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Argus25 · 25th May 2018, 5:59 am

It is always possible that there is an intermittent problem in the LOPTY, but I think this is far less likely than a problem with the capacitors associated with the circuit:

On my trader sheet, I would suspect initially C32, the electroltyic 2uF boost capacitor connected between the HT and the linearity control. Also replace C37 the 2uF yoke coupling cap , another electrolytic. I would replace both of those with non electrolytic poly caps, the Solen Fast 400 or 630V ones work well.

Then, also in this circuit just the smallest amount of leakage in C29, the G1 grid coupling cap to the PL38, grossly upsets the circuit so make sure that is a new part, and after that, make sure C33 a 0.2uF the capacitor across the lin coil is renewed and also the tuning capacitor C34 on the lopty secondary is new.

Check for other things like a bad screen or cathode connection on the PL38 or a problem with the damper rectifier. All that doesn't exclude everything but its a start. At least if those parts are all new you can look elsewhere for the cause of the fault if it recurs. These parts may already be new ?

25th May 2018, 5:59 am	#15
Argus25 No Longer a Member Join Date: Oct 2016 Location: Maroochydore, Queensland, Australia. Posts: 2,679	Re: Bush TV22 flyback pulse It is always possible that there is an intermittent problem in the LOPTY, but I think this is far less likely than a problem with the capacitors associated with the circuit: On my trader sheet, I would suspect initially C32, the electroltyic 2uF boost capacitor connected between the HT and the linearity control. Also replace C37 the 2uF yoke coupling cap , another electrolytic. I would replace both of those with non electrolytic poly caps, the Solen Fast 400 or 630V ones work well. Then, also in this circuit just the smallest amount of leakage in C29, the G1 grid coupling cap to the PL38, grossly upsets the circuit so make sure that is a new part, and after that, make sure C33 a 0.2uF the capacitor across the lin coil is renewed and also the tuning capacitor C34 on the lopty secondary is new. Check for other things like a bad screen or cathode connection on the PL38 or a problem with the damper rectifier. All that doesn't exclude everything but its a start. At least if those parts are all new you can look elsewhere for the cause of the fault if it recurs. These parts may already be new ?