Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: lucasdmusic on September 19, 2017, 02:37:54 pm
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Howdy,
Been slowly chipping away at a build of an AB763 Vibroverb using Doug's board. I'm using Classic Tone for my iron, specifically the 40-18001 for OT and 40-18094 PT. This is my first build with Classic Tone transformers and my first time going for a build with just a layout and a schematic. So far so good, but I've reached a bit of an impasse. With everything mounted and board squared away, its about time to get the PT hooked up, but I am a bit confused as to how to go about that.
I understand that both of the 5V taps go to the rectifier but I was wondering if someone might help me decipher the high voltage (plate?) windings as I am having trouble making sense of Classic Tone's transformer wiring diagram given Doug's hookup instructions.
Also the heaters, what is to be done with the third wire, as there is GRN, GRN/YEL, and GRN?
How does one hook up the primary side?
Overall I suppose I have having trouble determining which leads will be used versus those that will be heat-shrunk and tucked away.
:dontknow:
I've attached the transformer wiring diagram for the PT.
Thanks!!
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I looked at the Vibroverb AB763 schematic and it calls for 355-0-355 into a GZ 34 rectifier, so you want to use the 2 - RED wires as your high voltage connection to your rectifier.
Use the Red/Yellow wire as your secondary center tap (which gets grounded)
Use the Red/Green wire for your bias supply
Isolate and tape off the 2 - Red/White wires (not used)
As for the Green/Green-Yellow/Green, you would normally ground the Green/Yellow wire because it is the center tap for the filaments.
Doug shows 2- 100 ohm resistors for an artificial center tap (if you didn't have a Green/Yellow wire - some transformers don't)
You can either omit the resistors from Doug's design or use them and tape off the Green/Yellow.
My preference is to use the wire and omit the resistors.
On the primary side, you have to choose what input voltage you will be using...
I will assume you have and want to connect for 120VAC
Connect the BLACK and BROWN wires and use that as your BLACK wire
Connect the BLK/WHITE and BROWN/WHITE wires together and use that as your WHITE wire
*Also connect the ORANGE wire to a ground point (usually using the transformer mounting bolt)
Enjoy your build!