Custom Scart to S-Video cable has no colour

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gyrogearloose

22 posts

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#36119 19-Jun-2009 13:27

I thought I'd ask this question before I disassemble the cable to try swapping the chroma & luminance.

I've made a custom scart to S-Video & 3.5mm stereo jack to connect the Sky VCR output into my Hauppauge HVR2200 tuner card. I used the pinouts suggested by Cyril as well as the S-Video page from Wiki, but it's possible I've confused the diagram showing the S-Video plug and reversed the chroma & luminance signals.

I'm getting a clear picture, but no colour - is this the symptom of reversed chroma & luminance?

I've been into the Sky setup and selected S-Video on the VCR output. I've checked the cable using a multimeter looking for continuity and shorts. The pins on the S-Video plug are not bent. I've plugged the S-Video directly into the TV, where a known good S-Video signal was working, and again no colour.

So, opinions, is this the symptom of reversed chroma & luminance? Is this a sing that the Sky decoder is still outputting Composite, rather than S-Video? Have I made a mistake with wiring the scart plug, here follows the pins used:

Audio:
1 Right Audio
3 Left Audio
4 Audio Gnd

S-Video:
19 Luma
17 Luma Gnd

15 Chroma
13 Chroma Gnd

cyril7

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#226744 19-Jun-2009 16:14

Hi, if you have reversed Chroma and composite then you get no Luma channel, so not even a black and white pic. I suggest the other problem other than bad connection is you may need to terminate the chroma channel with a 470ohm resistor, this is a common problem with many DVB boxs and the way they interact with many TVs.

Cyril

gyrogearloose

22 posts

Geek

#226977 20-Jun-2009 11:45

Thank you - I did some more experimentation and while I appear to have resolved this problem it leaves me horribly confused about the capabilities of my Sky decoder.

My Sky decoder is a Zenith DTH310-4, and as well as making this Scart to S-Video and 3.5mm jack from the VCR port to my HTPC card (replacing a UHF connection), I intended to make up a Scart to Component cable to replace an existing Scart to Composite. My TV has inputs labelled Y Pb Pr, which I expected to be able to use with the Sky Scart option for RGB output (I'm thinking this is a nomenclature discrepancy, rather than a format difference - give an opinion if you want, but this is actually unrelated to my problem).

Anyway, my experimentation: I plugged the custom Scart to S-Video connection from the VCR port on the Sky decoder to a known good S-Video port on the TV, and it was Black & White. I went back into the Sky Scart setup and changed the VCR port back to Composite - the TV lit up in colour, but I could tell it was composite because it had dot crawl on graphics, and I had no other signal plugged in anywhere else.

So I was getting a composite signal over an S-Video cable - ok, I accept that is possible.

Then, I tried changing the Sky Scart setup for the TV port - as I said above, I intended to make a Scart to Component lead. So I changed the Sky Scart setup for the TV port to RBG - what I now discovered was that the Sky Scart setup for the VCR port ONLY ALLOWED COMPOSITE. S-Video was no longer a valid option.

So I thought, 'OK, I really want to use the S-Video connection to my HTPC, more than I want to use Component to my TV'. SO I SWAPPED THE SCART PLUGS BETWEEN THE TV AND VCR PORT, and set the TV port to S-Video (this is attached to my custom Scart to S-Video cable) and set the VCR port to Composite (this is attached to a composite port on the TV)

And now the S-Video output is perfect, definitely S-Video with no dot crawl.

And the Composite output is, well, composite, but my objective is to use the HTPC as the primary device and make the recordings through the S-Video connection as good as possible.

So, and I realise I've probably confused everyone, to summarise my observations: The S-Video coming out of the VCR port on this decoder was black and white, but, the S-Video coming out of the TV port is perfect.

So, my question is, has anyone else had this problem on a Zenith DTH310-4, and, is there a better decoder available from Sky, where I could ring and say "I want xxx Model because I've changed my equipment and want to get an S-Video and Component output". Thanks for listening.....

gyrogearloose

22 posts

Geek

#226980 20-Jun-2009 11:55

A clarification: I didn't bother testing whether I could get good S-Video from both ports at the same time, since the only S-Video input on the TV is already connected to the HTPC (which has no other connection option until I upgrade to an LCD with HDMI).

cyril7

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#226982 20-Jun-2009 12:11

Hi, if you select RGB or Component on the Video SCART then you can only get composite on the VCR port, this is not only unique to Sky boxs but to most DVB SCART devices, they simply dont have enough video drivers to do all combinations and purmutations.

I think you will find that you will get S-Video from both TV and VCR SCART at the same time if selected but I cannot confirm as I dont have that exact box to hand. Dont expect too much support from Sky on these matters.

Cheers
Cyril