Tube Amp Archive

Edit. Its cool, I figured it out.

Well it looks like it was the secondary of the PT. I wired up the primary of the new one and then jumped the bias supply on one of the high voltage wires from the standby on the secondary with the ct lifted and no bright light. I measured across the 2 high voltage wires and I get 566 VAC where as be...

I salvaged a 1202-164 Drake PT but its not the same colour code as the Dagnall that was in my 1987x. Heres a pic of my ''new'' PT. I want to bypass the voltage selector and just wire it up for 120 vac. I can just put the brown(120V) wire directly on the AC switch on the lug beside the blue(common) l...

Hey Phil. I lifted the ct of the 2 red wires and measured across the the 2 lugs where the red wires are connected on the standby and I have 21 VAC.

O.K. I took the old mains fuse out and hooked up a light bulb to the mains fuse holder. I disconected the heaters and its center tap. I left the standby in the open position since the red wires are fed to there before they go to the rectifier diodes.

The light is still bright. PT fried?

I resoldered and tied up the sheilded cable going to the grid resistors from my PPIMV. I moved and tied up my NFB wire that was crossing the OT primary wires. I then changed my 47p PI cap for a 100p. This enabled me to even put a 4700p bright cap on VolI (no bright cap before) which adds a nice spar...

Fixed!

I have this annoying mosquito like buzz on top of the notes. Its a highend shrill thats really irritating when I play. What causes this?

Heres a pic.

[IMG:800:600]http://i46.photobucket.com/albums/f144/ ... ead001.jpg[/img]

Phil, I was talking about the secondary wires on the PT. I have red, black and brown which goes to the heaters(red and black) pins 2 and 7 respectively and the brown which goes to the ground. Then I have 3 smaller wires(2 red which go to the standby and another black that goes to ground)

As soon as I hit the standby, it goes through the rectifier, comes out DC and into the first filter cap and then we would be dealing with the HT fuse I guess. PT secondary, I disconnect brown wire which is grounded(CT) and the 2 heater filaments(black and red) and I leave 2 red wires going to the st...

I got a light bulb and I'm going to jump the mains fuse holder with it without the fuse. I'll disconnect the secondary wires and fire it up and see how bright the light shines. If its still bright with the secondary unhooked, I'll just start unhooking things until the light dims. What would be a goo...

If it is shorted, it will blow fuses. Is there some other reason that suggests it is the PT? Before jumping off on a bunch of unnecessary work, have you tried to power up the amp with all the tubes pulled out? For the most part, this "unloads" the transformer, except for maybe the pilot light. Assu...

I think my power tranny is blown. The wires going to the mains selector is the primary and they are black, orange and yellow. Theres another yellow wire on the center on the selector. If I measure the resistance from any of the wires to ground I get nothing. From black to yellow 6.6ohms from black t...

Thanks especially to you Firestorm for taking the time to help me. It sounds killer! Smooth, twangy and round. I think I'll be putting my Marshalls away for awhile.

FIXED!!!! YES!!!!!!!!! Thanks for putting up with me guys. I got assbackwards for a while but got on the right track. There was another plate resistor in the preamp section with a hairline fracture because it read fine but he was the badass. New powersockets, powersupply caps, 2 plate resistors, 2 c...