Every three to four months this set blows the chopper
device Q603 on the power supply board and the line output
device Q510 on the timebase board. The set works normally
after replacing these devices (type SG6533), then the same
thing happens three-four months later.
This is a nasty, expensive habit your set has acquired!
We have it on good authority that the sync/timebase oscillator i.c. IC501 (CX104A) or the main smoothing electrolytic C606 (120µF) can be responsible, and have also
known it to be due to the line flyback tuning capacitor C542