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  • Joined: 04 Nov 2020
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PAL SMSII in the US
Post Posted: Wed Nov 04, 2020 1:27 am
Hello all! Long time reader, first time poster here.

I am planning on bringing my PAL Master System II from Spain to the US but I have a few questions. At first I thought that all I needed to do was the 50/60hz mod in order to use it on a NTSC TV set but it seems there is more... I want to mod it to output s-video so I can use it on my crt KV-24FS100 but apparently the 50/60hz mod is not enough and the picture would be black and white.

I read that you need to add a new oscillator but I am kinda lost in here. Is there any schematics around that I can follow? Been looking for a while with no luck...

Thank you!
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Post Posted: Wed Nov 04, 2020 6:05 am
I don't have that TV model, but honestly I would be a little surprised if a Sony Wega TV that recent with a digital tuner couldn't decode PAL color too, at least at 50 Hz. Of course this applies to composite video input, an RF input could be more likely not to work given the different analogue TV RF tuning systems

Still, before you give up hope, try it :)

edit: ahhh, now I see - unmodded PAL Master System II is RF-only, so indeed it might be difficult. You could consider a mod perhaps? http://blog.tynemouthsoftware.co.uk/2018/12/sega-master-system-ii-composite-vide...

I forgot because my 50 Hz Master System II is the RGB version (from France)

Also separate analogue TV tuners with composite output do exist, it might be worth considering
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  • Joined: 05 Sep 2013
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Post Posted: Wed Nov 04, 2020 11:03 am
That TV has an analogue TV tuner (NTSC) so I would buy a NTSC Master System in the US instead of modding the PAL console and still not being sure about the TV capability of displaying PAL @ 60 Hz on composite.
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  • Joined: 04 Nov 2020
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Post Posted: Wed Nov 04, 2020 12:27 pm
Thank you all for replying.

I know the RGB mod would be ideal to not have to deal with that issue but I don’t have a PVM or a scart converter or the HDReteovision cables at this moment.

Buying an NTSC system is not an option so I’m all for modding the PAL one that I have.

I know PAL60 won’t work and that’s why I want to convert it to NTSC60. I guess my question is if it would be as simple as replacing the oscillator with a NTSC one (on top of the 60hz and composite/s-video mods).


Thanks!
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Post Posted: Wed Nov 04, 2020 2:47 pm
I think that TV might have S-Video input which would mean PAL. Vs. NTSC is irrelevant if you do an S-Video mod
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Post Posted: Wed Nov 04, 2020 2:55 pm
bsittler wrote
I think that TV might have S-Video input which would mean PAL. Vs. NTSC is irrelevant if you do an S-Video mod


TV set is NTSC and yes, it has s-video input (I use it for some other systems already).

Are you saying that the TV will take the s-video signal no matter if it’s color encoded PAL or NTSC?
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Post Posted: Wed Nov 04, 2020 3:01 pm
My apologies, you are right - the S-Video chrominance signal would be PAL encoded and it's possible the TV won't decode that correctly. In that case you would need either a new VDP or an RGB or component signal (and mod/cable) instead

Edit: actually new video encoder rather than new vdp

In any case PAL S-Video (or PAL composite) support seems more likely in a US TV of this vintage than support for tuning the PAL RF signal
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Post Posted: Wed Nov 04, 2020 4:25 pm
Forgot to mention: in at least some Wega models S-Video color encoding system can be changed in the service menu between PAL and NTSC. So be sure to check the service menu (which is typically hidden) before abandoning options
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PAL SMSII in the US
Post Posted: Thu Nov 05, 2020 2:03 am
The Black and White picture is due to the colour subcarrier frequency being different between NTSC and PAL as pointed out in the posts above. For NTSC the subcarrier frequency is 3.579MHz while for PAL it’s 4.43MHz. And the subcarrier has to be exact for colour to work.

As far as I know (I’m not a PAL/NTSC expert) Composite Video and S-Video do still use PAL/NTSC/SECAM video format. So modding the SMS2 to output Composite or S-Video would still result in a Black and White picture.

So, in theory, here’s what you would need to do to mod a PAL SMS2 for an NTSC TV:

1) Change out the 53.2034MHz Can to a 53.6931MHz Can (as used in the NTSC Sega Genesis).

2) Disconnect the 4.43MHz subcarrier between IC4 and the CXA1145 subcarrier input (pin 6).

3) Connect the CPU clock from either the Z80 or IC5 to the CXA1145 subcarrier input.

4) Put both the VDP and the CXA1145 from PAL mode to NTSC mode.

The subcarrier from IC4 goes through a 3.3K resistor and some capacitors before going on to the CXA1145. So this resistor may be a good point to change the subcarrier without cutting traces on the board etc, e.g. remove the 3.3K resistor and insert an inline 3.3K resistor on the pad connected to the CXA1145 only.

I’d be interested to know if this mod works if you end up trying it.
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Post Posted: Thu Nov 05, 2020 8:31 am
It seems like modding the TV for RGB may be simpler...
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Post Posted: Thu Nov 05, 2020 10:48 am
And here I was thinking that this wouldn’t be so hard lol

Thank you all for your help. I will update once I receive my system and I’m ready to destroy it.


Thanks!
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PAL SMSII in the US
Post Posted: Thu Nov 05, 2020 2:55 pm
Lol, well you asked :)

In simple terms, over the usual 50/60Hz mod, you would be doing the following:

1) Replacing the XTAL

2) Removing 1 resistor

3) Installing a wire.

I checked out a couple of videos on Youtube on modding TVs for RGB for gaming and I found them cringe-worthly @Maxim.

Firstly, I would seriously advise against anyone, without a good electronics knowledge, trying to modify a mains powered TV with CRT flyback voltage inside. Whereas the SMS2 is a low power, low voltage devices that's safe to open, a CRT TV can kill you. Having the videos suggest 'anyone can do this' was a bit reckless to me.

Secondly, the videos I watched were not simple mods. They involved reverse engineering schematics in service manuals, finding proprietary datasheets, and sniffing and parsing I2C communications which not everyone can do and vary from model to model for the hundreds of different TV's out there.

A hidden service menu where the encoding can be changed would be the best solution. Sounds like you need some luck on your side there.

Hopefully in the end, you will have a way to play games on your SMS2 in your new location.
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PAL SMSII in the US
Post Posted: Fri Nov 06, 2020 1:05 am
So some follow-up - I did see some CRT RGB mod videos that are not too difficult. But I would still caution anyone about diving into the guts of a CRT without electronics knowledge because it can definitely end very badly.
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Post Posted: Fri Nov 06, 2020 1:16 am
I have considered RGB modding my CRT but I’m not confident enough yet lol - I am very aware of how dangerous it can be if you happen to put your hand in the wrong place!

Besides my current setup is just for component and s-video systems so I don’t want to go down the SCART rabbit hole.

The Master System is on its way from Spain now so hopefully I can start testing soon.

PS: I checked my service menu and I did not see anything about being able to change the encoding. I read about some KV-FS100s that are in Argentina that accept all signals (lucky them!).
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Post Posted: Fri Nov 06, 2020 4:43 am
Another fairly affordable option, though not the best signal quality (composite - which already would require modding of the RF console - rather than RGB or S-Video) and might introduce slight lag (I have it but didn't try lag measurements) is a video system converter:

https://www.ebay.com/i/274182920860

Really I should hook it up and figure out whether it buffers frames or not/whether it does frame rate conversion. My vague recollection is it outputs NTSC-50 for PAL-50 input but it's been some time since I used it

edit: just tried this converter and was reminded of why it mostly doesn't get used here - it's very picky about signals and refuses to consider some devices’ outputs as "video" at all - PAL C64 included. I don't have a PAL SMS easily accessible to try with it, unfortunately, so I can't advise on whether that combination works. I have used it with PAL MSX computers successfully in the past, for whatever that's worth

edit 2: manual lag testing suggests this device introduces around three frames of lag. I don't currently have a lag sleuthing apparatus that can give an exact number. Games are noticeably unresponsive with this much lag, so I don't recommend it unless you're planning to play turn-based RPG's or something like that.
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Post Posted: Thu Nov 19, 2020 12:27 am
I also recently tried the Axun RGB-2YC which takes RGB in and puts S-Video and composite out with PAL or NTSC encoding. It is presumably lag-free. It is also rather pricey for this purpose. It generates usable NTSC, PAL, and PAL-60, but I was unable to get the PVM I was using to do color decoding for its NTSC-50 output. I'm not sure yet whether the incompatibility lies in the converter or in the PVM, though
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Post Posted: Tue Dec 01, 2020 12:51 am
Hi! My SMS2 is about to arrive so I am gathering the materials and preparing what I need to do.

These steps are clear:

1- Replace crystal oscillator with a 53.69 one.
2- Switch system to 60hz: Lift pin 57 in the VDP and tie it to ground.
3- Switch system to NTSC: Lift pin 7 in the encoder and tie it to pin 12 for +5v.


Now for the CLK frequency...

I found a video where the guy removes capacitor C26 and puts a 75ohm resistor in the positive hole, running a wire to pin 6 of the Z80 and that’s it...
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PAL SMSII in the US
Post Posted: Tue Dec 01, 2020 12:41 pm
Yeah that could work. C26 is between the resistor I was talking about and the subcarrier input on the CXA1145.
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Post Posted: Tue Dec 01, 2020 6:08 pm
Now I found someone claiming to not use C26 because it would be feeding the incorrect signal. Instead he recommends lifting resistor R10 and connecting it to the Z80. Is this the resistor you were talking about in your previous instructions?

Thanks!
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PAL SMSII in the US
Post Posted: Tue Dec 01, 2020 11:33 pm
Yep, R10 is the 3.3K resistor I was talking about.
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