5150II Low knob not working

[Genius Gone Insane]

I think this might be a tube issue but I want to see what you all think.

My 5150II started acting up yesterday, significant volume loss, and the Low knob has little/no effect on the sound (all the others do work). The amp is missing all it's low end. Do you think this is a tube or is it bad connections? Anyone had this problem before?

Thanks!

 

[everybody's x]

Im having this issue with my boogie as well
the bass and mid knobs do nothing
I switched all the tubes and with no change at all
the head was built in 95 maybe time for a cap job?
I'm hoping someone will chime in with an easy (cheap) answer

 

[53Crëw]

Probably a tube issue if the amp has lost volume..... Most likely power tubes, but on occasion a preamp tube can do this. (preamp tube last much longer than power tubes.)

Regarding the recap on the Boogie... The caps should still be okay I think. Mines a '92 and it still sounds good. Usually, this is something you need to start considering on an amp that's at least 20-25 years old, and the problem is usually noise, or a flubby low end. Boogie also uses good components that may last longer than the caps in old vintage amplifiers, as well. If I had an mid to late 70's amp, I'd consider redoing the caps, but a '95 should be fine I would think.

Cheers.

 

[Notuern]

If the distortion seems weaker or different, its probably a preamp tube, if not, its most likely a poweramp tube.

 

[SuperD]

Might want to check the FX loop return jack on the 5150. A little contact cleaner on a jack and plug it in and out a few times to clean it...happens often, that may be all it is ...lets hope.

 

[Descent]

I had this on my 5150, sent it off to peavey for retube/service etc and it came back fine so quite possibly tubes.
However on a jcm900 i used to own i had similar thing and it was (as superD said) just a contact problem on speaker jack output, some contact cleaner fixed that.

 

[J.DavisNJ]

+2 On the effects loop jack(s)

I had the SAME exact thing happen to my old block letter. The volume drop, no balls, no low end. Those jacks can make 5150s do wacky things.

Try putting a cable between the two effects loop jacks. That should solve it. Or, replace them/clean them. Rule that out first before spending money on tubes.

-Joe

 

[SuperD]

Yup, I speak from experience...my block letter had exactly those symptoms and the FX loop jacks were the problem. And it's not limited to 5150's, it can happen with any amp...

 

[electrikmt]

Im having this issue with my boogie as well
the bass and mid knobs do nothing
I switched all the tubes and with no change at all
the head was built in 95 maybe time for a cap job?
I'm hoping someone will chime in with an easy (cheap) answer

The rotary bass and mid knobs on a lot of Mesas (ie Mark series) aren't supposed to have a lot of effect on the sound, that's just how the EQ works. What model do you have?

 

[everybody's x]

its a 50 caliber plus, I've had it since 96, this is definitely a new issue.

The treble knob normally is your main tone control , but I mean the bass and mids do NOTHING at all.

the graphic still works

 

[Genius Gone Insane]

Hey guys, thanks a ton for the help. I bought a $6 can of contact cleaner, took the 5150II out of the wooden casing and sprayed the shit out of everything (knobs, pots, jacks, the whole board). Worked like a fucking charm. I think I'm going to try contact cleaner on my girlfriend, maybe she'll work better now too.

 

[SuperD]

Good news !!
And, um, good luck with that girlfriend thing...

 

[everybody's x]

kick ass

 

[sw4rm]

hey, i've been having a problem with my 6505 which while not the same as the other users problem may be similar. my set up is as follows;
guitar-tuner-noisgate-6505.
sonic maximizer in effects loop.

The problem i have been having is a short but dramatic drop in volume during playing. all leads replaced and the problem persists. the signal is reaching the noise gate as i can see by the lights that the signal is making it.

The lights on the sonic maximizer go out when the problem occurs. (they are numbered so basically they return to zero.

Drop lasts about 1/2-1 sec, usually happening at higher volumes (post gain 3 1/2-4)
Usually when playing lower palm muted riffs.

Could this be a unit fault, an fx loop fault or could it have something to do with the volume and amount of low end sound although maximizer never clips.

Thanks in advance

 

[greyskull]

sonic maximizer in effects loop.

AARRRRRRRRRRRRRRRRRRRRRRRRGGHGHGHGGGGGGGGGGGGGGGGGGHHHHHH NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.


take the damn thing out and put it on ebay.
problem solved

 

[nwright]

^Actually, the idea of taking it out of the loop should solve the problem.

If the lights are going out on the maximizer, sounds obvious that that is where you should start in diagnosing the problem.

 

[everybody's x]

AARRRRRRRRRRRRRRRRRRRRRRRRGGHGHGHGGGGGGGGGGGGGGGGGGHHHHHH NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO.


take the damn thing out and put it on ebay.
problem solved

plus one billion

 

[SuperD]

And clean up all the contacts, jacks etc. And at least try it without the sonic maximizer, 'K?

 

[sw4rm]

ohhhhh contoversial! haha.
so do the guys who suggest removing the SM completely feel that the problem is caused by having that in the effects loop or do you just not like them?
i appreciate the suggestion of taking it out completely but i'd quite like to know why i am having this trouble.

thanks

 

[SuperD]

If the problem is with dirty or corroded jacks, particularly FX loop jacks,and I always suspect this first, then the problem will persist even with NOTHING plugged into the loop. I was suggesting you disconnect whatever is in the loop and see if you still have a problem.
Although, I'm still going to suggest you at least spray some contact cleaner onto the end of a patch cable and plug it in and out of all the jacks, usually all the repair that will be required. But hey, while you're at it you might as well give her the once over and clean up all pots etc. Never hurts. Worst case scenario, if it IS a faulty jack, is that you will have to replace a jack.
Occam's razor ( sometimes spelled achem or ockham...doesn't really matter ) states that all things being equal the simplest explanation tends to be the correct explanation...I can't tell you how many times I've torn my hair out over a glitch only to (eventually ) discover the amp was on stand by, or something not plugged in properly...etc. It COULD be something serious, but I wouldn't bet on it !
And I have no experience with a sonic maximizer specifically, although I did not like a Rocktron exciter I used for a while. Tone is subjective. What I like/dislike is not necessarily what you'll dig.
That being said...you can't teach experience, and the fellows on here have experience. I have learned a great deal, and I'm an OLD guy !!
So I'm hoping it's a simple dirty jack.