Welcome To the Hoffman Amplifiers Forum

September 07, 2025, 12:01:16 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Marshall 100w plexi...not my build, just my problem  (Read 2044 times)

0 Members and 1 Guest are viewing this topic.

Offline Heavychills

  • Level 1
  • *
  • Posts: 2
  • I love Tube amps
Hoffman Amps Forum image
Marshall 100w plexi...not my build, just my problem
« on: August 27, 2017, 03:07:32 am »
I bought a Peavey butcher off of Craigslist last week that was turning on but not making sound.  I got it home and immediately tested all the tubes.   All the tubes we're working fine.  So I opened the amp up only to find the entire thing had been gutted out and rebuilt.  Judging by the Meecury Magnetic's transformers and choke that were installed this was some sort of personal build Similiar to a 100w Marshall plexi.  So I'm trouble shooting around the amp trying to figure what could possibly be wrong and I notice the OT CT and one of the choke wires are disconnected.   I also noticed the B+ fuse is grounded but has nothing else connected to it.  So I tried connecting the OT CT and the choke to the B+ fuse but no sound still.  I've got some other ideas I'm going to try but I'd like to hear some advice on how to trouble shoot this.  Sorry my picture files seem to be to large to attach.

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: Marshall 100w plexi...not my build, just my problem
« Reply #1 on: August 27, 2017, 06:10:16 am »
Draw a schematic.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline tubenit

  • Global Moderator
  • Level 5
  • ******
  • Posts: 10274
  • Life is a daring adventure or nothing at all!
Hoffman Amps Forum image
Re: Marshall 100w plexi...not my build, just my problem
« Reply #2 on: August 27, 2017, 06:49:26 am »
Agree with Sluckey,  draw a schematic for us to see, please.  Look at the Marshall schematics as a starting point since you seem to think this may be a Marshallish type rebuild?

http://el34world.com/charts/Schematics/files/marshall/Marshall_1987%20JMP%20Lead%2050watt%20EL34.gif

http://el34world.com/charts/Schematics/files/marshall/Marshall_50w_2204s.pdf

http://el34world.com/charts/Schematics/files/marshall/Marshall_jtm45-readable.pdf

http://el34world.com/charts/Schematics/files/marshall/Marshall_Schematics.htm

IF you have Windows PAINT,  you can open your pictures up and then "resize" them to get them within the proper size for posting.  You simply "resize" them to maybe 45% horizontally and 45% vertically and resave them. 

Then click on the saved photo to see what size it is now.  We can be more helpful to you if we have a schematic and photos to work with.

IF you got the amp at a good price and it has Mercury Magnetics transformers in it and you can get it working well .......... you may end up with a remarkably good buy?

With respect, Tubenit

 


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