Probably HV shut down ( HVSD) is getting triggered. Some reasons are
1) the HVSD circuit is bad
2) too much HV
3) heavy load on Horz out or HV.
Its probably a Panasonic chassis & they were known for bad flybacks.
What do you have for test equipment ?? You need at least a good
meter & a variac ( or dim bulb set up ) unless you get real lucky.
BTW do you hear sound before it shuts down ?
73 Zeno
LFOD !