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S-Video
Post Posted: Sun Aug 01, 2010 12:03 am
Not sure if this is the proper place... but I purchased this old Panasonic 1331Y monitor that appears to be meant for studio monitors and the like. It has great clarity even on composite (had to splice my own wires since it uses BNC connectors) but it also has an S-Video input on it as well. It has a switch for a 75ohm mode and something called "HI-Z."

Basically, my question here is, what do I need to do to get the SMS to output S-Video? It's a US Model 1 with Hang-On/Safari Hunt/Snail Maze BIOS.

Also, I believe this monitor may have RGB, but I'm unsure. It has a VTR connector on the back with 8 pins. It could control something for a video camera though. If anyone wants to help me figure out what it's purpose is I'll appreciate it. (And yes, I tried googlin'.)
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Post Posted: Sun Aug 01, 2010 12:27 am
Upon closer research (finally found a proper pinout) the 8-pin VTR seems to be useless to me.

http://freespace.virgin.net/matt.waite/resource/av/8pinvtr.htm

I just ran a wire from the composite on the SMS to the video in and ground to vid in ground and it shows a scrambled picture, similiar to the old days of premium cable. I wonder if it's worth trying to get it to work and if so if there's some sort of circuit that needs to be built in order for it to work.
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Post Posted: Sun Aug 01, 2010 9:45 am
Here is your S-Video (and RGB) mod:
http://www.smspower.org/Development/VideoOutput
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Post Posted: Sun Aug 01, 2010 10:12 am
Note on s-video: the circuit given in that diagram will cause the image to slightly loose sync when a certain off-white colour is used. Instead of the resistor and capacitor for the Luma and Chroma signals, you'll need an NPN transistor and a 33 ohm resistor. Connect the CXA1145P output into the transistor's base, connect +5v to the collector, and connect the transistor's emitter to the resistor. The other end of the resistor goes to your monitor.
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Post Posted: Sun Aug 01, 2010 2:28 pm
albino_vulpix wrote
Note on s-video: the circuit given in that diagram will cause the image to slightly loose sync when a certain off-white colour is used. Instead of the resistor and capacitor for the Luma and Chroma signals, you'll need an NPN transistor and a 33 ohm resistor. Connect the CXA1145P output into the transistor's base, connect +5v to the collector, and connect the transistor's emitter to the resistor. The other end of the resistor goes to your monitor.



Any particular NPN you recommend? I remember seeing a thread somewhere on here with someone claiming a specific one worked out better for them.
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Post Posted: Sun Aug 01, 2010 10:35 pm
I don't think it's particularly important. The 2N3904s I used work great.
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Post Posted: Mon Aug 02, 2010 12:07 am
albino_vulpix wrote
I don't think it's particularly important. The 2N3904s I used work great.


Looks like I can grab them at Radio Shack. I'll give it a go sometime this week. Seems pretty basic.
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Post Posted: Mon Aug 02, 2010 3:01 am
Australia, like the United States, suffers from having no SCART =(.

We do have Component video though, is it possible to get component video out of this chip? Maybe that'll be a better option with slightly better picture even than s-video.

If it is not possible could someone please draw a schematic of how this s-video thing with the transistor is done? I purchased a modified mega drive with s-video and it does have that flashing graphics problem on certain bright colours, I'd rather do it properly myself on a Master System.
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Post Posted: Mon Aug 02, 2010 3:04 am
Alternatively, is it possible to get component video from the 8-pin DIN? I could make my own cable if I knew how!
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Post Posted: Mon Aug 02, 2010 8:37 am
albino_vulpix is perfectly right, the circuit with the transistors works much better. Hardware mods page should be updated too...

More details on mods can be found in the forum:
http://www.smspower.org/forums/viewtopic.php?t=10756&postdays=0&postorder=asc&highlight=rgb+mod&start=0
http://www.smspower.org/forums/viewtopic.php?t=11586&highlight=svideo

Video chip can't output component video. You can use a RGB to component video circuit like this:
http://www.jrok.com/hardware/RGB.html
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Post Posted: Mon Aug 02, 2010 1:01 pm
Who wants to update that page then?
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Post Posted: Tue Aug 03, 2010 1:05 am
Maxim wrote
Who wants to update that page then?


I can make an attempt to do it, but where do I draw +5 from, would it just be easiest to attach to the +5VDC from pin 5 of the AV or is there a better place? I don't have access to a multimeter at present, and my SMS is the typical American SMS.

And I'll update the schematic for it to include RGB as well. Does that stay the same with cap and resistor or do those use NPN also?
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Post Posted: Tue Aug 03, 2010 1:52 am
karagh wrote
albino_vulpix is perfectly right, the circuit with the transistors works much better. Hardware mods page should be updated too...

More details on mods can be found in the forum:
http://www.smspower.org/forums/viewtopic.php?t=10756&postdays=0&postorder=asc&highlight=rgb+mod&start=0
http://www.smspower.org/forums/viewtopic.php?t=11586&highlight=svideo

Video chip can't output component video. You can use a RGB to component video circuit like this:
http://www.jrok.com/hardware/RGB.html


I don't plan to use component, but out of curiosity... will using the RGB to component degrade the signal quality or is it so minute that it's not worth complaining about?
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Post Posted: Tue Aug 03, 2010 8:00 am
Maraakate wrote
Maxim wrote
Who wants to update that page then?


I can make an attempt to do it, but where do I draw +5 from,

The page says that there's +5V on pin 12 of the video chip.
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Post Posted: Tue Aug 03, 2010 8:46 am
RGB is what the electronics produces first. Any signal derived from it (be it component YPbPr, s-video, composite, or HDMI) will be degraded.
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Post Posted: Tue Aug 03, 2010 10:19 pm
Had a chance to sit down and do the S-Video mod today. It works good, except I used a 100ohm by accident, radio shack threw the 100ohms in the 33 ohm bin and I didn't bother to check until after I assembled the SMS, which may explain why the colors were rather dark. I had to set the switch to "HI-Z" to get it bright. (I'm not quite sure what the HI-Z is on the monitor, and I can't find literature on it, but I think it has something to do with some sort of amplifier for brightness, pushing the switch the other way is 75ohm, so *shrugs*).
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Post Posted: Tue Aug 03, 2010 10:20 pm
Also, Pin 24 is a ground and I believe I was reading in a post or on the wiki (can't remember which) that it was a +5 point. Ran the +5V to pin 12 and ground to Pin 24.
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Post Posted: Wed Aug 04, 2010 12:04 am
Generally, "Hi-Z" means high impedance. So as opposed to 75ohm input, it's like an infinate ohm input.
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Post Posted: Wed Aug 04, 2010 12:26 am
albino_vulpix wrote
Generally, "Hi-Z" means high impedance. So as opposed to 75ohm input, it's like an infinate ohm input.


So, what does this mean for me exactly?
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Post Posted: Wed Aug 04, 2010 3:32 am
The inside of your monitor has resistance between the video input and ground. It's almost always 75 ohms. With this s-video amp, this resistance is the equivalent of another resistor after the 33 ohm. Without going in too much depth, the current must drop some of its voltage to flow through the resistor; and how much depends on the resistance. Because the resistor value you used is too high, the current drops too much voltage, leaving a weak signal for the monitor. The image is bright in hi-z mode because the monitor's resistance is now much greater than than the resistor on your circuit, meaning almost all the voltage is being fed to the monitor.
.
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Post Posted: Wed Aug 04, 2010 7:04 pm
albino_vulpix wrote
The inside of your monitor has resistance between the video input and ground. It's almost always 75 ohms. With this s-video amp, this resistance is the equivalent of another resistor after the 33 ohm. Without going in too much depth, the current must drop some of its voltage to flow through the resistor; and how much depends on the resistance. Because the resistor value you used is too high, the current drops too much voltage, leaving a weak signal for the monitor. The image is bright in hi-z mode because the monitor's resistance is now much greater than than the resistor on your circuit, meaning almost all the voltage is being fed to the monitor.
.


So is HI-Z meant to fix cables with a higher resistance?

Also, finally replaced them with 33 ohm resistors, looks great! Thanks to everyone who helped out. Now I just gotta get on that schematic for the wiki.
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Post Posted: Thu Aug 05, 2010 2:58 am
To be perfectly honest, I have no idea what it's for.
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Post Posted: Thu Aug 05, 2010 6:38 am
Maraakate wrote
albino_vulpix wrote
The inside of your monitor has resistance between the video input and ground. It's almost always 75 ohms. With this s-video amp, this resistance is the equivalent of another resistor after the 33 ohm. Without going in too much depth, the current must drop some of its voltage to flow through the resistor; and how much depends on the resistance. Because the resistor value you used is too high, the current drops too much voltage, leaving a weak signal for the monitor. The image is bright in hi-z mode because the monitor's resistance is now much greater than than the resistor on your circuit, meaning almost all the voltage is being fed to the monitor.
.


So is HI-Z meant to fix cables with a higher resistance?


If you connect more than one monitor to a single video source you set one monitor to 75 ohms and the others to HI-Z.
 
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Post Posted: Thu Aug 05, 2010 8:00 pm
viletim! wrote
Maraakate wrote
albino_vulpix wrote
The inside of your monitor has resistance between the video input and ground. It's almost always 75 ohms. With this s-video amp, this resistance is the equivalent of another resistor after the 33 ohm. Without going in too much depth, the current must drop some of its voltage to flow through the resistor; and how much depends on the resistance. Because the resistor value you used is too high, the current drops too much voltage, leaving a weak signal for the monitor. The image is bright in hi-z mode because the monitor's resistance is now much greater than than the resistor on your circuit, meaning almost all the voltage is being fed to the monitor.
.


So is HI-Z meant to fix cables with a higher resistance?


If you connect more than one monitor to a single video source you set one monitor to 75 ohms and the others to HI-Z.


Thanks for the clarification!
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Post Posted: Mon Aug 23, 2010 11:02 pm
A little off-topic, but could I apply this same exact circuit to a model 1 genesis or do I have to build this slightly more complicated one detailed http://www-unix.ecs.umass.edu/~dhowland/mod/ ?
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Post Posted: Tue Aug 24, 2010 1:37 am
I'm going to assume as much considering they're the same exact chipsets.
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Post Posted: Tue Aug 24, 2010 10:09 am
The simpler circuit you already made should work.
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Post Posted: Tue Aug 24, 2010 9:20 pm
Tycho wrote
Australia, like the United States, suffers from having no SCART =(. We do have Component video though, is it possible to get component video out of this chip?


I'm also interested in this. Is there a way to get a top-quality image on my SCART-free TV without buying an expensive converter?

Quote
Alternatively, is it possible to get component video from the [AV port]?


Is it even possible to get S-Video from the AV port?
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Post Posted: Tue Aug 24, 2010 9:24 pm
Actually SCART RGB was available in Australia. It was really only made available on really high end CRT sets but if you have a look around on eBay Tycho you should be able to find a good cheap RGB CRT TV.

Then you can play all those older consoles in glorious RGB
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Post Posted: Tue Aug 24, 2010 9:25 pm
Paul Baker wrote
Tycho wrote
Australia, like the United States, suffers from having no SCART =(. We do have Component video though, is it possible to get component video out of this chip?


I'm also interested in this. Is there a way to get a top-quality image on my SCART-free TV without buying an expensive converter?

Quote
Alternatively, is it possible to get component video from the [AV port]?


Is it even possible to get S-Video from the AV port?


According to this, http://www.smspower.org/Development/AVPort , all you would be able to get is RGB and Composite (Yellow RCA) from the AV Port. And I'm not sure if the traces that lead to the RGB pins to the CXA chip have caps, etc, running to it or if it's a single trace, if it's a single trace you could build the circuit inside the actual wire itself.

Here, http://www.guildserver.co.uk/data_images/CXA1145/CXA1145.PNG , is a pinout of the CXA1145 chip itself. And I'm not sure how component works exactly and if it's possible to build something feeding from those pins.
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Post Posted: Tue Aug 24, 2010 9:34 pm
Emuaust wrote
Actually SCART RGB was available in Australia. It was really only made available on really high end CRT sets but if you have a look around on eBay Tycho you should be able to find a good cheap RGB CRT TV.


Good point - it'll probably be cheaper to buy an older TV than to buy a SCART->component converter.
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Post Posted: Tue Aug 24, 2010 10:24 pm
Paul Baker wrote
Emuaust wrote
Actually SCART RGB was available in Australia. It was really only made available on really high end CRT sets but if you have a look around on eBay Tycho you should be able to find a good cheap RGB CRT TV.


Good point - it'll probably be cheaper to buy an older TV than to buy a SCART->component converter.


Not to mention there's something oddly satisfying about playing old school systems on old school televisions and monitors :D
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Post Posted: Tue Aug 24, 2010 10:28 pm
You can get S-video and AV from the CXA-1145 using these instructions: http://www.smspower.org/Development/VideoOutput
Not sure how much more work needs to be done to get component though.
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Post Posted: Tue Aug 24, 2010 10:54 pm
paul_ wrote
You can get S-video and AV from the CXA-1145 using these instructions: http://www.smspower.org/Development/VideoOutput
Not sure how much more work needs to be done to get component though.


I believe he was asking if you could physically just make some sort of cable that plugs into the A/V port for S-Video, like you could with Composite. That mod shown in the wiki is outdated. I still haven't found time to update it.
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Post Posted: Tue Aug 24, 2010 11:00 pm
Oh whoops :-)

Did some googling around RGB to component. Found this: http://www.sega-16.com/forum/showthread.php?t=6514

Schematics for an RGB to component box, but looks like it takes sync-on-green RGB input. Since the sega AV plug has a separate sync output (pin 1) it is probably not sync-on-green so the sync will need to be added to the circuit somehow.

Might be helpful for anyone looking to do this in the future
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Post Posted: Wed Aug 25, 2010 1:00 am
paul_ wrote
Schematics for an RGB to component box, but looks like it takes sync-on-green RGB input. Since the sega AV plug has a separate sync output (pin 1) it is probably not sync-on-green so the sync will need to be added to the circuit somehow.


I don't know how one would go about converting the AV port's RGBS to RGsB as apparently needed by that box.

However, I have found this, which takes a SCART input so should have no trouble converting an RGBS signal to component (with sync-on-Y).

My only concern is that an SMS SCART cable may (and indeed does in this mod) carry not just composite sync on pin 20, but a full composite video signal. That is: pin 20 of the SCART may be connected to AV port pin 2 (equivalent to CXA1145 pin 20, C VIDEO OUT), rather than AV port pin 1 (equivalent to CXA1145 pin 11, CSYNC OUT).

Does anyone know if this is likely to cause a problem with the RGBS -> component converter?
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Post Posted: Thu Aug 26, 2010 4:14 pm
is this correct? http://cgi.ebay.com.au/SCART-COMPONENT-YUV-Video-Audio-5m-FOXTEL-NEW-/370421166965?pt=AU_Electronics_Accessories_Wires_Cables
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Post Posted: Fri Aug 27, 2010 2:31 am
That is simply an adaptor; it does not convert the signals.
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Post Posted: Fri Aug 27, 2010 3:08 am
Tycho wrote
is this correct?

albino_vulpix is right - if you connect that cable to the end of an RGB SCART cable, two of the RCAs will carry audio and the other three will carry R, G and B.

The reason it is advertised as a "component YUV" cable is that some devices can output component over SCART, using the pins designed for RGB. The SMS cannot do this.
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Post Posted: Sun Aug 29, 2010 3:07 pm
So I guess getting Component out of a Master System would be expensive. Pity :(
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Post Posted: Sun Aug 29, 2010 3:31 pm
They do make converters that can turn SCART/RGB into VGA. The boxes are quite pricey (about $350 USD last time I checked) but I do have some nice big monitors that have great colour and picture quality I'd love to see it on.

I'm not a big fan of LCD, CRTs appear to have brighter colour IMO. Older games seem to look better on CRTs anyways (probably because they were designed for them!). I've been thinking about buying one of these converters but I'd rather focus on building up my collection atm.

If anyone is interested going this route, here's one I see advertised quite frequently:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280538916048&rvr_id=1...

I'm sure most of you have seen this article before, but here's some tips on picking a suitable monitor to get RGB out of:

http://nfggames.com/atarilabs/meat/2000/1201_rgbprimer.shtml
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