Bottlehead Forum

Bottlehead Kits => S.E.X. Kit => Topic started by: sbelyo on December 25, 2015, 11:48:52 AM

Title: Put a bad tube in and saw a little smoke after a minute or two
Post by: sbelyo 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?

Title: Re: Put a bad tube in and saw a little smoke after a minute or two
Post by: mcandmar 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.

Title: Re: Put a bad tube in and saw a little smoke after a minute or two
Post by: sbelyo on December 25, 2015, 03:51:15 PM

Amen to that...  I'll check the resistance to see if anything happened

Title: Re: Put a bad tube in and saw a little smoke after a minute or two
Post by: sbelyo on December 25, 2015, 05:39:22 PM

resistance checks out ok...  Voltage check tomorrow

Title: Re: Put a bad tube in and saw a little smoke after a minute or two
Post by: sbelyo on December 27, 2015, 08:55:37 AM

Voltage check out ok...  Looks like I'm in the clear.