Re: Philips 25kv EHT unit.
Yesterday afternoon a little progress was made on the 131. The EHT unit was refitted together with the main chassis and the very heavy power supply.
Switching on was quite boring, no bangs as such with the H.T. rail rising to it's correct potential. No line whistle could be heard, just the drone of the EHT oscillator.
Increasing the brightness produced nothing on the screen suggesting that the tube protection circuit had come into operation due to the failed timebase/timebases. The line output valve had H.T. on its anode and was quite warm so I guess it is not being driven.
No familiar buzz could be detected from the frame department. It may be a common cause. [So is snow in summer]
Switching off produced the classic fading 'blob' confirming my thoughts.
It was decided to remove the chassis and the CRT unit minus the optical box to my familiar workshop where detailed fault finding can continue with the aid of a scope.
The pictures show the units. On the left the heavy power supply. Left front, control panel with on/off switch. Centre, main chassis underside. To the right, EHT unit and CRT assembly including scan coils and focus coil.
I nice quiet evening should sort it out. Probably......Regards, John.
PS That workbench looks cluttered..It is 8' X 4' I need a bigger one.
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