Dave Plowman (News) wrote:
Got an 'interesting' fault on an ancient Linsey Hood amp. Switch on a
light etc, and sometimes *one* channel bursts into loud mains hum - but
carries on working. And the output transistors get very hot. It's not
normally susceptible to mains born interference - so any guesses before I
rip it apart?

Both channels seem to match ok before this happens.

Which JLH amp?
His book on electronics is still available in many public libraries
with details of the 75 watt class AB and the 15? watt class A amps,
and of course the internet has plenty of circuit diagrams.
The 75w amp needs regular servicing to adjust the bias current and output offset voltage,
and that unbiased electrolytic at the bottom of the feedback ladder could be a problem.

Other than that, I have no idea. You could try a Russ Andrews mains cable. :-)

--
Eiron.