Put a bad tube in and saw a little smoke after a minute or two

sbelyo · 1590

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Offline sbelyo

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on: December 25, 2015, 11:48:52 AM
I broke a cardinal rule and put in a pair of tubes before testing them.  One was fine, the other had grid leakage and was shorted.  The tube was in there for two minutes total, I plugged in my headphones and had music from one side and crackling from the other.  I went to unplug the phones and saw a little light smoke from the vent and a funny smell.

I powered down and removed the tubes.  All the components looked ok but the smell seems like it came from the C4S board.  I installed new tubes and played the amp for an hour or so.  It seems fine and plays normal so I think I'm ok.  What should I check?

Has anyone ever fried anything from a bad tube?


Offline mcandmar

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Reply #1 on: December 25, 2015, 12:02:11 PM
I would run through the resistance checks in the manual to make sure none of the resistors got toasted if there was a short.

I once stumbled upon a new tube that had the filament wiring shorted against the grid, it made a rather loud bang when the tube warmed up and started to conduct!   Since then i always run new tubes through my tube tester before they go near the amp.

M.McCandless

Offline sbelyo

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Reply #2 on: December 25, 2015, 03:51:15 PM
Amen to that...  I'll check the resistance to see if anything happened


Offline sbelyo

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Reply #3 on: December 25, 2015, 05:39:22 PM
resistance checks out ok...  Voltage check tomorrow


Offline sbelyo

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Reply #4 on: December 27, 2015, 08:55:37 AM
Voltage check out ok...  Looks like I'm in the clear.


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