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Heatercathodeshort · 20th Jun 2021, 8:47 am

That is an unusual one. The picture on this one is locked by the time the line timebase has 3/4 scanned the tube. It's a quick warm up and it has the usual heater thermistor. It was shorted out on later versions to speed up warm up time but I think the initial surge was the cause of the odd O/C CRT heater.

It may be worth checking the values of the hold controls themselves. They can drift up in value and become unstable. The flywheel sync lock on all Thorn receivers including this one is usually 100%. John.

20th Jun 2021, 8:47 am	#6
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Ferguson 3629 11" 900 series. 1964/5 That is an unusual one. The picture on this one is locked by the time the line timebase has 3/4 scanned the tube. It's a quick warm up and it has the usual heater thermistor. It was shorted out on later versions to speed up warm up time but I think the initial surge was the cause of the odd O/C CRT heater. It may be worth checking the values of the hold controls themselves. They can drift up in value and become unstable. The flywheel sync lock on all Thorn receivers including this one is usually 100%. John.