Help! 5150 problems, buzzing, wierd ringing sound etc. Need new power tubes?

"Evil" Aidy

Mörti Viventi
Jul 15, 2007
308
1
16
Stamford, Lincs
I'm a bit of a novice when it comes to stuff inside guitar amplifiers... Although I'm competent at biasing and changing tubes in my DSL. :)

I'm helping a friend with his 5150. It's a stock Mk1, fixed bias from the 90's and STILL has the original tubes in it.

For a few weeks now it's been making some strange crackling noises, odd vibrating noises and a fairly audible high pitch ringing (kinda like Tinnitus).

We've tried cleaning all the jack sockets and power tube sockets witch electrical cleaner but the problems are still apparent.

When removing the power tubes I noticed they were all brown, almost burnt looking on the very top of each tube. One of them more brown than the others! I also noticed that one of the tubes wobbles left n right at the base of the tube, where the glass meets the plastic connector that plugs into the amp.

I did the tapping with a pencil on the preamp tubes (which are also stock) and I didn't hear anything unsual other than the light tapping coming through the speakers.

I gave the power tubes a tap too and when I tapped the wobbly tube there was an almighty KERPLONK sound!

Would a set of JJ's sort these symptons out? Any advice would be most appreciated.

P.S. How much do the transformers buzz in your amps? I did a comparsion between the 5150 and my Marshall and they both buzz quite mildly yet it isn't audible through the speakers. Presumably this normal? What causes the hiss through high gain amps? My Marshall and my buddy's 5150 hiss quite alot at high gain settings.

:erk:
 
LOL I'd be shocked if it's not the tubes. damn, the 90's???!!!

¯(°_o)/¯ WTF man?

:lol: DUDE! Yeah I was like that when I had a look at it. You should've seen the dirt n' grime I cleaned out of the inside of it. This bad boy spent several years in a damp garage too which is never a good idea!

I think a fresh set of tubes will be the first point of call. However, it has had the odd service here and there over the years by a local amp repair guy in a town nearby to me and he's always said everything is "fine" with it. Never recommended changing the tubes at all!

¯\(°_o)/¯ WTF man indeed!
 
[quote="Evil" Aidy;8077823]However, it has had the odd service here and there over the years by a local amp repair guy in a town nearby to me[/quote]

Which dude is this?

I live down the road in bourne so it will be useful to know where to go in case my VH100R ever decides to blow up.

Joe
 
That guy doesn't know anything. You do not need to run tubes for 10 years, that's absurd, and your problem. Tell your friend to buy a fresh set of tubes - including the preamp ones if they are just as old as the power tubes - and I bet you it will sound fine after that.

~006
 
Which dude is this?

I live down the road in bourne so it will be useful to know where to go in case my VH100R ever decides to blow up.

Joe

I'm not sure of the guys name but he's close to Live Music in 'Boro. I think the place is called Nippa (or it used to be). I wouldn't recommend him though. When my Marshall was "serviced" there I think all he did was hoover the inside to remove the dust. He sure as hell forgot to plug the reverb back in on the inside so i had to remove the chassis and do it myself... :mad:.

Useless!

I've heard there's a dude in Werrington that is better though and knows his stuff...
 
That guy doesn't know anything. You do not need to run tubes for 10 years, that's absurd, and your problem. Tell your friend to buy a fresh set of tubes - including the preamp ones if they are just as old as the power tubes - and I bet you it will sound fine after that.

~006

Yeah that's what I thought, new tubes needed for certain!

Thanks for the advice guys.

:)