Repurpose Sega Master System RGB upscaler to MSX

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By wbahnassi

Expert (118)

wbahnassi's picture

29-05-2020, 00:36

I'm wondering if I can take this RAD2X cable built for the Sega MasterSystem and rewire the connector to MSX RGB 8-pin Din. I think the pin out has the same signals except that MSX uses C-sync instead of Sega's separated composite and sync lines. Would it be a problem if I connect MSXs C-sync as Sega's Sync?

This is the MasterSystem RGB pinout:

And the MSX pinout is the officia DIN 45326 type A with C-sync at pin 4 in our wiki.

Cheers!

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By sdsnatcher73

Paragon (1136)

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29-05-2020, 12:33

The MSX sync is the same as genesis pin 1 (except for the turbo R which outputs composite video and thus introduced jail bars on RGB). As long as the RAD2X does not depend on the composite signal (I don’t think it will) you should be good to go!

By wbahnassi

Expert (118)

wbahnassi's picture

29-05-2020, 21:39

Thanks for confirming sdnatcher! Will go for it then. It's out of stock currently but should become available soon. Will let you know how it goes!

By sdsnatcher73

Paragon (1136)

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29-05-2020, 21:57

You could build a male to female DIN adapter with a short cable that on the male side has MSX pin layout and on the female side has the MD layout. That way you would not have to modify the RAD2X cable (and if it does not work you may send it back or resell).

By Pentarou

Champion (285)

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30-05-2020, 07:17

sdsnatcher73 wrote:

The MSX sync is the same as genesis pin 1

Are you sure about that? SMS/MD Csync is TTL level (5v), but Csync on MSX seems to be 0.7/0.8V or 1.8V.

Moreover, proper SMS/MD RGB cables have 75R + 220uF in series on R/G/B lines, which may be not needed on MSX.

By Emphy

Resident (43)

Emphy's picture

30-05-2020, 09:26

Not sure if this would be a potential problem or not: note that, since the rad2x is based on the retrotink2x, it also has to get its power through the connector somehow. You may want to double check whether the msx can provide this power without problems and that it is at the right pin.

By Pencioner

Scribe (1170)

Pencioner's picture

30-05-2020, 12:29

retrotink2x has power from micro-usb

EDIT: oh, i got what you mean, is that rad2x cable having retrotink inside? then it might be an issue... the DIN8 output of Japanese MSX models doesn't have any +5 or +12 power pins...

By wbahnassi

Expert (118)

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30-05-2020, 13:53

I'm planning to use it with an Arabic MSX that has the standard RGB pinout as shown in our wiki. According to that, there is slow switch (pin 3) that is rated at +5V and the fast switch (pin 5) which is +12V. So I'm guessing pin 3 from MSX RGB goes to pin 5 on SMS so that Rad2x gets its power, and hope the MSX is powerful enough to give it the needed amps. Does that even make sense?

Csync on this MSX model is 1.8V according to our wiki. Would that fall below the level that Rad2x needs to detect the signal?

By sd_snatcher

Prophet (3348)

sd_snatcher's picture

30-05-2020, 15:16

You would have to mod the rad2x to remove the 75R series resistors from its RGB inputs. You can also remove the respective series capacitor, but it's not mandatory.
Note: Do not remove the 75R resistors it probably has from the RGB lines to the GND. Those are required.

For the CSYNC, the original retroTINK is SCART compliant, so it probably accepts 0.3Vpp CSYNC like the MSX outputs. But you'll have to analyse how the rad2x converted the TTL CSYNC of the Megadrive to the 0.3Vpp level used by the retroTINK SCART input and make the necessary adjustments.

By Pencioner

Scribe (1170)

Pencioner's picture

30-05-2020, 15:36

wbahnassi wrote:

I'm planning to use it with an Arabic MSX that has the standard RGB pinout as shown in our wiki. According to that, there is slow switch (pin 3) that is rated at +5V and the fast switch (pin 5) which is +12V. So I'm guessing pin 3 from MSX RGB goes to pin 5 on SMS so that Rad2x gets its power, and hope the MSX is powerful enough to give it the needed amps. Does that even make sense?

Last time i used pinout for making an DIN8 to SCART cable back in 2015 i used this MSXFAQ article and it has some different information. So it might work or might not (and remark 'Shouldn't be used as Vcc' in there would make me think twice btw). But if that info is incorrect, and our wiki is correct, than it is fine of course, just check it twice (maybe looking to some available circuits of those Yamaha/Sakhr models would help understanding)

By sdsnatcher73

Paragon (1136)

sdsnatcher73's picture

30-05-2020, 16:04

sd_snatcher wrote:

You would have to mod the rad2x to remove the 75R series resistors from its RGB inputs. You can also remove the respective series capacitor, but it's not mandatory.
Note: Do not remove the 75R resistors it probably has from the RGB lines to the GND. Those are required.

For the CSYNC, the original retroTINK is SCART compliant, so it probably accepts 0.3Vpp CSYNC like the MSX outputs. But you'll have to analyse how the rad2x converted the TTL CSYNC of the Megadrive to the 0.3Vpp level used by the retroTINK SCART input and make the necessary adjustments.

The retrotink is YPbPr not SCART compliant, the RAD2X does an extra RGB to YPbPr conversion. I’ve checked different sites and they all report MD has composite video, not sync. Either way the RGB to YPbPr conversion should accept the MSX’s sync signal imho. Also if an MD1 (with a 8.5W PSU) can power the RAD2X surely an MSX can too. I would still start with a conversion cable from MSX pinout in male connector and MD1 pinout in female connector and see what gives. The termination 75 ohm resistors in a MD cable are the only thing I am not sure about. Would they really be present in the RAD2X (they are for terminating towards a 75ohm monitor but the converter may still require it as well). Are the MSX RGB signals already 75ohm terminated?

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