scart cable question - great picture but too much humm!

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Chandler
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scart cable question - great picture but too much humm!

Postby Chandler » Fri Apr 22, 2016 4:38 pm

I recently made up a scart cable for the ST using the below diagram and it works fine with a good clear picture

however there is a lot of "humm" when the volume is turned up (usually associated with bad earth)

can anyone advise how to removed the "humming" without messing with the wiring too much!

thanks :)

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siriushardware
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Re: scart cable question - great picture but too much humm!

Postby siriushardware » Fri Apr 22, 2016 5:11 pm

What sort of cable did you use?

It should ideally have individually screened cables (ie, each insulated wire should have its own earth screen wire surrounding it, so that each cable is screened from the cables next to it).

If you've used cable which is just a bunch of coloured insulated wires with no screen or just one overall screen then you'll get a certain amount of crosstalk (each cable will pick up some of the signal travelling down the cable next to it).

If the cable doesn't have any screening at all then it will be prone to picking up mains hum being radiated from the mains wiring all around you as well.

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thgill
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Re: scart cable question - great picture but too much humm!

Postby thgill » Fri Apr 22, 2016 10:26 pm

I would also check your ground connections in the scart connector. Ideally all of them should be tied to ground including the outer shell and pin 4 (audio ground).
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