|
Posted to sci.electronics.repair
|
|
|
Engl valve amp disaster
Gareth Magennis wrote:
The only schematic I could find is the same one Engl sent me, and is not the
right one for this particular model, but here it is for reference.
https://music-electronics-forum.com/...ad.php?t=46947
Anyway, look at the output stage.
There are 2 BY509 diodes on the Anodes of the 6L6 valves, going to the
standby switch and then to ground.
Only the amp I have here isn't quite like that.
THIS one has the 2 BY509 diodes connected to the HEATER circuit, pin 2, on
the output valves.
The diodes are connected to pins 2 and 3 of the output valves.
The standby switch connects all cathodes to ground, but is not connected to
either diode.
Now, I found one of these diodes is shorted.
Bummer.
Meaning you get HT fed to all the heaters in the amp.
Double bummer is that the heater winding has a 250 Ohm hum balance pot
across it, connected to ground, the heater winding is otherwise in the air.
|