GEC BT320 line foldover - UK Vintage Radio Repair and Restoration Discussion Forum

Restoration73 · 21st Oct 2014, 4:35 pm

After recapping, this works well but I notice a slight fold over on the left
altered by the hold control - line sync is excellent though
Any tips on this

Boom · 21st Oct 2014, 6:01 pm

I'm sure someone will tell you if I am wrong but think that this is normal. Just bring the width in very slightly and set the line hold to get rid of the foldover then open the width back up.

Heatercathodeshort · 21st Oct 2014, 6:11 pm

I would agree with Dave. This is not a flywheel sync model and it may well be that the sync separator may not like the generated signal compared with genuine off air. It looks excellent in every way as these GEC receivers always do! John

Restoration73 · 21st Oct 2014, 6:15 pm

Looking at the circuit, the line osc connects to the sync sep anode via a 4.7pF with a
68p to ground so there can't be much to sort. It is not the "false lock" sometimes seen.
Of course, had it used flywheel sync this problem wouldn't arise.

Agreed John, this set has all the original valves and crt too.

21st Oct 2014, 4:35 pm	#1
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	GEC BT320 line foldover After recapping, this works well but I notice a slight fold over on the left altered by the hold control - line sync is excellent though Any tips on this Attached Thumbnails

21st Oct 2014, 6:01 pm	#2
Boom Retired Dormant Member Join Date: Jan 2007 Location: Westbury, Wiltshire, UK. Posts: 2,451	Re: GEC BT320 line foldover I'm sure someone will tell you if I am wrong but think that this is normal. Just bring the width in very slightly and set the line hold to get rid of the foldover then open the width back up.

21st Oct 2014, 6:11 pm	#3
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: GEC BT320 line foldover I would agree with Dave. This is not a flywheel sync model and it may well be that the sync separator may not like the generated signal compared with genuine off air. It looks excellent in every way as these GEC receivers always do! John

21st Oct 2014, 6:15 pm	#4
Restoration73 Nonode Join Date: Jun 2013 Location: Surbiton, SW London, UK. Posts: 2,801	Re: GEC BT320 line foldover Looking at the circuit, the line osc connects to the sync sep anode via a 4.7pF with a 68p to ground so there can't be much to sort. It is not the "false lock" sometimes seen. Of course, had it used flywheel sync this problem wouldn't arise. Agreed John, this set has all the original valves and crt too.