Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Tiny_Daddy on November 25, 2010, 08:03:16 am

Title: Fried Gibson Hawk
Post by: Tiny_Daddy on November 25, 2010, 08:03:16 am

It has happened again. Someone got out an amp that had been in a closet since 1963 and tried to play it. One filter cap burst and the power transformer primary has shorted. This is the nice one with 5 preamp tubes and 7591 output tubes. Chassis is marked GA 25 RVT but does not match with the schematic on Doug's list (no tube rectifier, etc.) I plan to install Hammond 272FX unless someone has a better suggestion?

Title: Re: Fried Gibson Hawk
Post by: FYL on November 25, 2010, 08:34:47 am

Here's the schemo of the 7591 version:

(http://i50.photobucket.com/albums/f308/artnor/Hawk_Schematic.jpg)

Poor quality, but somewhat usable.

Title: Re: Fried Gibson Hawk
Post by: Tiny_Daddy on November 25, 2010, 09:06:29 am

Thanks FYL. On second thought since there is no rectifier delay or voltage drop I may use the lower-voltage Hammond 270FX to avoid no-load over-voltage when first switched on. It seems to be about the same core size and maybe I can install the original end bells.