Fender 5F1 Champ dead

[2TMike]

Hi, thanks to everyone for the help and suggestions.
This is where I've got to today.....
Visual inspectio again and honestly everything looks like new, crisp paint on all the resistors and tubes.
So, pulled all the tubes and powered up. Loud hum noise gone and all fuses held ok.
Next replaced the rectifier tube only. Powered up again and same result
Then replaced the preamp tube as well as the rectifier and again the same, silent amp and no blown fuses. Power tube stayed out.
Pulled the rectifier tube again to check which was pin 8 for the voltage check, replaced it and immediately the main 2A fuse blew.
So I'm a bit stuck until I can pick up a new 2A fuse hopefully in the morning.
Cheers
Mike

[2TMike]

Update,
2TMike, check that R11 mounted on the power tube socket measures 470 ohms

Just measured it at 460 ohms
Mike

[Enzo]

Not a probllem.


OK, just an odd thought. Look on both the rectifier tube and the power tube. Is it possible teh plastic peg in the center of the ring of pins is broken off? That would allow the tube to be inserted in the wrong way.

[Chuck H]

Not a probllem.


OK, just an odd thought. Look on both the rectifier tube and the power tube. Is it possible teh plastic peg in the center of the ring of pins is broken off? That would allow the tube to be inserted in the wrong way.

I thought about that too, but figured that info wouldn't been included if that were the case.?. Good to have it on the table for consideration.

[Enzo]

but figured that info wouldn't been included if that were the case

Never assume. And no offense intended, but when there is a problem troubleshooting a two-tube circuit, I can't assume that "Oh, don't they just plug in?" isn't part of the problem.

[2TMike]

Hi, no the tube location pegs are perfect and the tubes seat as you would expect
Mike

[g1]

Sounds like you may have an intermittent rectifier tube. Do you have another to try?

[2TMike]

Only if it is the same tube as the one in my Blues Deluxe, I'll check....but I need to get a few 2A mains fuses first in the morning
Mike

[Chuck H]

Only if it is the same tube as the one in my Blues Deluxe, I'll check....but I need to get a few 2A mains fuses first in the morning
Mike

The Blues Deluxe doesn't use a rectifier tube and the power tubes are a different model.

[Jazz P Bass]

I have already gotten amps in where the rectifier tube was inserted in the output tube socket and the output tube in the rectifier socket.

"Can't understand why it's blowing fuses."

[Randall]

"I have already gotten amps in where the rectifier tube was inserted in the output tube socket and the output tube in the rectifier socket."

So have I.

[2TMike]

OK, back to checks.....
The power fuse fitted that just blew for some reason was 1A not 2A. Replaced with a 2A fuse and powered up with rectifier and preamp tubes fitted. As before, no noise and all fuses good.
DC voltage measured across pin 8 to ground on the rectifier tube is 465V.....
Mike

[Dave H]

The power fuse fitted that just blew for some reason was 1A not 2A.

Was the 1A fuse a fast blow type? I'm in the UK too. I have 4W, 15W and 30W amps running with 1A T mains fuses and they never blow. Do the fuses hold up now with the power tube inserted?

[2TMike]

Hi, yes it was a fast blow main fuse, but the amp had been on and off many times in a short period whilst I was checking things so perhaps its an unconnected event.
Power tube back in and right back to the start. Loud hum, no response to input or vol knob but all fuses holding ok

[Chuck H]

Get that old power tube outta there! You almost certainly need a new one. It's the first suspect and always has been.

You could put one of the power tubes from your Blues Deluxe in temporarily. It's not the right tube, but if it's just used for an initial function test it shouldn't hurt anything. But then put it back in your Blues Deluxe and get a new 6V6 for the Champ.