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 Post subject: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 4:47 pm 


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I'm looking to put an Extron 201Rxi in the signal chain to my N64 for subtle sharpening and RGB control to the signal.

Can anyone tell me the best way to incorporate that? I have RGB scart from the console, and need RGB scart to the TV.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 4:51 pm 



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Does that add input lag or degrade the image? If not, I may look into this as well if needed.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 5:02 pm 


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It definitely doesn't introduce lag and shouldn't degrade the image - but you have to be subtle with the sharpening so as not to overdo it. I use it in my 480p CRT chain (VGA) and it works wonders with the Gamecube and Wii if you use it sparingly. The RGB control is nice as well as many of our CRTs over here ommited it for RGB signals. Plus the horizontal shift can be quite useful sometimes.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 5:28 pm 


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It's a full scaler, it's adding at least a frame of lag, possibly more. Fudoh may have a more precise idea about how much lag it adds.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 5:42 pm 


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The 201 rxi is an RGB interface


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 5:46 pm 


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Yes FinalBaton's right, it's just an RGB interface & I'm pretty sure there's no lag - you must be thinking of a different unit..


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 6:57 pm 


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I may have been thinking of the Emotia units, but I had thought the RGB interfaces took a 15 kHz signal in and output a 31 kHz signal. In any event, support for horizontal positioning must require a buffer of some kind...


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 7:00 pm 


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Guspaz wrote:
In any event, support for horizontal positioning must require a buffer of some kind...

No, just a PLL to generate a frequency-locked and slightly phase-shifted copy of the HSync signal


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 7:44 pm 


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Sorry, I meant vertical positioning, not horizontal. Although I suppose it could get around that without buffering by playing around with the vertical blanking interval...


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 7:56 pm 


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I just PM'd Fudoh who gave me some good info. I have a sync strike somewhere so I'll use that to input scart into the Extron. Then I can get scart out via BNC, although apparently it outputs TTL RGB sync (just trying to learn what that is) which might not be perfect for the consumer TV. We don't know exactly at what level the Extron outputs so I can put a resistor in the sync line (470 ohms to be safe).

Looking at a very old post (of mine!) I have to apply some voltage to pin 16 to avoid RGB blanking. I took 5v from the sync strike back then and it worked, although I was worried at the time that 5V might be too much - I really don't want to damage my TV!

Anyway I have 203Rxi coming soon so I'll dig out the sync strike and try it out. Apparently I should use DDSP if I get image distortion...


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 8:22 pm 


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Consumer TVs won't like TTL sync. It might appear to work, but it's like somebody standing next to you shouting into a megaphone: you're going to understand what they're saying, but you'll get permanent hearing damage.

Pin 16 should be 1-3 volts for RGB (1 volt nominal), so 5 volts is too high. This is why SCART cables for a console like the SNES, which outputs 5v, use resistors between the 5v and pin 16. I'm not sure if there is any standard for how much current a TV draws from this, though, so I don't know if it's even possible for there to be a correct resistor value... Tim's site suggests 180 ohm, though.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 8:50 pm 


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Thanks very much for that. I *really* don't want to damage this TV - I'll literally never find another like it.

So is TTL just the same as normal sync, just a higher voltage? Fudoh wasn't sure how much the Extron puts out so as I say suggested a 470 ohm in the sync line to be safe. Do you know how I can measure that after to be absolutely sure I'm not overdoing it?


As to pin 16, are you saying I could still take the 5V from the Sync strike and just put the 180 ohm resistor inline from that 5v to pin 16 and that would be 3V? I thought that would just limit the current? I'm not too hot on electronics..


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 9:35 pm 


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We're really getting outside of my knowledge here, I know enough to say "TTL voltage is too high" and I know enough to say "SCART says 1-3v so 5v is too high", but to go much beyond that...

Resistors can be used to drop voltage if you know the exact current that will be passing through... I'm not sure we can know exactly how much current a TV will draw from pin 16, but Tim Worthington's site seems to include a 180 ohm resistor on +v5 lines being fed into pin 16.

If I understand things correctly, a 180 ohm resistor with 5v inputs and a desired output range of 1 to 3 volts would mean the current must be somewhere between roughly 11 mA (would produce 3v) and 22 mA (would produce 1v).

For sync, you should really talk to somebody like Voultar.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 9:44 pm 


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Nice one. On the output I think I would need something like this:

https://www.retrogamingcables.co.uk/sony-pvm-scart-converter-bnc


Voultar would be a good guy to ask I think, I'll send him a PM.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 10:07 pm 


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I queried Voultar about the resistor on pin 16, he linked me to an article that indicates that the TV represents a 75 ohm load, with the article then suggesting that a 100 ohm resistor will get the voltage down to 2.1v, which is within spec.

Given that information, I think a 180 ohm resistor would still work, but would produce a 1.47v output in that scenario? Somebody should check my math.

So, I guess either one works, but Voultar's suggestion seems to be 100 ohm.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 10:10 pm 


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The problem in this particular case is though that the Extron doesn't provide a clean 5V source. And I don't think that splitting the sync line and using that as a switching voltage for the TV is a good idea.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Mon Jul 17, 2017 10:33 pm 


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Fudoh, I may have misunderstood you here, did you mean taking the 5v to correct the RGB blanking from the sync line? Sorry if I have this confused, but if you did mean that, then it's OK as the 5v is definitely coming from the sync strike.


Voultar replied that if the Extron outputs a 5V TTL sync signal, then I should do it this way:

EXTRON CSYNC OUT---------(470R)---------|+220uF|-----------TV

He says that should give about a volt with proper isolation and would be safe. Exactly the same resistance value as you gave as well which is reassuring.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Tue Jul 18, 2017 9:08 am 


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Apologies for the double post, I just worked out what I think is a good way of approaching it.


So I decided that I'l wait for the Extron to come and then when it does I'll connect my N64 to it via the sync strike. Then I'll measure the sync voltage coming off the Extron. Then, for the output, I'll contact Retrogamingcables.co.uk to make up a cable for me based on something like this:

https://www.retrogamingcables.co.uk/audio-video-accessories/scart-adapters/male-rgb-break-out-scart-to-4-x-bnc--2-x-rca-converter-cable


If the Extron's sync output level is at 5v, I'll ask them to to put in a 470ohm resistor and 220uF capacitor in the sync line as Fudoh and Voultar have suggested - then I can measure the new sync voltage which should hopefully be about a volt. And just to be extra safe, I'll just use an external power supply to supply 3v to pin 16.

As Fudoh pointed out in a PM, some people in the past (including me) had a problem with distortion at the top of the image using a sync strike with the Extron - but as he mentioned before, that can be sorted by using the Extron's DDSP setting. This disables the shift controls but that doesn't bother me as I don't need them.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Tue Jul 18, 2017 9:18 am 


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You don't want a cap on the sync line. That's a MD thing. Also - of course - order a cable with the right signal direction.


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 Post subject: Re: Exrton 201/3Rxi for sharpening & colour controls for N64
PostPosted: Tue Jul 18, 2017 9:26 am 


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Thanks Fudoh, just the resistor then. And will make sure to order the right direction as you say.


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