TA 15 loss of power in 5 watt mode

I recently purchased a used TA 15 in great condition, I love the amp and because of the small venues we play I very rarely take it out of 5 watts. But this past Friday at a gig I experienced a complete power loss in 5 watts at first I thought it might be a dirty input in the 77 Strat so I change guitars, same problem. But when bumped it to 15 watts I played the rest of the night with no further problems. I'm thinking tubes but any suggestions will be greatly appreciated.

Thanks

Andy925 said:

...I'm thinking tubes ...

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Hi Andy925,

A "complete power loss"? Do you mean that the lights on the amp went out, or that the volume dropped off dramatically? In the 5 watt mode, of the two output tubes, only V6 is used, so if the latter, it might be an output tube issue. Have you tried the 5 watt mode again? If you do use the 5 watt mode again and the volume drops, check to see if V6 is red-Plating.

The volume dropped dramatically. I haven't played since Friday but I will start with the V6. Thanks for the info.

When my Express 5:50 did this it was the phase inverter/driver tube. It seems that it works harder in single ended mode than push pull.

I have often thought of this happening as I use mine in Five watt mode most of the time also. Stands to reason that It would burn out the one tube faster that way as class A operation is harder on the tube than push pull . I've Thought about swapping the power tubes with each other occasionally to even out the wear and tear, but I've been to lazy to actually take the cover off and do it. I think I'll reconsider my lack of action now. The thought also occurred to me that having one worn out tube and one good one might impair the class A/B operation as well? Always thought it be a good idea to keep a spare set of tubes handy with the amp, some day I'll actually get around to that too.

allphourus said:

...I've Thought about swapping the power tubes with each other occasionally to even out the wear and tear....Always thought it be a good idea to keep a spare set of tubes handy with the amp...

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Same here, on both counts.

Thanks for all the info I did a complete retube played gigs Friday & Sat. no issues. I am trying to use the 15 watt mode more I just have to dial in the volume so I'm not over playing the room.
Thanks again.