Welcome To the Hoffman Amplifiers Forum

September 06, 2025, 01:45:44 pm
guest image
Welcome, Guest. Please login or register.
-User Name
-Password



Hoffman Amps Forum image Author Topic: Fender HRD III - No Reverb but Tank and RCA cables are OK.  (Read 1935 times)

0 Members and 1 Guest are viewing this topic.

Offline spunko

  • Level 2
  • **
  • Posts: 128
  • I love Tube amps
Hoffman Amps Forum image
Fender HRD III - No Reverb but Tank and RCA cables are OK.
« on: July 28, 2024, 05:38:26 pm »
Hello friends.
I got this amp cheap w/o speaker, and with all the common problems, bad IC caps, bad traces, bad solder joints, and no reverb. All is good and working now except for the reverb, first time with this problem.
Tested the tank with my multimeter and both ends read ok, I have another tank to compare and test. Also both RCA cables test OK for continuity.

If I hit the tank with my hand it sounds, if I touch with my finger the tip of the RCA cable (wht - from reverb to amp) it HUMs, so I guess U2 (4560) is ok.
I don't have a scope, but I have a home made signal tracer and there is no signal present on the tip of the RCA that goes into the tank imput (red - from amp to reverb). No signal on pin 1 U2A (TP20), no signal on TP19, nor TP13.
Where should I start tracing the signal? Could U2 (4560) be bad?
This one is new for me  :help:

Thak you very much!

Offline AlNewman

  • Level 3
  • ***
  • Posts: 852
  • I love Tube amps
Hoffman Amps Forum image
Re: Fender HRD III - No Reverb but Tank and RCA cables are OK.
« Reply #1 on: July 28, 2024, 05:53:55 pm »
Does it work with the footswitch plugged in?

Offline Latole

  • Level 4
  • *****
  • Posts: 2522
Hoffman Amps Forum image
Re: Fender HRD III - No Reverb but Tank and RCA cables are OK.
« Reply #2 on: July 29, 2024, 03:11:55 am »
If voltages are good on U2, yes, it could be bad.
And if printed circuit ( or connector ?) are good.

To my use a scope will be more reliable to see

« Last Edit: July 30, 2024, 10:56:04 am by Latole »

Offline spunko

  • Level 2
  • **
  • Posts: 128
  • I love Tube amps
Hoffman Amps Forum image
Re: Fender HRD III - No Reverb but Tank and RCA cables are OK.
« Reply #3 on: July 30, 2024, 09:56:45 am »
Yay! It is fixed. U2 (4560) was the problem.
Thanks for the help!  :icon_biggrin:

Offline Latole

  • Level 4
  • *****
  • Posts: 2522
Hoffman Amps Forum image
Re: Fender HRD III - No Reverb but Tank and RCA cables are OK.
« Reply #4 on: July 30, 2024, 10:56:40 am »
Yay! It is fixed. U2 (4560) was the problem.
Thanks for the help!  :icon_biggrin:

Congrat, you are a good tech !

 


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