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Hi All

I was hunting for more information about SG-1000 board layout etc. and found this Japanese site with schematics and information about the SG-1000 and SC-3000. Very useful information if you're hacking around with the hardware :)

SC-3000 Schematics and Technical Information

http://www2.ODN.ne.jp/~haf09260/Sc3000/EnrSC.htm
*EDIT* http://www43.tok2.com/home/cmpslv/Sc3000/EnrSC.htm

(Translated link)

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

Note - the SG-1000 page from this site was covered in SMS Power back in 2004 - see

http://www.smspower.org/forums/viewtopic.php?t=2483

Unfortunately the mirror links Maxim set up back in 2004 seem to be dead, so I'll repeat the original links here for future reference:

SG-1000 Schematics and Technical Information

http://www2.odn.ne.jp/~haf09260/Sg1000/EnrSG.htm
*EDIT* http://www43.tok2.com/home/cmpslv/Sg1000/EnrSG.htm

(Translated link)

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

...and the Mark III schematics and technical info

http://www2.odn.ne.jp/~haf09260/Mark3/EnrM3.htm
*EDIT* http://www43.tok2.com/home/cmpslv/Mark3/EnrM3.htm

(Translated link)

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

Cheers

This is Enri's website, it is a wonderful resource indeed! Enri sometimes post on our Japanese forum and if you have any question to ask him I could possibly translate it.

I just found a page with info about the 8255 PPI chip
http://www.pci8255.net/8255%20data%20sheet.htm

Hi All

I don't think I've posted this here before - my apologies if I have. But this old thread seems an appropriate place for it anyway.

This is a Sega SC-3000 schematic. It was taken from an old photocopied 'Sega Technical Manual' that a friend of mine has and showed me a few months back. This looks like a resource put together for service personal cobbled together from a various collection of notes and bound up by hand. Most of it is pretty standard information from other resources like photocopied bits of the TMS9929A manual and some excerpts from an early version of Brian Brown's Programmers Manual.

Anyway, the schematic appears to be a Sega original. But unfortunately it looks like a photocopy of a photocopy of an A3 original. So it is very hard to make out. But if you print it on a nice crisp laser or inkjet you can figure most of it out.

It also has the 4095 PAL video daughterboard schematic in there as used in the NZ / Aussie SC-3000s.

Anyway, a couple of people have asked me about schematics recently, so here it is.

http://www.sc3000-multicart.com/images/SC3000_Schematic_600dpi_16color.png

The schematic came up again as someone is trying to fix a broken SC-3000 with a possible broken video daughterboard. The discussion is over here.

http://www.classic-computers.org.nz/forums/viewtopic.php?f=11&t=952

Does anyone know what the big round black component at the top right of the 4095 daughterboard is? (see photo link below). The current theory is that it is some sort of DC - DC voltage level converter. This is required because the LM1889 modulator chip that encodes the video signal has a 12v to 18v supply range, so they couldn't just use a 5v feed off the 7805 voltage regulator to power it. I measured the voltage feed to the ICs on the daughterboard at 11.2v, so that looks about right.

http://www.sc3000-multicart.com/images/SC3000_4095_videoDaughterBoard_cropped.jp...

Cheers

Hi All

A friend of mine made this scan from an A3 schematic of the SC-3000 recently. It also includes the PAL 4095 SC-3000 video daughterboard.

http://www.sc3000-multicart.com/images/SegaSC3000Schematic_A3.jpg

This is the same as the previous schematic I posted, but much clearer as it was off an A3 copy rather than a bad A4 copy of the schematic.

Cheers

This just saved me a lot of trouble ! I was gonna make a schematic myself but this already has the goodies :D

This is fantastic, now we have all the official signal names. The quality is very good too. Thanks!

I guess that funny round thing is a very small transformer. I've never seen one quite like that before.

Charles MacDonald wrote

This is fantastic, now we have all the official signal names. The quality is very good too. Thanks!

I guess that funny round thing is a very small transformer. I've never seen one quite like that before.

No worries. I can't take too much credit for the latest scan though other than posting it :) You can thank Natshaw and Radar from the NZ Classic Computer forums for that scan.

Yes, that funny round thing does appear to be very small transformer. As noted above the video daughter board is fed 9v directly from the incoming supply (rather than 5v from the voltage regulator), and the little round transformer seems to change that to around 11v-12v to feed to the ICs on the daughterboard.

BTW - I think the tolerance on the incoming DC supply is pretty loose as I seem to recall measuring something closer to 10v off one of my power adapters.

Charles MacDonald wrote

This is fantastic, now we have all the official signal names. The quality is very good too. Thanks!

I guess that funny round thing is a very small transformer. I've never seen one quite like that before.

Yeah it is a small transformer, part of a DC-DC voltage converter circuit, to get higher voltage from the standard 9V supply. As HonestBob says, the higher voltage is required for the video chips, specifically the LM1889 video modulator, which needs min 12V to max 18V.

Apologies for bumping an old thread, but it looks like Enri's site has moved once again.

New URL: http://cmpslv2.starfree.jp/

SC-3000: http://cmpslv2.starfree.jp/Sc3000/EnrSC.htm
SG-1000: http://cmpslv2.starfree.jp/Sg1000/EnrSG.htm
Othello: http://cmpslv2.starfree.jp/Fg2000/EnrFG2.htm
Mark III: http://cmpslv2.starfree.jp/Mark3/EnrM3.htm
Master System: http://cmpslv2.starfree.jp/Sms/EnrSms.htm

I am very grateful for Enri for the great reference.

Author	Message
honestbob Joined: 03 Oct 2011 Posts: 188 Location: New Zealand	SC-3000 / SG-1000 schematics and technical details Posted: Fri Nov 18, 2011 2:00 am
	Hi All I was hunting for more information about SG-1000 board layout etc. and found this Japanese site with schematics and information about the SG-1000 and SC-3000. Very useful information if you're hacking around with the hardware :) SC-3000 Schematics and Technical Information http://www2.ODN.ne.jp/~haf09260/Sc3000/EnrSC.htm EDIT http://www43.tok2.com/home/cmpslv/Sc3000/EnrSC.htm (Translated link) http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&... Note - the SG-1000 page from this site was covered in SMS Power back in 2004 - see http://www.smspower.org/forums/viewtopic.php?t=2483 Unfortunately the mirror links Maxim set up back in 2004 seem to be dead, so I'll repeat the original links here for future reference: SG-1000 Schematics and Technical Information http://www2.odn.ne.jp/~haf09260/Sg1000/EnrSG.htm EDIT http://www43.tok2.com/home/cmpslv/Sg1000/EnrSG.htm (Translated link) http://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http%3A%... ...and the Mark III schematics and technical info http://www2.odn.ne.jp/~haf09260/Mark3/EnrM3.htm EDIT http://www43.tok2.com/home/cmpslv/Mark3/EnrM3.htm (Translated link) http://translate.google.com/translate?sl=auto&tl=en&js=n&prev=_t&... Cheers

Bock Site Admin Joined: 08 Jul 2001 Posts: 8653 Location: Paris, France	Posted: Fri Nov 18, 2011 10:06 am
	This is Enri's website, it is a wonderful resource indeed! Enri sometimes post on our Japanese forum and if you have any question to ask him I could possibly translate it.

FluBBa Joined: 21 Jul 2005 Posts: 412 Location: GBG	Posted: Sun Dec 11, 2011 6:24 pm
FluBBa Joined: 21 Jul 2005 Posts: 412 Location: GBG	I just found a page with info about the 8255 PPI chip http://www.pci8255.net/8255%20data%20sheet.htm

honestbob Joined: 03 Oct 2011 Posts: 188 Location: New Zealand	SC-3000 Schematic Scan Posted: Mon Feb 18, 2013 12:34 am
	Hi All I don't think I've posted this here before - my apologies if I have. But this old thread seems an appropriate place for it anyway. This is a Sega SC-3000 schematic. It was taken from an old photocopied 'Sega Technical Manual' that a friend of mine has and showed me a few months back. This looks like a resource put together for service personal cobbled together from a various collection of notes and bound up by hand. Most of it is pretty standard information from other resources like photocopied bits of the TMS9929A manual and some excerpts from an early version of Brian Brown's Programmers Manual. Anyway, the schematic appears to be a Sega original. But unfortunately it looks like a photocopy of a photocopy of an A3 original. So it is very hard to make out. But if you print it on a nice crisp laser or inkjet you can figure most of it out. It also has the 4095 PAL video daughterboard schematic in there as used in the NZ / Aussie SC-3000s. Anyway, a couple of people have asked me about schematics recently, so here it is. http://www.sc3000-multicart.com/images/SC3000_Schematic_600dpi_16color.png The schematic came up again as someone is trying to fix a broken SC-3000 with a possible broken video daughterboard. The discussion is over here. http://www.classic-computers.org.nz/forums/viewtopic.php?f=11&t=952 Does anyone know what the big round black component at the top right of the 4095 daughterboard is? (see photo link below). The current theory is that it is some sort of DC - DC voltage level converter. This is required because the LM1889 modulator chip that encodes the video signal has a 12v to 18v supply range, so they couldn't just use a 5v feed off the 7805 voltage regulator to power it. I measured the voltage feed to the ICs on the daughterboard at 11.2v, so that looks about right. http://www.sc3000-multicart.com/images/SC3000_4095_videoDaughterBoard_cropped.jp... Cheers

honestbob Joined: 03 Oct 2011 Posts: 188 Location: New Zealand	Better quality SC-3000 schematic scan (A3) Posted: Sun Jun 02, 2013 6:08 pm
	Hi All A friend of mine made this scan from an A3 schematic of the SC-3000 recently. It also includes the PAL 4095 SC-3000 video daughterboard. http://www.sc3000-multicart.com/images/SegaSC3000Schematic_A3.jpg This is the same as the previous schematic I posted, but much clearer as it was off an A3 copy rather than a bad A4 copy of the schematic. Cheers

TmEE Joined: 31 Oct 2007 Posts: 853 Location: Estonia, Rapla city	Posted: Sun Jun 02, 2013 7:54 pm
	This just saved me a lot of trouble ! I was gonna make a schematic myself but this already has the goodies :D

Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	Posted: Wed Jun 05, 2013 5:48 pm
Charles MacDonald Joined: 28 Sep 1999 Posts: 1197	This is fantastic, now we have all the official signal names. The quality is very good too. Thanks! I guess that funny round thing is a very small transformer. I've never seen one quite like that before.

honestbob Joined: 03 Oct 2011 Posts: 188 Location: New Zealand	Posted: Thu Jun 06, 2013 3:06 am
	Charles MacDonald wrote This is fantastic, now we have all the official signal names. The quality is very good too. Thanks! I guess that funny round thing is a very small transformer. I've never seen one quite like that before. No worries. I can't take too much credit for the latest scan though other than posting it :) You can thank Natshaw and Radar from the NZ Classic Computer forums for that scan. Yes, that funny round thing does appear to be very small transformer. As noted above the video daughter board is fed 9v directly from the incoming supply (rather than 5v from the voltage regulator), and the little round transformer seems to change that to around 11v-12v to feed to the ICs on the daughterboard. BTW - I think the tolerance on the incoming DC supply is pretty loose as I seem to recall measuring something closer to 10v off one of my power adapters.

natshaw Joined: 17 Feb 2013 Posts: 2	Posted: Wed Sep 25, 2013 11:39 am
natshaw Joined: 17 Feb 2013 Posts: 2	Charles MacDonald wrote This is fantastic, now we have all the official signal names. The quality is very good too. Thanks! I guess that funny round thing is a very small transformer. I've never seen one quite like that before. Yeah it is a small transformer, part of a DC-DC voltage converter circuit, to get higher voltage from the standard 9V supply. As HonestBob says, the higher voltage is required for the video chips, specifically the LM1889 video modulator, which needs min 12V to max 18V.

leadedsolder Joined: 19 Apr 2019 Posts: 19 Location: Canada	Posted: Thu Nov 09, 2023 5:15 am
	Apologies for bumping an old thread, but it looks like Enri's site has moved once again. New URL: http://cmpslv2.starfree.jp/ SC-3000: http://cmpslv2.starfree.jp/Sc3000/EnrSC.htm SG-1000: http://cmpslv2.starfree.jp/Sg1000/EnrSG.htm Othello: http://cmpslv2.starfree.jp/Fg2000/EnrFG2.htm Mark III: http://cmpslv2.starfree.jp/Mark3/EnrM3.htm Master System: http://cmpslv2.starfree.jp/Sms/EnrSms.htm I am very grateful for Enri for the great reference.

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