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Author Topic: Momentary loss of power after output tube swap  (Read 1393 times)

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Offline sbelyo

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Momentary loss of power after output tube swap
« on: December 19, 2011, 08:42:53 AM »
My Crack was on for about two hours.  I shut it off, took the output tube out and put another one in.  When I turned it back on, I got nothing.  No sound, and I didn't see the filaments light up. 

I unplugged everything, took both tubes out and flipped it over.  I visually checked all my connections and they looked solid, no boken leads or wires.  The only thing I noticed was that one of the output cap bleeder resistors looked burnt.  It put a meter on it and it read 2.4K same as the other.

I put the tubes back in and it fired right up, and got sound.  I checked the offset and it was fine and within limits.

What could've happened.  Did I do something by having one warm tube and one cold tube in the same circuit?  If so, did I stress out my input tube?
« Last Edit: December 19, 2011, 08:45:35 AM by sbelyo »

Offline Jim R.

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Re: Momentary loss of power after output tube swap
« Reply #1 on: December 19, 2011, 09:06:23 AM »
More than likely you either have a loose connection in there somewhere, or you simply cleaned the tube pins a bit better when you reinserted the tube.

If all seems and sounds normal, I'd probably just forget about it but pay attention for any noises or other changes in the sound.

HTH,

Jim
Jim Rebman -- recovering audiophile

Equitech balanced power; uRendu, USB processor -> Musette DAC -> 5670 tube buffer -> Finale Audio F138 FFX -> Cain and Cain Abbys near-field).

s.e.x. 2.1 under construction.  Want list: Stereomour II

All ICs homemade (speaker and power next)

Offline sbelyo

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Re: Momentary loss of power after output tube swap
« Reply #2 on: December 19, 2011, 10:05:49 AM »
It sounds and performs the same.  In the assembly process many months ago I nicked one of the transformer magnet wires that is wound around the solder tab on the transformer but I fixed that solidly and it's worked for months.  That was the first thing I checked because this thing had zero power.

If it cuts out again, I'll reheat that joint.  I didn't bother at the time because it was working.