]
Go to www.fjamods.com and email the owner. I forget his name but he's posted here a bit, and his specialty is the repair and modding of 5150 heads, among others. He can probably help you via email, or if not by sending it to him for whatever repair's needed.

[/ QUOTE ]

That's me JerryP! Re-read the post I made above about the effects loop jacks. It's a very common problem and easy to fix.
Jerry

[PallarAndersVisa]

Re: major 5150 problem

oh wicked. You're the guy i just emailed :lol

I will give your effects loop thing a try

[Chuckracer]

Re: major 5150 problem

JerryP is indeed the man. He fixed my "hummer" Boogie Studio .22 when I was ready to use it for target prectice. Heck of a good guy, and REALLY knows his stuff when it comes to these amp thingies.

Jerry gets the full "Fuckin Dude" endorsment from Chuckracer.