Herbert Power loss

[Headline]

Hi everybody,

As told in the subject my Herbert suffers of power loss on every channels.
It works well till it gets really warm, after about 5-10 min playing.
And then it goes up and down.

First I thought the power tubes were on the edge so I changed all six this morning (Groove tube EL34R) and adjusted Bias to 65mA as told.

Can the problem come from the preamp tubes? I never changed 'em..
Or could it be something else?

Thanks for answers.

 

[Headline]

Any idea?
Peter?

 

[cheftie]

You could always try a good preamp tube in place of each of your old preamp tubes and see if anythings changes. You can always change them all just like you did with the power amp tubes. However, if you want to find the weak link all you need is get one good preamp tube and go test one preamp tube at time. Hope this helps.

 

[Peter Diezel]

Any idea?
Peter?

Replace preamp tubes and see attachment

 

[Headline]

Ok I'll try that.
Thanks.

 

[Headline]

Hi,

So I changed all six 12AX7-C preamp tubes and it's still the same. :-(

 

[zerotolerance]

Hi,

So I changed all six 12AX7-C preamp tubes and it's still the same. :-(

Check the powertubes then.

 

[Headline]

First thing I did as told in my first post.
300€ for nothin'

 

[zerotolerance]

First thing I did as told in my first post.
300€ for nothin'

You can always sell the unnecessary tubes. It's 20-30% loss but still something.

 

[Headline]

Hi,

Peter I still got the problem, and I'm getting tired playing on a 5150 it's nice but not in the same league.

I opened the beast and saw a couple of welding issues on 69 and 70 caps, can this cause this issue?

Thanks for all

 

[Peter Diezel]

I see no solder issues.

Why not contact a tech ?

Cheers,
Peter

 

[Headline]

I will, just wanted to try myself.

Thanks again.