Mega CD / Sega CD Schematics - Revision history

Josh: Rewrite from the files: both damaged uploads now open (9 and 5 sheets); identify every sheet and its A4 page in the full manuals; download links for all three; remove em dashes and bold

2026-10-01T08:32:51Z

Rewrite from the files: both damaged uploads now open (9 and 5 sheets); identify every sheet and its A4 page in the full manuals; download links for all three; remove em dashes and bold

← Older revision		Revision as of 09:32, 1 October 2026
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	~~This page holds~~ three A3~~-format~~ Sega Enterprises, Ltd. ~~drawing sets~~ for the [[Sega CD (Model 1)\|Mega CD]] and [[Sega CD (Model 2)\|Mega CD 2]]. ~~They are '''sheets cut from Sega service manuals'''~~, ~~not~~ manuals ~~in themselves~~, and ~~'''two of~~ the ~~three uploads~~ are ~~damaged''' —~~ read ~~the table before planning a repair around them~~.		The '''Mega CD / Sega CD Schematics''' are three sets of A3 drawing sheets from Sega Enterprises, Ltd. service documents for the [[Sega CD (Model 1)\|Mega CD]] and [[Sega CD (Model 2)\|Mega CD 2]]. Each is a large-format scan of pages that also appear, at A4, in one of the complete manuals: the [[Sega CD Service Manual]] for the Model 1, and the [[Sega CD 2 / Mega CD 2 - Service Manual\|Mega CD 2 service manual No. 002]] and its [[Sega CD 2 / Mega CD 2 - Service Manual Supplement\|supplement No. 002-2]] for the Model 2. The larger scans are easier to read at component level. None of the three files has a text layer.

	None of the three ~~carries~~ a text layer.

	== The three files ==		== The three files ==
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	<templatestyles src="Template:StyledTable/styles.css" />		<templatestyles src="Template:StyledTable/styles.css" />
	{\| class="wikitable styled-table" style="width:100%; text-align:left;"		{\| class="wikitable styled-table" style="width:100%; text-align:left;"
	! File !! ~~State~~ !! ~~What is actually on the sheets~~		\|+'''A3 drawing sets'''
			! File !! Sheets !! Contents !! Same pages at A4
	\|-		\|-
	\| [[:File:Mega CD Schematics A3.pdf\|Mega CD Schematics (A3)]] \|\| ~~'''Damaged upload''' —~~ 9 ~~sheets readable, at least one lost~~ \|\| ~~'''~~Mega CD (Model 1)~~'''~~, sheets numbered 67 to 106 ~~of a Sega service manual~~. ~~Internal~~ block ~~diagrams~~ of the ~~Sega custom LSIs — the first sheet is~~ "MAIN BOARD IC2 3/3" ~~for part '''315-5548''' — followed by component-placement drawings~~. ~~The last readable sheet is "'''IC~~ BD MEGA-CD MAIN BD~~'''"~~, ~~Sega part '''~~837-8015-01 (D-~~3/3)'''~~, ~~sub~~-~~assembly '''610~~-~~5266~~-~~01'''~~, ~~dated 1992~~, solder side, ~~'''~~with ~~a value printed~~ against ~~each~~ fitted ~~position'''~~ and ~~several marked NOT USED~~		\| [[:File:Mega CD Schematics A3.pdf\|Mega CD Schematics A3.pdf]] \|\| 9 \|\| Mega CD (Model 1), sheets numbered by hand 67 and 98 to 106. Sheet 67 is the block diagram of the main board's 315-5548 gate array ("MAIN BOARD IC2 3/3"). Sheets 98 to 101 are the main board schematic (PC BD MEGA-CD MAIN BD, assembly 837-8015-01, Sega drawing 171-6105C-01 rev. A, 31 March 1992, four sheets). Sheet 102 is the sub board (837-8046-01, drawing 171-6115C rev. C, 9 December 1991) and sheet 103 the connect board (839-0436, drawing 171-6132C rev. C, 9 December 1991). Sheets 105 and 106 are the main board mount diagrams, component side and solder side, with values against the fitted positions \|\| [[Sega CD Service Manual]], PDF pages 70, 101 to 106, 108 and 109
	\|-		\|-
	\| [[:File:Mega CD 2 Service Manual Schematics A3.pdf\|Mega CD 2 Service Manual Schematics (A3)]] \|\| ~~Intact —~~ 4 ~~sheets~~ \|\| ~~'''~~Mega CD 2~~'''~~, sections 9 to 12 of ~~the~~ service manual: block diagram, schematic ~~diagram~~ 2, main circuit board top and bottom views, and the start of the parts specifications (IC001 hex inverter, IC002 dual D-type flip-flop)		\| [[:File:Mega CD 2 Service Manual Schematics A3.pdf\|Mega CD 2 Service Manual Schematics A3.pdf]] \|\| 4 \|\| Mega CD 2, sections 9 to 12 of service manual No. 002 (August 1993): block diagram, schematic diagrams 1 and 2, main circuit board top and bottom views, and the start of the parts specifications (IC001 hex inverter, IC002 dual D-type flip-flop) \|\| [[Sega CD 2 / Mega CD 2 - Service Manual]], pages 15 to 18
	\|-		\|-
	\| [[:File:Mega CD 2 Supplement Schematics A3.pdf\|Mega CD 2 Supplement Schematics (A3)]] \|\| ~~'''Damaged upload''' —~~ 5 ~~sheets readable, at least one lost~~ \|\| ~~'''~~Sega CD II~~''' schematic section~~, ~~from page~~ 3 ~~onward: "2~~. ~~SCHEMATIC DIAGRAM /~~ 2-1~~. Schematic Diagram-1 [SEGA~~ CD II~~]" — a full component-level main-board schematic showing~~ the ~~Sega custom '''~~315-5632 Ver.ES5~~'''~~, an MC68HC000, an LC89515 and ~~a '''~~315-5476A~~'''~~, with ~~values printed against components~~		\| [[:File:Mega CD 2 Supplement Schematics A3.pdf\|Mega CD 2 Supplement Schematics A3.pdf]] \|\| 5 \|\| Sega CD II and Mega CD II, pages 3 to 12 of supplement No. 002-2 (June 1994), for units from serial number T30282001: schematic diagram 1 (Sega CD II, with the 315-5632 Ver. ES5, MC68HC000, LC89515 and 315-5476A), schematic diagram 2 (Mega CD II), schematic diagram 3 (CD drive, CXD1167Q and CXA1082BQ), main circuit board top and bottom views, and the exploded view with the first page of the parts lists \|\| [[Sega CD 2 / Mega CD 2 - Service Manual Supplement]], pages 3 to 12
	\|}		\|}

	== ~~The damaged uploads~~ ==		== Incomplete files ==

	Two of the three files are '''truncated''': they stop at an exact 4,096-byte boundary partway through an image stream, with no cross-reference table, no trailer and no end-of-file marker. A normal PDF viewer will refuse to open either of them.

	* '''Mega CD Schematics A3.pdf''' — 32,501,760 bytes stored. Nine complete A3 sheets survive; the tenth sheet's image is cut off and is not recoverable from this upload.
	* '''Mega CD 2 Supplement Schematics A3.pdf''' — 35,794,944 bytes stored. Five complete A3 sheets survive; the sixth sheet's image is cut off.

	~~This is~~ an ~~upload fault~~, ~~not a scanning fault —~~ the ~~missing bytes never reached~~ the ~~wiki~~. ~~If a~~ complete ~~copy of either set is found it should replace~~ the ~~file here~~.		The Mega CD file and the Mega CD 2 supplement file were truncated when uploaded, partway through an image, so each ends early: the Mega CD file after sheet 106, the supplement after page 12. The pages that are present are complete. The A4 manuals listed above have the rest.

	== What is not ~~here~~ ==		== What these files do not contain ==

	* ~~'''No parts list~~, no fault ~~tree~~, ~~no disassembly procedure~~, ~~no specifications.''' These are drawing sheets only.~~		* Parts lists, fault-finding charts, adjustment procedures or specifications, apart from the start of the Mega CD 2 supplement's parts list. Those are in the A4 manuals.
	* '''No text layer on any of the ~~three~~'~~'', so nothing~~ in ~~them is searchable~~.		* The Model 1 sub board and connect board mount diagrams, which are in the [[Sega CD Service Manual]] (PDF pages 110 to 112).
	* ~~For a complete~~ Model 1 ~~document see the [[Sega CD Service Manual]]; for the Model 2~~, the [[Sega CD ~~2 / Mega CD 2 - Service Manual]] and its [[Sega CD 2 / Mega CD 2 -~~ Service Manual ~~Supplement\|supplement~~]].

	== Pages that cite this document ==		== Pages that cite this document ==
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	<pdf> File:Mega CD 2 Service Manual Schematics A3.pdf </pdf>		<pdf> File:Mega CD 2 Service Manual Schematics A3.pdf </pdf>

			Downloads: [[:File:Mega CD Schematics A3.pdf\|Mega CD Schematics A3.pdf]] (30.4 MB), [[:File:Mega CD 2 Service Manual Schematics A3.pdf\|Mega CD 2 Service Manual Schematics A3.pdf]] (24.6 MB), [[:File:Mega CD 2 Supplement Schematics A3.pdf\|Mega CD 2 Supplement Schematics A3.pdf]] (30.5 MB)

	[[Category:Sega Schematics]]		[[Category:Sega Schematics]]

Josh: P4 documentation drive: rewrite doc-holder as a real documentation page - title as printed, manual number, issue date, contents with page numbers, honest gaps, and what the document settles; flags two truncated uploads in the Mega CD schematic set

2026-09-25T00:16:43Z

P4 documentation drive: rewrite doc-holder as a real documentation page - title as printed, manual number, issue date, contents with page numbers, honest gaps, and what the document settles; flags two truncated uploads in the Mega CD schematic set

@@ Line 1: / Line 1: @@
-<pdf> File:Mega CD Schematics A3.pdf </pdf>
+This page holds three A3-format Sega Enterprises, Ltd. drawing sets for the [[Sega CD (Model 1)|Mega CD]] and [[Sega CD (Model 2)|Mega CD 2]]. They are '''sheets cut from Sega service manuals''', not manuals in themselves, and '''two of the three uploads are damaged''' — read the table before planning a repair around them.
-A collection of '''Mega CD / Sega CD board schematics''' in A3 format, covering the Mega CD 2 console hardware.
+None of the three carries a text layer.
-== Available Schematics ==
+== The three files ==
-* [[:File:Mega CD Schematics A3.pdf|Mega CD Schematics (A3)]] — Main board schematics
-* [[:File:Mega CD 2 Service Manual Schematics A3.pdf|Mega CD 2 Service Manual Schematics (A3)]] — Service manual schematic pages
+<templatestyles src="Template:StyledTable/styles.css" />
-* [[:File:Mega CD 2 Supplement Schematics A3.pdf|Mega CD 2 Supplement Schematics (A3)]] — Supplementary schematics
+{| class="wikitable styled-table" style="width:100%; text-align:left;"
 [[Category:Sega Schematics]]

Josh: Created Mega CD schematics page

2026-03-26T20:02:40Z

Created Mega CD schematics page

New page

<pdf> File:Mega CD Schematics A3.pdf </pdf>

A collection of '''Mega CD / Sega CD board schematics''' in A3 format, covering the Mega CD 2 console hardware.

== Available Schematics ==
* [[:File:Mega CD Schematics A3.pdf|Mega CD Schematics (A3)]] — Main board schematics
* [[:File:Mega CD 2 Service Manual Schematics A3.pdf|Mega CD 2 Service Manual Schematics (A3)]] — Service manual schematic pages
* [[:File:Mega CD 2 Supplement Schematics A3.pdf|Mega CD 2 Supplement Schematics (A3)]] — Supplementary schematics

[[Category:Sega Schematics]]