[rollo]

   With todays technology should a new tube last longer than 30 days ?  I think so. Make sure that the warranty starts when they receive the warranty card from you. [ assumimng you get one] NOT when shipped. That will take time off your warranty as in my case.
   When you receive tube play it right away .  Once that 30 day time frame is spent you are on YOUR OWN wether you use it or not. Purchase the extended warranty if available. Especially Chinese tubes as they come from far away with shipping issues and quality control. Even tubes that are retested [ if they really do so] after receipt by the dealer. At over $ 425/ pair for some new tubes today the Manf should be thoroughly considered before purchase. At that price IMO the warranty should be one year minimum.
  I hope that my experience of melting the trannies in my amp can be avoided by others. Check out the warranty before purchase and the Rep of the dealer and Manf. It WILL pay off.
 

charles

[JohnR]

Sounds like a problem with the amp. Or at best, a poor design. (Or user error e.g. wrong fuses installed.)

[BPoletti]

Sounds like a problem with the amp. Or at best, a poor design. (Or user error e.g. wrong fuses installed.)

Could be a lot of things.  Could it be a short in a tube that would dump the high voltage directly onto the transformer windings? 

[JakeJ]

I hate the smell of burnt Form-o-var.   

Seriously though, I have had the good fortune to have no more than a PS 'lytic short out internally and it just vented.  I know the DIYers have had a total flame-out like Charles had but the average audiophile that embraces tubes without some understanding of what is going on in an amp is likely not to understand or recognize a catastrophic failure in progress and get his/her gear shut down in time.  I have LOTS of experience with diving for a switch or cord to cut the flow of 'trons.

[mjosef]

A year warranty on a power tube is asking a lot. Perhaps tube dealers should offer "extended warranties" at an additional price for some peace of mind.
Some Cars come with a warranty for 3 years/36k miles. Now I know some people who drive 30-40k miles a year...now transpose that to tube use in an amp...

[JohnR]

Could be a lot of things.  Could it be a short in a tube that would dump the high voltage directly onto the transformer windings?

Technically, the transformer is already connected to the high voltage but I take your meaning. My comment was that an amplifier should not "melt" under those conditions but do something more straightforward like blow a fuse. Bear in mind that a tube manufacturer cannot possibly know all conditions under which a tube will be deployed. Many amps from the vintage era exceed published specifications for power tubes, for example.

[dangerbird]

Melting trannies,, bummer indeed

[Quiet Earth]

A year warranty on a power tube is asking a lot. Perhaps tube dealers should offer "extended warranties" at an additional price for some peace of mind.

Without mentioning any names, if we are talking about a certain dealer who sells tubes made by the same tube manufacturer that rollo had trouble with , then you would be wise to purchase that one year warranty. I had the same trouble with my 300Bs made by that same tube manufacturer and the 1 year warranty paid off after one tube died 5 months into service.

I was not offered a direct replacement by the dealer, but an near-equivalent brand new tube set with one year warranty. The dealer stopped purchasing that particular tube because of too many failures. This all seemed reasonable to me.

I hope that we can bring more of these reliability issues to the table without harming anyone in the business or getting upset . Hopefully we can educate the consumer and give constructive feedback to the dealer and the manufacturer.

[rollo]

  The fuse was an 8 amp fuse from the factory. It should have been a 5A fuse according to the label on the back of the amp.
  could that 8A fuse be the culprit ? If the correct fuse was in place would it have blown ?
  This happened while I was out of the listening room warming it up. If I was listening I would have turned it off immediately. The amp in question is a solid design and sounded great for 5 years. No issues other than a blown cap in the power supply. We replaced every cap, resistor, diode, everything. Tested worked for about 15 days at 10 hours a day then the tube shorted. The rest is history.
   I would buy a product from that manf. again. My mistake was not sending it back right away. I assumed it would be handled differently. I had no way of testing the tube until repair was completed and that took three months. I will will never assume anything again. So I quess its my fault. BUMMER.


charles

[Quiet Earth]

If the correct fuse was in place would it have blown ?
 

Kind of sounds like it. If the manufacturer put the wrong fuse in there, then they should eat some of the repair costs. At the very least, they should have an interest in helping you get it fixed, warranty or no warranty. You should contact them and let them know about it. It's weird that the amp worked fine for so long and then you had such a catastrophic failure. I didn't know a tube could do so much damage by "going bad".

After re-reading this thread I realized that my problem was not anything like yours. When my Chinese-made tube died there was no harm done to the amplifier. Just a dead tube.

[rollo]

 The Manf. did the right thing for me. They supplied the new trannies at their cost plus shipping from China. The foreign distributor helped communicate with them for me. Well done. Now if I could only find some RCA or United 211s I'm done. Using GE 211s now. Never have enough tubes.


charles