On Aug 29, 11:57 am, "Peter Andersen"
wrote:
I have to NAD T762 on the table. Both with burned out (shorted) 5,1V
zenerdiodes (D718).

I have replaces them with a new 5W type instead of the original 2W.

But the diodes is getting extremely hot and I can't figure out if this is ok
(like the way it was designed). They are sitting directly in series with a
7812 from a 22V DC supply. The thought behind the design must bee to divide
the power loss between the zenerdiode and the 7812.

The amplifier is working, but I don't like those hot zeners!

Is there anybody out there that have worked on a NAD T762?

Peter

*Shorted* Zeners? Are you sure? Usually they fail open.

Betcha you have a shorted driver transistor, possibly even a shorted
output transistor. What other tests have you done?

Peter Wieck
Wyncote, PA