UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

Niechcial,Steve · 24th Oct 2017, 10:16 pm

Thanks for the comments. Just to recap-
HT, drive waveform and drive bias remain constant.
Boost falls with the width from about 650V to 560V,
All resistors and caps. (including boost cap) checked by substitution.
Boost feed to brightness and focussed networks disconnected on rare possibility something there dragging down the boost.
It really can only be the LOPT, but I would like to understand the mechanism. I've tried disconnecting the overwind input and the boost still goes down. The overwind reads correctly as per the manual when cold- 60R.

24th Oct 2017, 10:16 pm	#23
Niechcial,Steve Hexode Join Date: Jan 2007 Location: Beckenham, London, UK. Posts: 373	Re: KB VC1 width problem Thanks for the comments. Just to recap- HT, drive waveform and drive bias remain constant. Boost falls with the width from about 650V to 560V, All resistors and caps. (including boost cap) checked by substitution. Boost feed to brightness and focussed networks disconnected on rare possibility something there dragging down the boost. It really can only be the LOPT, but I would like to understand the mechanism. I've tried disconnecting the overwind input and the boost still goes down. The overwind reads correctly as per the manual when cold- 60R.