Re: Difference in luma-chroma delay of C64/C128 compared to standard S-video

Date: Mon, 4 Sep 2017 23:55:36 +0200
Message-Id: <>
> On 2017-09-04, at 18:49, smf <> wrote:
> On 04/09/2017 17:29, wrote:
>> I am not sure if we talk the same subject now. What I am trying to say is that there is no perceptible/measurable difference in Y/C timing between the separate and combined (composite) signals in a reference output. I can do the same with a 64, although - the same as Levente - I expect that whatever the modulator changes with its rather simplistic circuit is still negligible.
> Sure. Timing between composite, chrominance & luminance on an 8 pin would settle the debate.

This is on a 250466, don't know what exactly (what circuit) sits in the modulator there. While obviously the signal is far less clean from a 64 than from the generator, the results seem to be:

- C alone and C on the composite seem to be almost exactly the reversed phase.
- the "almost" is about plus 17ns for the composite C
- Y alone and Y on the composite seem to be about 23ns apart
- the "settling"[*] on composite is noticeably longer with some ringing

That makes it about 6ns difference in Y/C luma-chroma time relation between the separated and composite.

> My vague point was that if there is a difference and you're using a cable for a 5 pin c64 on an 8 pin c64 (so you're using composite video instead of chrominance) then try a different cable.

I see.

* - don't know the correct English term ATM.
SD! -

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Received on 2017-09-04 22:01:50

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