FDP Home Page / FDP Forum / FAQ's

The FDP is made possible by the following companies and individual members like you.
Please use the links below to show them we value their sponsorship.

Apex Tube Matching

Guitar Center

Antique Electronics Supply

Jensen Loudspeakers

Amplified Parts




Musician's Friend

Yellowjackets Tube Converters

WD Music

* God bless America and our men and women in uniform *

* Illegitimi non carborundum! *

If you benefit and learn from the FDP and enjoy our site, please help support us and become a Contributing Member or make a Donation today! The FDP counts on YOU to help keep the site going with an annual contribution. It's quick and easy with PayPal. Please do it TODAY!

Chris Greene, Host & Founder



Find musicians
in your area!
  Search the Forums  

FDP Forum / Amp Mods, Repairs, and Projects / Fuse blowing after about 5 minutes

Previous 20 Messages  
Contributing Member

Boston Area

Oct 7th, 2017 08:50 AM   Edit   Profile   Print Topic   Search Topic

Yes - reflow. Something's not connected. Also, if you can, lift the bias circuit board from the chassis to see if something's shorting down there.

(This message was last edited by JJuran at 10:56 AM, Oct 7th, 2017)

Contributing Member

United States

Vance Erickson
Oct 7th, 2017 11:00 AM   Edit   Profile   Print Topic   Search Topic

OK, fixed it.

I was getting ready to reflow the joint between the bias resistor and the bias diode when I saw that the leg of the resistor was lifted away from the solder! Once I got the solder off I saw that the leg of the diode was just lying on the metal grommet in the bias board, not in it.

So clearly I did a very bad job when I soldered those components in a couple of years ago. I don't mind telling on myself if it helps someone else.

In case it interests anyone, the fuse first blew when I was trying out the trick of bridging the reverb input and output with a cable with a 330k resistor soldered in. Sounded great for about five minutes (lots of extra gain controlled by the Reverb knob), then the fuse blew. I thought my "mod" had caused the problem, but it was really just moving the amp around to make the connections in the back. The wonky speaker /attenuator connection was another red herring. Never assume.

The power tubes are fine, btw.

(This message was last edited by vanceen25 at 01:02 PM, Oct 7th, 2017)



Oct 7th, 2017 01:05 PM   Edit   Profile   Print Topic   Search Topic

Good find; it's amazing how lucky you can be with this sort of stuff sometimes, but eventually luck tends to run out!



Bobby Roadrunner
Dec 24th, 2017 06:57 AM   Edit   Profile   Print Topic   Search Topic

I had the same issue in my 67 Super Reverb, mine turned out to be the original Mullard GZ34 was slightly bad. I replaced it with a new one, the problem went away.

Previous 20 Messages  

FDP Forum / Amp Mods, Repairs, and Projects / Fuse blowing after about 5 minutes

Reply to this Topic
Display my email address             Lost your password?
Your Message:
Link Address (URL):
Link Title:

Moderators: Chris Greene  Iron Man  reverendrob  

FDP, LLC Privacy Policy: Your real name, username, and email
are held in confidence and not disclosed to any third parties, sold, or
used for anything other than FDP Forum registration unless you specifically authorize disclosure.

Internet Application Development

Copyright © 1999-2018 Fender Discussion Page, LLC   All Rights Reserved