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SiriusHardware · 22nd Apr 2020, 10:23 am

The ZX81 doesn't have the fairly complex circuitry needed to generate a colour signal for the set to 'see', but in the absence of a colour carrier from the source, a circuit called a 'colour killer' should really come into play on the TV.

Maybe this particular TV is a little bit taken aback when confronted with a monochrome source. (Being an LCD set, it will have been made many, many years after mono broadcast transmissions and other monochrome-only sources were common).

You could try letting the fault clear and then try cooling various things including the regulator, electrolytic capacitors, etc, to see if the colour noise comes back when you do that. Don't blast the electrolytics too hard, they contain liquid inside which needs to remain liquid in order for them to work...

22nd Apr 2020, 10:23 am	#271
SiriusHardware Dekatron Join Date: Aug 2011 Location: Newcastle, Tyne and Wear, UK. Posts: 11,560	Re: Zx81 The ZX81 doesn't have the fairly complex circuitry needed to generate a colour signal for the set to 'see', but in the absence of a colour carrier from the source, a circuit called a 'colour killer' should really come into play on the TV. Maybe this particular TV is a little bit taken aback when confronted with a monochrome source. (Being an LCD set, it will have been made many, many years after mono broadcast transmissions and other monochrome-only sources were common). You could try letting the fault clear and then try cooling various things including the regulator, electrolytic capacitors, etc, to see if the colour noise comes back when you do that. Don't blast the electrolytics too hard, they contain liquid inside which needs to remain liquid in order for them to work...