Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 12:48:53 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Re-capping a Fender Studio bass  (Read 2887 times)

0 Members and 1 Guest are viewing this topic.

Offline pbman1953

  • Level 3
  • ***
  • Posts: 1091
Hoffman Amps Forum image
Re-capping a Fender Studio bass
« on: January 08, 2024, 11:21:31 am »
HI All,


Happy New Year!


My next venture would to re-cap a Fender Studio Bass. Here's a link to the proposed company that sells kits for the amp-






https://www.amprepairparts.com/fendercapkits.htm


Look for the Part #FCK-19

This kit is for a Super Twin which is similar but not exact. I think that I'd have to use a radial-  750uf/ 3v. Axial's are tough to find in a small voltage


I was wondering if any other parts needed a tweak, value wise. Plus, if you would stay, with the shown 1.5 k grid resistors , or change that value.




Thanks!



 
« Last Edit: January 10, 2024, 09:40:23 am by pbman1953 »

Offline Latole

  • Level 4
  • *****
  • Posts: 2522
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #1 on: January 08, 2024, 12:44:11 pm »
No need to replace 1,5 k grid resistors . Why ?
Read 470 ohms grid resistor and replace if needed.
Check fuse to be sure it is the right one. Too many people put more powerful fuse over years .
Amp need 6 1/4 normal/ fast blow fuse.

All you need are main and bias power supply  filter caps . Forget other caps or resitors. Values are not for this amp and amp may not need them.
You can buy from many store like Tube Depot, Antique electronics

From amprepairparts ; look here; https://www.amprepairparts.com/caps.htm#ftcap

3 F&T 22uF-500V (Main Filters - Decoupling)
2 F&T 220uF-300V (Main Filters)
2 F&T 100uF-100V (Bias Filters)
« Last Edit: January 08, 2024, 12:52:25 pm by Latole »

Offline pbman1953

  • Level 3
  • ***
  • Posts: 1091
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #2 on: January 08, 2024, 12:50:52 pm »
Perfect, thank you!

Offline Latole

  • Level 4
  • *****
  • Posts: 2522
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #3 on: January 08, 2024, 02:08:54 pm »
You know you must  put positive + side of the bias filter cap to ground.


Offline pbman1953

  • Level 3
  • ***
  • Posts: 1091
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #4 on: January 08, 2024, 02:11:35 pm »
yes,thanks!

Offline WimWalther

  • Level 2
  • **
  • Posts: 337
  • If I can't fix it I'll fix it so it can't be fixed
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #5 on: January 10, 2024, 12:55:09 am »
750uf/ 3v. Axial's ae tough to find in a small voltage.

But really, you can use about any cap that fits,  from 3V to.. maybe 50V?

Offline d95err

  • Level 2
  • **
  • Posts: 244
  • I love Tube amps
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #6 on: January 10, 2024, 02:17:02 am »
750uf/ 3v. Axial's ae tough to find in a small voltage.

In addition to this, 750uF is a very unusual value. Anything from 470 to 1000 uF should be fine.

But really, you can use about any cap that fits,  from 3V to.. maybe 50V?

Offline Latole

  • Level 4
  • *****
  • Posts: 2522
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #7 on: January 10, 2024, 03:33:37 am »
HI All,


  750uf/ 3v. Axial's ae tough to find in a small voltage




MouserElectronic have many in axial from 8 to 100volts
Or Digikey ?

https://www.mouser.ca/c/passive-components/capacitors/aluminum-electrolytic-capacitors/?capacitance=750%20uF

One of them;



Offline pbman1953

  • Level 3
  • ***
  • Posts: 1091
Hoffman Amps Forum image
Re: Re-capping a Fender Studio bass
« Reply #8 on: January 10, 2024, 07:31:51 am »
Thanks guys, I saw the radial at Mouser.




Thanks!

 


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