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Author Topic: Vga to Scart cable all colors correct except white which is grey  (Read 1582 times)

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telonio

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I have made a vga to scart cable and using Groovy mame I can see picture in the crt tv (pal).

All colors are good except white which is grey for some reason.

If you notice in the pic below you will see the high score that it is grey and it should be white. Also the eyes of the green dinosaur are grey and they also should be white.

I have checked multiple times the cable from both ends and can I verify that all connections are  good.

Anynone has an idea what could possible be this issue?

Thanks


Zebidee

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #1 on: April 13, 2022, 08:18:48 am »
White is just a mix of all three colours together, so the issue could be in your RGB lines. The colours look a little weak to me. It could also be the TV is a bit tired or needs some tweaking, so worth checking it with another input if available.

Not all VGA cables are the same, especially if you have recycled a VGA cable from an old monitor. Worth checking before you start, caused me to have to scrap VGA-SCART cables I've made before.

You can check resistance on your cable with a multimeter in ohms mode. You shouldn't get more than a few ohms resistance from end to end.

Make sure all your video grounds are connected.
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telonio

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #2 on: April 14, 2022, 03:06:55 pm »
It's a brand new cable with a new vga and a new scart. Is there a ground cable in the sliver metal cover of the scart or am I wrong?

Zebidee

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #3 on: April 14, 2022, 05:34:12 pm »
It's a brand new cable with a new vga and a new scart.

Just test the RGB and sync lines with a multimeter, like I suggested before. Also, go find an alternative input for the TV, like a DVD player or something, so you can see if the TV colours are just dull anyway. Maybe it is getting a bit tired.

Quote
Is there a ground cable in the sliver metal cover of the scart or am I wrong?

I'd leave it alone completely. Usually metal covers are connected to shield ground, if anything. Not the same as video ground.
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telonio

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #4 on: April 17, 2022, 03:14:00 pm »
I have checked with the multimeter the RGB and groud lines and they are all ok. I even make another vga to scart cable and I still got the same issue with white.

With two cables and the issue persits, I am thinking if this may be an issue of the graphica card (I use HD5450 1GB) or it may be something wrong on the crt emu driver.
I want to setup the crt emu driver again in a different hard drive, but I am not sure that this will fix the issue.

Zebidee

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #5 on: April 17, 2022, 10:41:03 pm »
Make sure you have no connectivity between RGB lines and ground as well, except when the cable is connected to the TV (then you can expect ~75ohms to ground).

You can use the ATI Catalyst Control Center (or whatever they call it) utilities to adjust your colour temperature/intensity. Some cards will have different default colour output levels to other cards, however it can be adjusted to your eye. In particular with a 5XXX card of mine, I found the colours needed the "warmth" setting adjusted from around 6500k to about 7000k.

It may also be that your TV tube is old and tired. The RGB guns wear out over time. On the other hand, if you can access the TV service menu, you may be able to adjust colours there. Some TVs will have pots, probably on the neckboard, for colour gain and cutoff. Mostly you can leave the pots alone, but if all else fails.

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telonio

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #6 on: April 18, 2022, 11:01:09 am »
I tried in 2 different pal crt tv's and I got the same issue. I have a second sata hard drive, I will setup windows and crt emu driver and see if there's any improvement.

Zebidee

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #7 on: April 18, 2022, 03:43:49 pm »
If it isn't the cable and it isn't the TV, then I guess the issue must lie with the video card.
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buttersoft

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #8 on: April 18, 2022, 06:08:18 pm »
In particular with a 5XXX card of mine, I found the colours needed the "warmth" setting adjusted from around 6500k to about 7000k.

I had one for a while that was just... bad. Colours were a bit grey and washed out. Not the same as the OP, but i guess it might be that.

telonio

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Re: Vga to Scart cable all colors correct except white which is grey
« Reply #9 on: April 19, 2022, 12:44:47 pm »
I am looking to find a different ati graphics card locally.