PHILIPS 170 CHASSIS

There’s no line hold on 625 lines, though 405 -line operation
is correct. Until recently I was able to cure this trouble by
switching to 405 lines and then back, but this no longer
works.
There are two ECC82 valves (V401/2) in the line
generator circuit. The most common cause of this trouble is
simply that one or both has aged. There are several resistors
that can increase in value however in this area, and we
suggest you check R420 (470k52), R405 (220k 2) and R417
(430k52). Also check the 625 -line hold control R416 which
may have developed a break in its track, and the operation
of the system switch.