F30 Tube Issue...or More?

[NDRU]

I noticed recently that the left power tube's plate was glowing on my F-30 after the sound went a bit fizzy.

I replaced those with some new Mesa EL84's, but the left one glowed slightly again. I then switched the position of them, and the glow followed the tube--it now glowed on the right!

I replaced those tubes, thinking they could possibly be defective, and the same thing happened. First the left tube glowed, then when I traded slots, the right. Sound-wise, it's working fine, but I don't want to use it.

It seems like too much of a coincidence that the left one could keep glowing, and I think something must have blown in the amp, but then the fact that the glow is following the tube makes me wonder if maybe it is the tubes after all.

Any advice, before I take the amp to a tech?

 

[NDRU]

I should mention that the first tubes that glowed wer not Mesa tubes. They were probably not the correct rating, as it turns out.

Could I have damaged something that makes one tube run slightly hot, but otherwise work perfectly?

 

[dennq45]

I have had single tubes red-plate on me also. Prolly just a bad tube. I always keep a few xtras around.

 

[NDRU]

That would mean that 2 of the 4 I bought this week were bad. Certainly not impossible.

That would be good news for about my amp, but a sad statement about Mesa tubes!

 

[satisfied5582]

i don't like mesa tubes. in my old rectifer, which i bought brand new, it blew two power tubes then one rectifer tube a month after i bought the amp, all mesa tubes. i took it in to have it looked and the guy said every thing fine and working properly and it had to be bad tubes because there was nothing wrong with the amp, now that is a *****, three bad tubes in one amp. i put jj's in it and never had a problem the rest of the time i owned the amp.

 

[NDRU]

My amp tech said he saw that a couple of the contacts that hold the pins on the power tubes were loose, and not in contact with the pins. He thought that the amp couldn't bias properly with the tubes because of that.

I think I (or the guy I bought the amp from) need to be more careful when replacing tubes.