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Heatercathodeshort · 12th May 2014, 6:43 pm

This does not make sense. If the EY86 is lit, there must be EHT at the anode end from the transformer overwind. If not this can only be due to an open circuit/break of some length as small break would result in sparking and smoke due to arc over. How are you checking the DC EHT? You need to short one end of the screwdriver to chassis and bring it very close or actually touch the CRT connector, the metal bit of course. It should crack over but will do no harm. The AC end can be checked by simply dragging a screwdriver tip over the feed end of the EHT overwind [EY86 top cap]. There is no need to earth the screwdriver for this test. Replace all the wax caps in the line oscillator and output stage before delving too deep. Tick them off the circuit as you work as I think there are a couple UNDER the tag boards. I wish I had that chassis on my bench! Interesting symptoms. Regards, John.

12th May 2014, 6:43 pm	#40
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Is it a Bush TUG.68 ? This does not make sense. If the EY86 is lit, there must be EHT at the anode end from the transformer overwind. If not this can only be due to an open circuit/break of some length as small break would result in sparking and smoke due to arc over. How are you checking the DC EHT? You need to short one end of the screwdriver to chassis and bring it very close or actually touch the CRT connector, the metal bit of course. It should crack over but will do no harm. The AC end can be checked by simply dragging a screwdriver tip over the feed end of the EHT overwind [EY86 top cap]. There is no need to earth the screwdriver for this test. Replace all the wax caps in the line oscillator and output stage before delving too deep. Tick them off the circuit as you work as I think there are a couple UNDER the tag boards. I wish I had that chassis on my bench! Interesting symptoms. Regards, John.