Hello,

I picked up a heathkit vacuum tube audio integrated amp this weekend
that uses
the tube compliment 12AX7's, 12AU7's, 7199, 5AR4 rectifier, EF86 and
four 7159 power tubes.

The first time I turned on the amp, I noticed the 7159 power
output tubes were glowing very brightly, too bright it seemed to me.

The amp did play, but not real well but knew it was going to be
marginal
anyway.

I noticed the thin metal housing around all the
filaments, cathodes etc. was actually glowing orange
over almost the entire height of the tube guts. I thought
this looked unusual.

So I shut it down to investigate. All four 7159 tubes in the
amplifier were doing it. The tubes also felt incredibly hot after the
little 2-min session.

So what do you think? is that normal or is the amp
over jucing the tubes?

thanks,

Andy Rein

Hi Andy,

Don't plug it in again!!!!! What you describe is *not* in any way
normal. Your output tubes are experiencing runaway which can occur for
any number of reasons. It will destroy the tubes in short order. If
you don't feel competent to troubleshoot and repair the amp, you should
take it to a tech.

Good luck,

Raymond

andyboy wrote:

Hello,

I picked up a heathkit vacuum tube audio integrated amp this weekend
that uses
the tube compliment 12AX7's, 12AU7's, 7199, 5AR4 rectifier, EF86 and
four 7159 power tubes.

The first time I turned on the amp, I noticed the 7159 power
output tubes were glowing very brightly, too bright it seemed to me.

The amp did play, but not real well but knew it was going to be
marginal
anyway.

I noticed the thin metal housing around all the
filaments, cathodes etc. was actually glowing orange
over almost the entire height of the tube guts. I thought
this looked unusual.

So I shut it down to investigate. All four 7159 tubes in the
amplifier were doing it. The tubes also felt incredibly hot after the
little 2-min session.

So what do you think? is that normal or is the amp
over jucing the tubes?

thanks,

Andy Rein