#1
Hi there, i'd like a bit of help from the more experienced lads please.

My 5150iii 50w drops in volume after about 20 mins, quite a considerable drop.

I'm running it at around 2.5 -3 and when it drops off it goes down to what would be about 1. This is happening on the blue and red channels.

Have i got valve issues? Where do i start please?

Thanks.
#2
Sounds like you'll need new power tubes.
Quote by TheSennaj
And well yes, I'll enjoy the carpal tunnel and tendonitis, because trying to get one is clearly smarter than any word you have spoken thus far.
#4
Could be a tube going weak...

When I first got my Super Reverb it was doing the exact same thing, 15 to 20 minutes and sounded like you pulled a power tube out. I talked it over with the owner of a vintage guitar shop, we both thought it was a bad output transformer, I had already ruled out tubes by swapping them, I had 3 sets.

I started replacing capacitors, waiting for a good job that would pay for the transformer, ($100 plus), it was around 35 years old and the electrolytic ones start to dry out after 20 years or so, I replaced every cap in the thing. Replaced the last of the Orange Drops (common name) and it started working right, still working perfect as of last weekend's gig after 10 or 12 years.

Try known good power tubes, and rectifier tubes if it has them, that may be a solid state rectifier amp, I'm not sure. Get one or two good preamp tubes and swap those from one position to the next to rule out preamp tubes, and if you rule out tubes, have a tech look at it. Once tubes are ruled out, it's probably a weak capacitor somewhere or could be a weak output transformer.
Hmmm...I wonder what this button does...
#5
No rectifier tubes in the III.

Definitely power tubes. Replace them. Maybe buy a spare set too.

Stock is usually JJs in these. Fender just scrapes the labels off. Sometimes they miss a bit of red paint from the logo.

Get JJs. Or you can experiment.
Ibanez Prestige RG852MPB
Ibanez Prestige RG652KFX
ESP E-II M-1
LTD AW-7
Schecter Loomis NT
EVH 5150 III 50
PRS 212 DB
Line 6 POD HD500X
Deadhorse OD/Boss HM-2
Last edited by lemurflames at Jan 22, 2015,
#7
Hi again
A pair of JJ matched power tubes and a couple of JJ pre-amp tubes arrived today.
Do i just swap the power tubes and see how it goes?

Thanks.
#8
Quote by Lozhaze
Hi again
A pair of JJ matched power tubes and a couple of JJ pre-amp tubes arrived today.
Do i just swap the power tubes and see how it goes?

Thanks.

yeah

to get the optimal life and tone out of it the power tubes should be biased, but it will not hurt anything to put the new tubes in and test it.

remember all the tubes pull straight out (no twisting/turning)
2002 PRS CE22
2013 G&L ASAT Deluxe
2009 Epiphone G-400 (SH-4)
Marshall JCM2000 DSL100
Krank 1980 Jr 20watt
Krank Rev 4x12 (eminence V12)
GFS Greenie/Digitech Bad Monkey
Morley Bad Horsie 2
MXR Smart Gate