2. amps-preamps
  3. 186564-17425

Can a tube short without blowing?

Loud pop, the left channel went silent.  All tubes in the integrated amp remained lit and appeared to be normal.  The left channel tube fuse had blown.  Can a tube short and cause a fuse blow but without causing the tube to fail?  It is probably just a bad fuse but I’ve never had a fuse fail without a cause after initial startup (e.g., first 20 hours).   There are 125 hours on the Cary SLI-80HS integrated amp now.

‘Also, can a preamp section tube at EOL cause something like this? After the first 100 hours of run-in I replaced the 6922 tubes with a pair of beloved NOS tubes with many hours on them. They also remained lit throughout the event.

txp1
oddiofyl's avatar
oddiofyl
3,699 posts
 

A tube can glow but have an internal short. Hopefully it just took out a fuse. 

tomcy6's avatar
tomcy6
2,578 posts
 

Tube testers for preamp tubes have a short test on them and they tell you if a tube fails this test to turn off the tester and dispose of the tube.  So I guess that means yes to that question.

txp1 OP
148 posts
 

@oddiofyl @tomcy6  Thank you!  Although I’ve used tube equipment for many years I did not know either of these facts about tubes.

 I was lucky— it was just a prematurely bad fuse.  I’ll keep my eye on the 6922s.  I wish I could find another pair (NOS Ediswan 6922).  So far, no luck.

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