'65 BF Twin Reverb - pulled V1 tube, killed amp

I assume you checked the fuse?

 

Have you checked the amp's fuse?

If the fuse is ok are the tubes warming up and glowing like usual?

 

I'm assuming this is an original, not a reissue?

With the tube out, a socket pin may have leaned over and shorted to another one inside. Check the fuse, replace it if needed, and see if it powers up. Fingers crossed it didn't short plate voltage to the heater circuit and damage the winding.

 

Chances are pulling the V1 tube had nothing to do with the power failure.

Powering a vintage amp up is when the most failures occur - normally when the standby is flipped after warmup, but it's not uncommon for a failure to occur hen the power switch alone is turned on.

Obviously, as previously mentioned, the fuse is the first thing to check. IF nothing is lighting up - are you saying there is no pilot, no filaments lighting - or things are lighting up but there's no sound?

Either way - how long since the amp has been serviced, and what was done then? If it's never been serviced that you are aware of just take to a qualified tech right away.

 

Could be a bad power switch. Odd coincidence if it is. Have you tried turning it on with the tube put back in?

 

Have you tried a different wall outlet? Maybe a breaker tripped.

 

What you got there is a mysterious mystery. Time to get out the volt meter and start figuring out where the voltage stops. **Note: only do this if you know how not to kill yourself working on an amp.**

You said it's not blowing fuses. Did you remove the amp's fuse and test it, or replace it with a known good one? That's the most common point of failure. A bad power switch is not unheard of, but not especially common, either.

 

Give it a good once over with your nose. Anything catastrophic like a burned resistor or transformer winding, or blown cap, puts out a nasty, distinctive aroma.

A complete refusal to power up, coupled with not blowing the fuse, is worrisome though. I like Fred's idea - check the outlet for power first before you get into the chassis. You might have tripped a GFCI if your outlets are supplied by one. It only takes a few mA of leakage to ground to trip one.

 

'65 BF Twin Reverb - pulled V1 tube, killed amp

I'm sure it wasn't intentional on your part. A good attorney can probably get you off with charge of amp-slaughter.

It does sound pretty damn strange though and probably not related to the tube at all. Sounds more like some component just reached the end of it's useful life and up and quit. It's a 50 year old amp and that does happen.

 

Multimeter troubleshooting:

Do the power switch terminals (both) have AC wall voltage when the power switch in ON? Does the fuse have the same voltage on both terminals?

If yes:

Is there high voltage AC from the power transformer at the rectifier tube? Is there 5v AC on the rectifier heater wires from the power transformer? Is there 6.3v AC at the heater wires at the first power tube and the last preamp tube?

If yes:
Is there high voltage DC at the big filter caps?

If yes:
Record all the DC voltages on all the tubes and post it here.

 

I just came to check the thread and was going to say just about exactly what rob said.

 

It is good to know how not to kill oneself in there. Have you taken measurements of live voltage before? Do you know where to check for that AC input voltage? Do you know where the rectifier circuit is....since there is no rectifier tube? Do you recognize the heater circuit? Do you know the tube pin outs so as to be able to take voltage measurements there? Have you studied a layout...and/or a schematic? Have you read some tube amp repair/maintenance literature?
I am a cautious sort....so I have to ask these questions. However....learning is...no matter your level of experience or understanding, it is your world there. One hand behind the back...one hand behind the back. A shock with one hand in contact with the voltage can hurt. A shock with both hands involved can kill. Don't ask how I know....I don't have nine lives left...even though I am one cool cat!! LOL

 

V1 is not your problem IMO. The symptoms point to an intermittent connection in the power supply. It could be dirty connectors in the On/Off switch or a bad switch as bparnell57 suggested or a bad power chord.