[SOLVED] Scart output color issue on my Sony Trinitron TV

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Tibob
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[SOLVED] Scart output color issue on my Sony Trinitron TV

Post by Tibob »

Hi,

First of all sorry for my poor english :oops:

I've just assembled my IO board v5.5. The VGA to scart cable is provided by Lotharek.

First of all, I've tested the VGA output on a Thomson TV via scart plug. Everything works like a charm, great picture and vibrante colors.

Secondly, I've tested on a sony trinitron and the result is really disapointed... The colors are fadded, especialy the red one.

Someone have some advices about this issue? Thanks in advance.
Last edited by Tibob on Thu Feb 21, 2019 11:31 am, edited 1 time in total.

zomgugoff
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Re: Scart output color issue on my Sony Trinitron TV

Post by zomgugoff »

The cable my have in-line capacitors and/or resistors that SCART TVs usually need, but the output from the VGA port may not be hot enough to need them.

Tibob
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Re: Scart output color issue on my Sony Trinitron TV

Post by Tibob »

Yes, I thought about that too. I m going to make my own cable with 75ohm resistors and 220uf capacitors.

Thanks for your help

Tibob
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Re: Scart output color issue on my Sony Trinitron TV

Post by Tibob »

I made my own cable with capacitors and résistors and no change... :(

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Re: Scart output color issue on my Sony Trinitron TV

Post by Sorgelig »

If colors are faded then it's not enough voltage on RGB. So instead to add 75 Ohm resistors it's better to check what resistors are used in TV and may be increase them a bit to let the higher voltage to go.
But you need to understand what are you doing, so you won't damage anything.

optiroc
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Re: Scart output color issue on my Sony Trinitron TV

Post by optiroc »

Some Sony TVs are peculiar about the level on the sync signal, and wrong levels can yield the funky side effects you describe.

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Re: Scart output color issue on my Sony Trinitron TV

Post by JamesF »

1k resistor on the sync line fixed the faded color issue on my 2002 Trinitron.
Some newer consumer sony trinitron tv's don't like anything above 300mV of sync level, else the colors are affected.

Tibob
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Re: Scart output color issue on my Sony Trinitron TV

Post by Tibob »

First of all, thanks Sorgelig for yours precious advices, moreover, thanks for all the work you've done! Mister is a great project, i'm very excited about it!

About my issue, thanks optiroc and in particular JamesF. The 1K resistor on sync line works great! Great picture on My sony CRT :) SUCCESS!!


I've already done the SDram add-on, SNES core works very well, can't wait to try the others cores (my 128 go card is waiting for that :) )

Optiuk
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Re: [SOLVED] Scart output color issue on my Sony Trinitron TV

Post by Optiuk »

Hello,

Just came across this thread whilst troubleshooting Mister colour issues using a uk consumer RGB scart enabled Sony crt post year 2000 model
(Similar issue discussed here: https://shmups.system11.org/viewtopic.php?f=6&t=58861).
Excuse my ignorance but is it preferable to solder the 1k resistor via the scart connector or VGA connector end of the cable? Thanks in advance!

(Would be interesting to see if there are any prebuilt scart breakout boxes with potentiometer adjustment for sync line, or possible to add this to an existing box which I own, which I'm planning to do if I can't find one. This would be a easier option an allow adjustment from other sources such as PC 15khz signals as well as Mister. I suspect there are quite a few people with this issue that are not aware of cause, favouring later year Trinitrons due to usage time).

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DrOG
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Re: [SOLVED] Scart output color issue on my Sony Trinitron TV

Post by DrOG »

Optiuk wrote: Excuse my ignorance but is it preferable to solder the 1k resistor via the scart connector or VGA connector end of the cable? Thanks in advance!
(Would be interesting to see if there are any prebuilt scart breakout boxes with potentiometer adjustment for sync line...).
The localisation of the resistor doesn't matter, as the cable you use has very low (near zero) impedance.
Feel free to use a 2k potentiometer instead of the 1k fix resistor, so you will able to adjust/fine tune it's value is necessary.

Optiuk
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Re: [SOLVED] Scart output color issue on my Sony Trinitron TV

Post by Optiuk »

DrOG wrote:
Optiuk wrote: Excuse my ignorance but is it preferable to solder the 1k resistor via the scart connector or VGA connector end of the cable? Thanks in advance!
(Would be interesting to see if there are any prebuilt scart breakout boxes with potentiometer adjustment for sync line...).
The localisation of the resistor doesn't matter, as the cable you use has very low (near zero) impedance.
Feel free to use a 2k potentiometer instead of the 1k fix resistor, so you will able to adjust/fine tune it's value is necessary.
thanks will give a 2k potentiometer a go. No change after fitting a 1k resistor so looks like fine tuning according to tv is the way to go.
One way to view the red/brown colour difference is switching off RGBs via a breakout box and switching to composite signal.

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Re: [SOLVED] Scart output color issue on my Sony Trinitron TV

Post by Optiuk »

2k potentiometer solved the issue, picture now looks superb, thanks again!

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Re: [SOLVED] Scart output color issue on my Sony Trinitron TV

Post by Edhel »

Just wanted to say thanks to the input from others given on this thread. I was starting to think there was an issue with a vga to scart cable I'd ordered from amigakit.

Colours were all washed out on my sony trinitron crt tv. Though when I tried it on a cheap portable crt tv, it worked fine. After reading this thread, I soldered a resistor to the csync part of my scart cable and all is well. Only had a 1.2k resistor at hand instead of the mentioned 1k, but worked perfectly.

Cheers. :D

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