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Blown Valve Amplifier -(:

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Posted on November 25, 2016 at 13:46:51
highfell
Audiophile

Posts: 31
Location: United Kingdom
Joined: July 8, 2013
I swapped my GEC KT88s over in my Fatman 201 amp this morning. In doing so I must have jerked one of them too hard because I now known one of the valves to have a slight rattle, which I remember hearing after I had pulled it out.

Anyway, I realised something was wrong when the sound died in one speaker and I smelt burning. When I went to the amp it had smoke coming form the bottom of the valve. Switched if off and pulled the faulty valve out which was super hot.

Let everything cool down and put in cheap Chinese valves. The amp turned on, the valves all lit up BUT no sound ...........

Any thoughts on what could the trouble be ........I guess impossible to tell.

Off to a local hi if repair shop ........

 

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RE: Blown Valve Amplifier -(:, posted on November 25, 2016 at 13:54:20
JKT
Audiophile

Posts: 454
Location: Midwest
Joined: November 26, 2002
If I had to guess, the smell was probably a smoked resistor.


"It is better to remain silent and thought a fool, then speak and remove all doubt." A. Lincoln

 

RE: Blown Valve Amplifier -(:, posted on November 25, 2016 at 13:58:15
bcowen
Audiophile

Posts: 500
Location: North Carolina
Joined: December 19, 2015
Contributor
  Since:
January 1, 2017
Not familiar with your amp, but some amps have a fuse (or fuses) on the B+ supply to the tubes. If it's blown, the tubes can still light up, just won't produce any sound as they have no B+ voltage. Check that first - the fuse(s) may be inside the amp requiring the bottom cover to be removed (be sure it's unplugged and off long enough for capacitors to discharge, yada yada).

 

"Valve out which was super hot.", posted on November 25, 2016 at 14:47:17
FenderLover
Bored Member

Posts: 12210
Joined: July 31, 2007
Contributor
  Since:
May 17, 2009
Sounds like the guts of the tube may have shorted out. You have access to a tube tester?

In addition, you may have blown screen resistor. Best to seek a good amp tech.

Good luck!

 

RE: Blown Valve Amplifier -(:, posted on November 26, 2016 at 09:18:55
highfell
Audiophile

Posts: 31
Location: United Kingdom
Joined: July 8, 2013
Thanks all. I found a local Valve amp expert - done if all his life, in his sixties etc. So let's see what the issue is. Cheers

 

RE: Blown Valve Amplifier -(:, posted on November 26, 2016 at 10:56:38
airtime
Audiophile

Posts: 8521
Location: Arizona
Joined: February 4, 2003
Best of luck. That shorted tube may have taken something else out with it.

 

RE: Blown Valve Amplifier - back from the dead -:), posted on January 10, 2017 at 03:57:04
highfell
Audiophile

Posts: 31
Location: United Kingdom
Joined: July 8, 2013

Thanks for your help. I thought you might like to have an update on my SET Amp.
My Fatman 202 has returned after its trip into hospital, fully recovered and functioning. It was a blown revsistor. attached are some photos of the damage before and after. The comment from the Amp repair guy was that it was well built. The IC chip in the top right hand corner is a DAC chip for digital input if you so want, although I don't use that option as I have a better DAP/DAC combination myself.















 

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