I haven't worked on one of these or seen the circuit
diagram for one.
However from experience I would suggest you start at the SCR
and work through the control circuitry.
When an SSR
melts down it can take out anything connected to the gate
, because the gate circuit
is normally low current
compared to the main terminals. And if your SCR
got hot enough to melt then I would expect collateral damage.
. I am not sure if these were connected from the control circuit
by a DIAC , pulse transformer
or opto- coupler
. I would compare the control circuit
of a good channel
to the faulty one and you should be able to find the faulty part(s). Did you check the PCB
for any burned tracks?
Sorry I can't be more specific but this is where I would look faced with the same situation.