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FERNSEH · 10th Nov 2018, 11:24 pm

Follow up to previous threads about the Cossor 54 TV receiver. Picture focus has been improved by replacing the 3.3megohm resistors R44 and R46 in the focus control bleeder chain, see attached circuit diagram. Both resistors had risen in value to 11 megohms. The original 2megohm focus control was replaced some time in the forties or fifties with a 5megohm radio volume control, it even has the on-off switch attached to it. The replacement focus control has a log law track but seems to work OK.
The correct value for R45 is according to the parts list is 2megohms.

DFWB.

10th Nov 2018, 11:24 pm	#1
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Cossor 54. Follow up to previous threads about the Cossor 54 TV receiver. Picture focus has been improved by replacing the 3.3megohm resistors R44 and R46 in the focus control bleeder chain, see attached circuit diagram. Both resistors had risen in value to 11 megohms. The original 2megohm focus control was replaced some time in the forties or fifties with a 5megohm radio volume control, it even has the on-off switch attached to it. The replacement focus control has a log law track but seems to work OK. The correct value for R45 is according to the parts list is 2megohms. DFWB. Attached Thumbnails