RM50 power tubes wearing unevenly..

[withmittens]

no red plating and each tube jumps 10 to 11 Mv when blasting an open chord, master volume fairly high.

left tube is biased at 21 Mv, Right at 33Mv, more or less at rest

 

[kc2eeb]

OK,
They're both going up equally, that's good.
10 to 11 mv is very small, so you're playing very loud at all.
No red plating is excellent
If you switch the tubes, does the difference in bias follow the tube?
Usually, when I play loud, the mv will go over 100 mv(ma).
(I play loudly)

 

[withmittens]

the difference follows the tubes. yes if I turn the amp up, way up the Mv does go higher, but equally so, 30-40 or 50Mv if I pound it. It sounds wonderful, no weirdness

 

[JKD]

I have had this happen with many tube sets over time, but havet really tested it lately so I'm not sure if it still happens with my replacement RM50 board that I put in a few years back or not...have to check

 

[kc2eeb]

I replaced my PA board and the OT about two years ago.
The fact that the current draw does go up evenly and, more importantly, the amp sounds wonderful, would make me think the amp is OK.
Of course, If I had the amp in front of me, I'd have it out of the box and checking voltages.
You haven't blown any fuses, no red plating (very important), and it sounds good.
You could always have it checked by a tech, BUT, I'd only take it to someone who knows the amp and has worked on them before.

 

[withmittens]

thanks for all the input. I took it about an hour away under warranty a couple of years ago, although he didn't seem great or like he particularly cared, he may be the only one. Since it couldn't hurt to change the OT I may get the Heyboer for around $90 and bring it in. Although my local guy seems to know his stuff and works on all manner of expensive amps, he has a massive attitude and charges without letting you know what he'll be doing....leading to a big bill and a shrug

I appreciate all the info given here

 

[kc2eeb]

I have done repair and service for guitars and amps in the 60s and 70s to firearms in the 80s, 90s and 00s, and aerospace components in the 10s and I never understood how some people could be such pompous, egotistical asses. Really.
A Heyboer tranny would work just fine, if you need it. He may resent that you bring in a transformer rather than letting him get it and make the profit. Or, maybe not. Who knows.
One thing I never did was do a whole bunch of work and then hold the item for ransom. I always tell the customer first, then do the work.

 

[withmittens]

I agree, kind of a bad idea