N_Cook Inscribed thus:

Believed to have been making an "electrical smoke" smell but performed
faultlessly for a gig, just general smokey smell , nothing specific to
this amp, I am trying again to find out why this amp is supposed
suspect and not anything else.
During the gig the stage supply tripped out. Nothing found amiss and
powered up lights and amps and continued .

No discolourations / open Rs/ open user or 7 internal fuses etc.
Removed the Zobell R and it is .8R rather than 1.5 ohm , but I don't
think is discoloured enough to have been burning.
No disc ceramics etc between ground and live / neutral.
Filter block X2 type 375V ac across L-N marked .1uF R .46 measured
.024uF on C and 1.2K on R scale on 1KHz RLC meter. Now hacked into and
no sign of smoke or overheating inside the cladding. It lays next to
the dropper for the mains relay and slightly discoloured cladding
,one-sided externally, from that proximity probably.
Currently exploring the power amp which looks fine but in case one or
more transistors has gone open circuit and brief enough short circuit
to trip the mains trip but not any fuses .
No trace of smoke around the large mains Tx but will unbolt to check
underneath.
Any other suspects that would leve no trace?
How to find a problem , if there is not one to find?

Exploding tantalum bead cap !

--
Best Regards:
Baron.