Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Tubes and Hybrids => Topic started by: solidstate2199 on May 20, 2018, 07:45:20 AM

Title: Cooked Super Amplifier
Post by: solidstate2199 on May 20, 2018, 07:45:20 AM
Bought an old Superlead Style Amp, its not here yet.

One burned out EL34 Socket and what looks like the
negative feedback resistor is shot, plus collateral
to the surrounding parts.


There is a cable coming from the 16ohm speaker jack going
to that resistor so i guess it is the 100k seen on the schematic.

Can i suspect output transformer damage?

I make better pics when i have it here.
(http://www.bilder-upload.eu/thumb/be0ee7-1526816082.jpg) (http://www.bilder-upload.eu/show.php?file=be0ee7-1526816082.jpg)

schematic
https://drtube.com/schematics/londoncity/dea100-early.gif
Title: Re: Cooked Super Amplifier
Post by: g1 on May 22, 2018, 12:21:58 PM
A burnt feedback resistor is pretty rare.  The only thing I can think would cause it is the same thing that would toast the output tube socket, running signal with no load connected.
So yes, you need to be somewhat suspicious of a damaged OT.