Nigel Goodwin said:
I would check R13, R33 and C13.
R33 = 820K = OK.
C13 = 47uF/50V = OK (LC tester Velleman DVM6243, scale 200uF)
Cap is OK, but I don't know about ESR...)
You suggested to check R13 also. But R13 does not exist on the PCB!
Looking for R13, to my surprise I found two references R14:
-R14=10Kohm between pins 6-9 of hybride (test=OK)
-R14=200K/2W = pin8-hybride/+320Vbridge, unfortunately, test=OK!
May be one of these is R13. May be is twice 14 to avoid 13!!!
(see detail3.jpg)
Of course, pin8/hybride take the start voltage via R14-200K/2W (!)
May be fault hybride at pin 8...
What can I do?
R13... suspect, C13... suspect. Too much 13 !!!