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In Reply to: RE: It's a matter of degree posted by Triode_Kingdom on July 21, 2016 at 08:10:42
Here's the thing..Back in the late 80s and early 90s,VCRs like TVS have been for years before,had gone to a switch mode power supply.The switching noise from the SMPS hasn't gotten into those circuits and with TVs and VCRs,we have RF,video,audio,and even an AGC delay line, all enclosed in a small area. This does show that a SMPS can be properly implemented to do its job but again,they were using shielding and small chokes on the main rail. This is why I think would be fine but I won't say for sure.
Notice on this VCR that the guy is working on,no longer has the switch mode supply separate with a shield.It actually part of the same board.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken
Edits: 07/21/16Follow Ups:
The video S/N of a VHS VCR is so bad, any SMPS noise is insignificant.Now in the mid 1980s I worked on a broadcast quality ANALOG color corrector which used an SMPS at first. We could not get rid of the noise until we put the supply in a separate box with ferrite cores on the cables.
Much better but still saw noise on a reference video monitor. Went to a large and hot linear power supply, that fixed it.
So yes, it is a matter of degree.
That said I have used small SMPS's on both analog video and audio gear since and have gotten away with it. But you need to be careful with layout.
Edits: 07/21/16 07/21/16
So the goal is VHS audio quality? You're right, that might be possible. :-)
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Edits: 07/21/16
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