Welcome To the Hoffman Amplifiers Forum

September 08, 2025, 05:56:47 am
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Blues Junior Conversion: International Power Transformer question  (Read 1952 times)

0 Members and 1 Guest are viewing this topic.

Offline deaftone

  • Level 1
  • *
  • Posts: 2
  • I love Tube amps
Hello guys,

First of all thank you for the opportunity to improve my Blues Junior. Can't wait to fire it up!

I was looking for a similar topics but didn't find anything related.

My BJ Conversion is almost finished and the only unclear issue to me is the connection of the original international power transformer. Since this business might be very dangerous i have that someone could verify what i understand from the BJ schematics.

I don't have an original board which makes thing a bit difficult to me. So... The Export Power transformers has a lot of input wires and options .. 100, 120, 230 and 240 volt.

From the original BJ schematics (2005 model) for 240 V option i understand the following:

1. Violet wire goes to the switch (fuse side)
2. Black wire goes to the switch
3. Blk/grn and blk/yel have to be connected (according to the connection between points P9 and P10 on the board)
4. The rest of the input wires has to be untouched and isolated.

All these are marked on the attached screenshot.

I will be very grateful if someone can approve or disapprove it. Thank you :)

Anton.

Offline PRR

  • Level 5
  • *******
  • Posts: 17082
  • Maine USA
Hoffman Amps Forum image
Re: Blues Junior Conversion: International Power Transformer question
« Reply #1 on: April 26, 2017, 07:10:10 pm »
Welcome.

Your mark-up appears correct for 240V.

Bonus if you have a lamp-limiter for initial start-up. If something IS wrong, it is better to see the lamp glowing brightly than the transformer glowing brightly.

Offline deaftone

  • Level 1
  • *
  • Posts: 2
  • I love Tube amps
Hoffman Amps Forum image
Re: Blues Junior Conversion: International Power Transformer question
« Reply #2 on: April 27, 2017, 01:13:27 am »
Thank you!

I will definitely use the current limiting lamp before i start it up.

Best

Anton

 


Choose a link from the
Hoffman Amplifiers parts catalog
Mobile Device
Catalog Link
Yard Sale
Discontinued
Misc. Hardware
What's New Board Building
 Parts
Amp trim
Handles
Lamps
Diodes
Hoffman Turret
 Boards
Channel
Switching
Resistors Fender Eyelet
 Boards
Screws/Nuts
Washers
Jacks/Plugs
Connectors
Misc Eyelet
Boards
Tools
Capacitors Custom Boards
Tubes
Valves
Pots
Knobs
Fuses/Cords Chassis
Tube
Sockets
Switches Wire
Cable


Handy Links
Tube Amp Library
Tube Amp
Schematics library
Design a custom Eyelet or
Turret Board
DIY Layout Creator
File analyzer program
DIY Layout Creator
File library
Transformer Wiring
Diagrams
Hoffmanamps
Facebook page
Hoffman Amplifiers
Discount Program


password