OK this is probably one of the nastiest power supplies ever used
in a TV. Only the Sony double SG613 may be worse.
You need to find if the SD is from a fail in either the TV or SD.
Looking at the pix its near perfect so odds are its a SD problem.
I assume the arcing is the SMPS making the TIC TIC.
BE AWARE this set has 2 major grounds !! You want to use the HOT
ground ( blank triangles ) for voltage measurements.
Anyhows you may want to use freeze mist on it & see if you can knock it out.
Start at Q492 v& 494. Also Z402. Also any 'litics in the area. Just a few parts at a time. If you hit it put freeze on a Q-tip & touch the suspect.
73 Zeno
LFOD !