Herbert Keeps Blowing Fuses -solved-

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Jim86

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I have had my Herbert for about 9 months now in which I purchased used. I believe it is
a 2009, but I am not 100% sure. Mine has the external bias points.

Ok here is the situation and problem. When I purchased the amp (used) it had 6550s
in it for tubes. The dude I purchased the amp from gave me 6 TAD EL-34s as well.
Now if they were "used" tubes or brand new, I do not know.

With the 6550s, it did not sound all that great but I did not have any problems (that I know of) with any fuses blowing, meaning, I don't recall or not if any of the fuses were blown which I am pretty sure they weren't. With that said, I did not play the amp that much because I didn't care for the tone that much and was waiting for a friend of mine to have some time so we could change to EL-34s. So could have a problem happened?...unknown
because I did not play it much.

A couple weeks later, brought it to my friends house. Swapped out the tubes and biased it up with a Bias Rite. Now after what I had read on this forum, I was a little worried with it coming with 6550s, but when we saw what the 6550s were biased cold, I was not worried
about any possible damage to the amp. FYI..........this amp looks brand new so it does not look like it was played hard or played out.

So we biased it up with the EL-34s, and now I keep blowing fuses, and it has been in all
3 positions. I realize there could be a bad tube or two, but all 6? This is what has me worried.

So here are my questions.

1.) could the bias have drifted to a point where the fuses keep blowing?

2.) would a bad tube or two effect the others to go bad sooner?

3.) or my biggest fear, could there be something else wrong with the amp if it is not
the tubes and if so, what could it be?

Any and all help will be greatly appreciated.

Thanks
 
Please first run the amp without power tubes and see if it blows any fuses.

Best,
Peter
 
Peter,

Do I keep it in standy by mode or do I engage it if I were to play?

Also, should I have a guitar or just a 1/4" cable plugged into the input jack?

Last question, how long should I run this test?

I just want to make sure to follow your exact instructions.

Thanks

Jim
 
First turn on the main switch, then the standby switch.

No guitar cord necessary.

If the fuses don´t blow, your power tubes are bad.
If the fusses get blown the amp needs a tech.

Best,
Peter
 
Peter Diezel":1zon5lj9 said:
Please first run the amp without power tubes and see if it blows any fuses.

Best,
Peter
This is good trouble shooting to know. Having an outboard dedicated tube tester is much more expensive than using what one already has. I would have thought this would harm the amp.
 
Jim,

please order a sextett of KT77-JJ.

Best,
Peter
 
Peter,

I did the test it seems it should be the tubes. It will be a couple of weeks before I get the tubes and get them in and biased. I will keep you posted.

Thanks

Jim
 
I just realized I posted that twice LOL.......dah on my part !!

Jim
 
Just out of curiosity, are you putting in ALL EL34'S, or only a pair or two?
 
Yes, I am do all EL-34s - Actually KT 77s as Peter recommends

Jim
 
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