Master System - some modding/cabling advice needed

[ASDR]

Hi all,

I picked up a Model 1 PAL SMS. I don't really need one since I already own a perfectly fine & backwards compatible MD1, but hey, this thing looks cool and it was real cheap. Some questions:


- I forgot how much PAL consoles sucked. The borders are gigantic, image squished and the Out Run music sounds like a lullaby. The PAL-suck is strong with this one. Is there a reasonable way to mod these units to NTSC?

- My system came with a home-made looking SCART RGB cable, but it's not shielded, wired for sync-on-composite, and missing the AC decoupling caps. There's some audio buzz and jailbars. Normally I'd just buy a quality cable from RGC, but that costs more than the console + controllers + games, so I'd like to maybe reuse / repurpose something I already own. The SMS1 is fully compatible with both csync and sync-on-composite MD1 cables, correct? I think I still have a MD2 cable from thefoo.83, maybe I could just get a MD2->MD1 adapter?

- This console has industrial strength jailbars. I've seen some jailbars on Famicom, PCE, MD etc., but this one got them all beat. Any remedy for this? I've read about doing a full RGB bypass, but again, something like that triple bypass board costs more than I paid for this whole thing. Is there anything small-scale, i.e. replace / add a few caps, cut some traces, etc. that I could do to improve the picture?


Thanks!

[VajSkids Consoles]

Apparently on the model one the only issue that it is wired for sync over composite, and this causes the jailbars.
You just rewire it with Pin 11 as sync (CXA1145p) this is C sync.. run it through a cap just to be sure. I've never had any issues with any of master systems, megadrive or SNES with sync straight off the IC pins and the SNES and MD are TTL 5v, from what I've read even though it works its best to run them through a 470ohm resistor with a cap, 220/470uf

I'm not an expert on the topic but I've certainly modded a few systems. i just run pin 23/22/21 (RGB) through a 75ohm resistor (or its too bright) on the model 2's to your output.
As for the black borders and your 17~% speed increase so the games run at their intended speed, this is the 4th LONG leg in from the R/H side and bottom of the sega IC which you can just lift and run to 5v for permanent 60hz, or a switch to have it between GND/5v... I have these pinouts printed out but I can't see the writing on the IC sorry. Just do some research.

and yeah a MD1 SCART cable will work, but you still need to switch pin20 across to C sync (as in Pin20 on the SCART head, maybe add a switch so you can retain composite output). I had no issues with picture quality using composite on the model 2's but I did have certain games completely losing picture in certain parts until I used C sync.

[ASDR]

So you're saying on the SMS1 pin 7 here on the AV out does not carry csync? I have to modify the console and tap it from the CXA before I could use the SMS1 with my csync-MD1 cable?



Good to hear you can relatively easily do a PAL->NTSC modification. Do PAL games still work and just run at the intended 240p/60Hz when plugged into an NTSC console? What about the BIOS, do I need to burn and install an NTSC/NTSC-J BIOS as well? Do I also need to swap out an oscillator to get the on-spec 59.94Hz refresh?

Thanks!

[VajSkids Consoles]

So you're saying on the SMS1 pin 7 here on the AV out does not carry csync? I have to modify the console and tap it from the CXA before I could use the SMS1 with my csync-MD1 cable?



Good to hear you can relatively easily do a PAL->NTSC modification. Do PAL games still work and just run at the intended 240p/60Hz when plugged into an NTSC console? What about the BIOS, do I need to burn and install an NTSC/NTSC-J BIOS as well? Do I also need to swap out an oscillator to get the on-spec 59.94Hz refresh?

Thanks!

For RGB it doesn’t matter about the crystal, on composite yeah, you’ll get black and white.

Games all run fine at 60hz. Haven’t encountered any issues.

You’ll find a mixture of information on the internet. Some even saying use C sync In. I’ve seen other posts showing that the C sync out doesn’t go anywhere so yes, you have to manually wire it. Should just need a 75 ohm resistor.. I haven’t needed caps for my SMS RGB PAL mods ...they haven’t made a difference.

It’s probably best Just to have a look and check with a multimeter and your eyes. I haven’t played with model ones as much. I did put Tims FM board in one of mine and used the switchless reset mod for 50/60hz but this resets the game each time and its pretty pointless when you can do a simple switch or wire it for permanent 60hz.

https://m.youtube.com/watch?v=jR7jAQ2e9TQ

Here this guy has you covered.

[VajSkids Consoles]

And his part 2

https://youtu.be/_mk-vZXF2wo

Haven’t watched these through, they’re quite long. Plus using pinouts and a multimeter is quicker than his video, plus the model 2’s modded don’t suffer from crazy jail bars.

This is 75ohm resistor on RGB out lines, and just a 220uf cap on C sync out on a model 2, and shows the 50/60hz switch on a home made break out cable with 8 pin DIN from Jaycar.


https://i.imgur.com/ILQcmg8.mp4

[ASDR]

Ok, thanks a lot.

I'll start by installing a 50/60Hz mod with the switch in the FM expansion compartment. I doubt I'll ever install an FM module in this unit, if I really want that I can use my MD1+Everdrive X7 combo.

I did some reading and it seems that you need to swap the oscillator/crystal if you want a perfect on-spec refresh rate. There's also a european modshop that offers installation of some kind of dual-oscillator switching board. My MD1 was 59.36Hz modded to NTSC with the PAL oscillator still in it. I doubt you'd ever notice unless you speedrun, but some displays/scalers apparently have issues with the off-spec refresh rate and can't sync or stutter. I have a VA2 SMS1, I don't even see where the crystal or oscillator is. Maybe it's under the soldered RF-shield? The VA3 boards seem to have the same oscillator as the MD1, that would've been an easy replacement as I still have some NTSC oscillators lying around. Probably doesn't matter, I intend to use the SMS on a CRT that likely doesn't care either way.

I'll see if I can do the RGB bypass and also get csync working. I don't want to spend the money on shielded cables, so avoiding composite video might be a good idea.

edit/btw: RGC sells a cable that just pulls cysnc from an unmodified SMS1. In the comments of the video you linked somebody also points out that the SMS just outputs csync, just like the MD1. So I'm still not sure why we need to rewire anything directly from the CXA.
edit2: Yeah, in video2 he removes all that stuff and just uses the native csync that the console just outputs

[VajSkids Consoles]

Probably what the Dejitter mods are you'll see floating around. To lock in a perfect 60hz for the OSSC etc. have one on the way wish us luck
So far have lucked out on multiple chinese converters, including the one in old mates video in the links... every one that turns up only does composite to HDMI.. Even that one and this was after reflowing the IC's as it didn't work AT ALL inititally. Now it just does nothing with C sync, and when switched to composite as sync just converts the composite and ignores RGB. Also a VC9900 board.. not working. Definitely not the modded systems either as have a stock one chip SNES here and same thing. Either not working, or only converting the composite in SCART to HDMI. That's 4 failed converters from Ebay.

anyway its going back to China for a refund! the VC9900 though I guess is $50 down the drain.

As for the The FM board... for me it was just to sort of "complete" my collection. Went on a mission getting every BIOS revision of the consoles.

So now have model 1 with alex kidd, one with safari hunt, two with Safari hunt + Hang on (selectable) - these model 1 systems are getting really hard to come by

Then with the model 2's literally ended up with 18 of them ... why? Because I also wanted each BIOS revision and because people think the ones with Sonic built in are worth $160+ , well it took until my 18th one to get one with Sonic built in! 17 of them are Alex Kidd. lol some chinese made, a few japanese, one thai, mainly PAL G and B, but the Sonic is Pal-i

Almost all of them were purchased as faulty - and none of them were
Anyway I saw one go for 80 bucks listed as faulty on ebay the other week... so not really worried about my mass collection. Original hardware rocks

again with FM audio The Mega SG has this too ,but I do not like the Mega SG - "Oh it's not an emulator, because FPGA bla bla" + there's not one honest review on them. Yeah, you don't get the software emulator in between the ROM and the hardware, but hardware mimicking other hardware is still emulation to me.

try and play wonder boy III on one, get to the first boss. Have fun with that! the controller input lag is shocking... and there were graphical glitches on this particular game everywhere!

any game requiring precision, super quick reflexes and needing instant response time is a NO!! and that's most games.. I'm sure Enduro racer would be lovely to play as well

Apologies for the RANT, let us know how you go

[ASDR]

I installed the NTSC/PAL switcher yesterday, works great! Instead of a switch I just put a pin header on a ribbon cable in the FM sound compartment and select the mode with a jumper. I was thinking if I install a switch I'd have to desolder it to take the board out again for any jailbar etc. mod.

Next, I'll quickly try to hook up the SMS1 to my shielded csync MD1 cable. If that yields any improvement I'll try to source/build a quality cable for the system. I could just cut off the Mini DIN9 from my MD2 cable and put a regular DIN9 on it. Or I could get a Mini DIN9 socket and a DIN9 plug and build an adapter myself. Would not be to much work and be pretty cheap.

[VajSkids Consoles]

Awesome, i have a bunch out of High quality connexia cables. They are 6 RCA to scart - bidirectional. I used CAT5 and shielded audio cable one of of my model 2’s to a regular 8 pin DIN from jaycar electronics. So obviously female on console end and male on the cable. It just breaks out to 6 RCA females for the cable. I guess I could have just removed the One side of a SCART to SCART cable and bunged the male 8 pin din connector on one end too... another just has 6 RCA jacks on the back. There’s heaps of room. On the sync line I put a switch to to flick between C sync and composite... so you can use composite over SCART or a set of regular RCA leads (yellow, white, red) as I tie the mono together on L/R

I suppose there’s a Million of ways to do it.
I noticed a lot of people install the MD2 DIN output in replacement of the RF on the MD1’s but the original series have an unused DB9 port. You can wire your stereo sound here off the headphone jack along with RGBs and use an ATARI DB9 to scart cable (for modded ataris) which is wired for stereo sound. You’d just have to trace the pins from scart head across to the DB9 end of the Cable and match the wiring on the console end.

Probably need to dremel a bit of plastic out though too as the DB9 port is set back a bit in the hole

[VajSkids Consoles]

Oh of course you’d have to cut the tracks around it first (the DB9) and one pin is tied to ground through opposite side of the board (lots of typos , on me Phone lol )

[ASDR]

I just ordered the appropriate mini DIN / DIN plug & socket from AliExpress to make a short adapter cable. Then I can use the csync MD2 cable I have spare. That's a really cheap solution and leaves the console unmodified. I'll have to wait a month or so for everything to arrive, though :/