Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 10:00:30 am
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Magnatone 213 No Vibrato  (Read 1969 times)

0 Members and 1 Guest are viewing this topic.

Offline plexi50

  • Level 4
  • *****
  • Posts: 4649
  • Tube Tone
Hoffman Amps Forum image
Magnatone 213 No Vibrato
« on: May 04, 2024, 11:03:52 am »
I have put a new cap can in the chassis and the amp is loud and proud. I have great oscillation on the intensity and Speed pots. But no Vibrato in the signal path. I am looking at the varistors. One has 278vdc in & 160vdc out the other side. The other has 160vdc in & 48.8 vdc on the other lead. Does this sound like i have a bad varistor?

Offline plexi50

  • Level 4
  • *****
  • Posts: 4649
  • Tube Tone
Hoffman Amps Forum image
Re: Magnatone 213 No Vibrato
« Reply #1 on: May 04, 2024, 11:35:08 am »
Varistors / Caps

Offline sluckey

  • Level 5
  • *******
  • Posts: 5075
    • Sluckey Amps
Hoffman Amps Forum image
Re: Magnatone 213 No Vibrato
« Reply #2 on: May 04, 2024, 11:53:12 am »
I have great oscillation on the intensity and Speed pots.
How do you know? Exactly how did you verify that?

Quote
But no Vibrato in the signal path. I am looking at the varistors. One has 278vdc in & 160vdc out the other side. The other has 160vdc in & 48.8 vdc on the other lead. Does this sound like i have a bad varistor?
No. The voltages are different because one varistor is connected to the plate and the other varistor is connected to the cathode.
A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. Don't wait to be asked. JUST DO IT!

Offline plexi50

  • Level 4
  • *****
  • Posts: 4649
  • Tube Tone
Hoffman Amps Forum image
Re: Magnatone 213 No Vibrato
« Reply #3 on: May 04, 2024, 12:15:56 pm »
I have great oscillation on the intensity and Speed pots.
How do you know? Exactly how did you verify that?

Quote
But no Vibrato in the signal path. I am looking at the varistors. One has 278vdc in & 160vdc out the other side. The other has 160vdc in & 48.8 vdc on the other lead. Does this sound like i have a bad varistor?
No. The voltages are different because one varistor is connected to the plate and the other varistor is connected to the cathode.
I have good voltage fluctuation on the pots and the .01 Edit: 005 caps near the pot's circled in red. Turn the pots down and the fluxuating voltage goes away. YES THE ONE VARISTOR IS GOING TO THE CATHODE.. I FIGURED THAT MUCH. DAM CAPS.
« Last Edit: May 04, 2024, 02:23:26 pm by plexi50 »

Offline plexi50

  • Level 4
  • *****
  • Posts: 4649
  • Tube Tone
Hoffman Amps Forum image
Re: Magnatone 213 No Vibrato
« Reply #4 on: May 04, 2024, 12:30:57 pm »
Got these varistors 10 or more years ago if they are needed.

Offline plexi50

  • Level 4
  • *****
  • Posts: 4649
  • Tube Tone
Hoffman Amps Forum image
Re: Magnatone 213 No Vibrato
« Reply #5 on: May 04, 2024, 02:11:31 pm »
I would just replace all these old caps. But the owner would rather just have the amp working and playing nicely than change anything else. That is self defeating. The whole magic of this amp is the Vibrato! I'm not finding any leaky caps. I cant settle for this amp having no vibrato! :BangHead: :BangHead: :BangHead: :BangHead: :BangHead: :BangHead: I'm a glutton for punishment!
« Last Edit: May 04, 2024, 02:24:45 pm by plexi50 »

 


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