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

Heatercathodeshort · 28th Feb 2015, 4:17 pm

I have just played the National Anthem on a 78 RPM record given to me by the manager of the Regal Wimbledon when it closed years ago..

Make sure the interfearance limiter is 'off '. Replace waxies in frame output stage with particular reference to C43 .1uf C41 .02uf C44 .0082 [weird value, use nearest] C45 .015uf C46 .1uf and finally the cathode bias capacitor, C56 160uf. It may be O/C but I suspect it's the miss matched transformer. Try reducing the value of the bias resistor to 100ohms [R25] then experiment with various sound output/frame output transformers till you get something acceptable. It should be 100% linear.
Stick to Plessey chassis and TV22's Mark. They can be repaired in a blacked out room...Great news! John.

28th Feb 2015, 4:17 pm	#96
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Marconiphone VRC74DA I have just played the National Anthem on a 78 RPM record given to me by the manager of the Regal Wimbledon when it closed years ago.. Make sure the interfearance limiter is 'off '. Replace waxies in frame output stage with particular reference to C43 .1uf C41 .02uf C44 .0082 [weird value, use nearest] C45 .015uf C46 .1uf and finally the cathode bias capacitor, C56 160uf. It may be O/C but I suspect it's the miss matched transformer. Try reducing the value of the bias resistor to 100ohms [R25] then experiment with various sound output/frame output transformers till you get something acceptable. It should be 100% linear. Stick to Plessey chassis and TV22's Mark. They can be repaired in a blacked out room...Great news! John.