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  • Joined: 03 Oct 2011
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SG-1000 II - RGB mods and console revisions
Post Posted: Tue Nov 15, 2011 9:36 pm
Last edited by honestbob on Thu Nov 17, 2011 3:57 am; edited 1 time in total
Hi All

I bought a Japanese NTSC SG-1000 II from eBay for testing with the multicart project. But I'm also curious about its video capabilities.

It only has RF output, but it looks like it has solder points for RGB and composite sync output on the PCB. See photos below - quality not brilliant, but blame my cellphone camera for that :)

There is an old SMSPower post from 2004 about how to mod the SG-1000 II to output RGB, but the original link in the post is dead.

http://www.smspower.org/forums/viewtopic.php?t=2323

(original link - dead)
http://www.h5.dion.ne.jp/~baku/RGB/SG-1000II/SG-1000II_RGB.html

Has anyone tried this mod, or did anyone copy and save the original content?




Also does anyone know if there were any SG-1000 IIs released either for PAL systems, or with a composite video connector wired up?

Try plugging this link into microsofttranslator.com

http://baku.homeunix.net/WiKi/rnx/index.rb?cmd=search&word=%23SEGA#a11649825...

The translated link is here
http://www.microsofttranslator.com/bv.aspx?from=ja&to=en&a=http%3A%2F%2F...

About half way down there is a comparison of 'old' and 'new' releases of SG-1000 II. The pictures just show different positioning for the rubber feet. But the second one looks like it has a SCART cable or similar, and the translated text underneath mentions that one version has RGB output and one does not:

Quote
You could screw hole positions, such as in the same Board and enclosure of the old and new is compatible with the shape and seemed cannot decide alone. However, five of SG-1000II obtained so far, exception was. 5 Units in the three way, a new four rubber feet (which can be aRGB output) were two former rubber five feet (non-RGB output).


I also found this page for a SCART cable that says it works for Sega SG1000 II which if true indicates some of them may have had the composite connector wired up

http://fuynfactory.is-a-geek.com/wiki/index.php/Sega_Master_System_-_RGB/SCART

Cheers
SG1000_II_01_smaller.jpg (775.72 KB)
Japanese SG-1000 II
SG1000_II_01_smaller.jpg
SG1000_II_02_smaller.jpg (720.31 KB)
SG-1000 II PCB Top View
SG1000_II_02_smaller.jpg
SG1000_II_03_smaller.jpg (758.99 KB)
SG-1000 II PCB Bottom View
SG1000_II_03_smaller.jpg
SG1000_II_06_smaller.jpg (868.5 KB)
SG-1000 II PCB Bottom Alternate View
SG1000_II_06_smaller.jpg

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Post Posted: Tue Nov 15, 2011 9:59 pm
The dead link has been archived;

http://web.archive.org/web/20040813002401/http://www.h5.dion.ne.jp/~baku/RGB/SG-...

SG-1000 II was only released in Japan and Taiwan, both NTSC countries.
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Post Posted: Tue Nov 15, 2011 10:10 pm
Ok - NTSC only then :) Has anyone seen an SG-1000 II sold with a different video output like the 8 pin DIN connector in on that SCART cable in the link above?

Thanks for that archived link. That gave me enough to search on to find its current actual location (including images - those are missing from the archived copy)

http://baku.homeunix.net/RGB/SG-1000II/SG-1000II_RGB.html

http://translate.google.com/translate?sl=ja&tl=en&js=n&prev=_t&h...



Note - I just read a bit more of some of those translated pages. I'm guessing that the original SG-1000 II releases may have had actual TMS99XX chips, and the second release of SG-1000 II had the custom Sega 315-5066 chip. Can anyone confirm?

eg. from http://dempa.jp/rgb/heaven/g_sg10002.html

http://translate.google.com/translate?hl=en&sl=ja&tl=en&u=http%3A%2F...

Quote
Anyway, SG-I tried to check the contents and then to four Getz Used 1000II. As a result, three chips that are not listed 315-5066 for Sega, but one is listed TMS9918, confirmed that there are two types of the body.


and the baku.homeunix.net mod page above says:

Quote
The SG-1000II and an RGB output can in this way, there are not. RGB output possible if the chip is listed in SEGA, RGB output, if non-listed the TMS9918.
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3 different versions of Aaronix console board
Post Posted: Thu Nov 17, 2011 3:56 am
I found this webpage showing 3 different versions of the Aaronix SG-1000 II clone. If you look really carefully at the second PCB image, that looks like a Texas Instruments symbol on the video chip. The third PCB layout looks very similar to mine (with the custom 315-5066 chip), and is Sega branded. The first one is similar to the second, but the expansion connector isn't wired up.

http://park21.wakwak.com/~suka/sega/kari/sega1000/sega1000.html

So more support for at least two main revisions of the SG-1000 II, one with an actual TMS99XX chip, and one with the custom 315-5066 chip with integrated video and audio (plus extra RGB support).

EDIT - that link has been posted on SMS Power before. I thought it looked familiar. Oops :) You can find out more about the Aaronix releases here.

http://www.smspower.org/forums/viewtopic.php?t=12748
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Confirmed - SG-1000 II with TMS9918A
Post Posted: Mon Jan 09, 2012 9:20 pm
Hi All

Bock very kindly opened up one of his SG-1000 IIs for us and took some photos. There is indeed a version that contains a TMS9918A and seperate VRAM and PSG instead of the integrated 315-5066 chip.

It is interesting comparing the components to both the original SG-1000 and the later SG-1000 II with the 315-5066. It looks like the original SG-1000 II hardware was just a repackaging of the existing SG-1000 Hardware as the main ICs appear identical (just shifted around a bit).

(SG-1000 photos for reference)
http://www.smspower.org/misc/sg1000-01.jpg
http://www.smspower.org/misc/sg1000-02.jpg

The later SG-1000 II revision with the 315-5066 cut out a lot of chips. That drops out the TMS9918A, 8 x 2KB DRAM chips, the sound chip, and a LS32 OR gate and replaces them with the 315-5066 and 2 x 8KB DRAMs. Nice :)

Actually - I'm just assuming the 315-5066 was the later revision, but that makes sense as that is the direction they went with the Mark III and Master System.

So if you're looking for one of these, you need to check the pictures for 5 black rubber feet on the rear. That seems to be enough to identify the older SG-1000 II. I haven't noticed any particular relationship between the serial number and the motherboard layout though.

Cheers
SG1000_II_TMS9918_01.JPG (162.03 KB)
SG-1000 II - 5 black rubber feet on the back
SG1000_II_TMS9918_01.JPG
SG1000_II_TMS9918_02.JPG (1.01 MB)
SG-1000 II with TMS9918A and seperate PSG
SG1000_II_TMS9918_02.JPG
SG1000_II_TMS9918_03.JPG (859.67 KB)
SG-1000 II - close up of TMS9918A
SG1000_II_TMS9918_03.JPG
SG1000_II_TMS9918_04.JPG (876.76 KB)
SG-1000 II - close up of RHS of board
SG1000_II_TMS9918_04.JPG

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Another SG-1000 II RGB Mod link
Post Posted: Sun Jun 16, 2013 1:37 am
Here is an RGB mod for a SG-1000 II with the 315-5066 video / sound chip. I'm planning to try something similar on mine. I've actually done enough background reading to understand the video standards and circuits involved now :) The RF output is awful, and I'm thinking about switching to a different TV which won't tune in the NTSC-J signal, but will have RGB input.

It is a good time to pick up high quality CRT TVs in NZ as they are finally moving to digital transmission, so you can pick up high end 6-8 year old CRTs that look fantastic for less than $20 :)

http://www.nightfallcrew.com/02/09/2012/rgb-synch-amplifier-circuit-for-sega-sg-...

And the Japanese RGB mod link I posted earlier has moved again.

http://baku.homelinux.net/RGB/SG-1000II/SG-1000II_RGB.html

And the translated version is

http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&...

Cheers
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Post Posted: Sun Jun 16, 2013 8:49 am
I wonder if that VDP has a 50/60 selection pin...

This is really cool stuff none the less.
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Post Posted: Sun Jun 16, 2013 6:14 pm
TmEE wrote
I wonder if that VDP has a 50/60 selection pin....


That would be cool :) This is the only information I know of about the pinouts. From memory I checked most of this with a multimeter by continuity testing. Does anyone have any original Sega documentation on this chip?

http://www.smspower.org/forums/viewtopic.php?t=13455

I wonder if you could do it just by changing the oscillator? That is connected to the 315-5066. Thoughts anyone?
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Post Posted: Sun Jun 16, 2013 6:51 pm
Change of oscillator won't change the line count the chip outputs.

I could not notice anything that could act as a 50/60 switch on the pinout, besides NC pins...

What you can try is to take a 1K resistor that is connected to GND and see if any of the NC pins do something. You can also try with VCC. Resistor is necessary not to damage a pin if it happens to be an output.
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Post Posted: Sat Oct 19, 2013 7:03 pm
I just got an SG-1000 II and I bought it without knowing which revision it was. It has the four rubber feet so when I first took a look at it this morning, I assumed it was moddable for RGB. Turns out it's actually the earlier revision with the TMS9918, so I'm thinking the rubber feet count isn't a reliable indicator of which revision it is.

EDIT: Here's one on eBay just like mine; if you look carefully at the motherboard through the bottom vents you'll see the pins for the eight VRAM chips, despite it having the four rubber feet: http://bit.ly/19U2TDE

And here's what looks like an RGB-capable version with *five* rubber feet:
Sega_SG-1000_II_002.jpg (34.17 KB)
Attachment fairy
Sega_SG-1000_II_002.jpg

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