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Sega Master System II Service Manual (1991)

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The Sega Master System II Service Manual is Sega Enterprises, Ltd.'s service manual for the Sega Master System II, dated April 1991 and issued by the company's Overseas Consumer Products Division. It covers the PAL boards and the French RGB board. The hosted scan has 26 PDF pages and a searchable text layer.

Contents

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The scan does not follow the printed page order: the parts lists come before the schematics, and the RGB schematic is missing. The PDF page for each section is given here so that citations can point at the right place.

Section Printed page PDF page
Product number and colour specifications; AC adaptor specifications 1 3
Product dimensions and weight; electrical specifications 2 4
Flowchart for troubleshooting fault locations 3 5
Servicing the main unit (test procedures) 4–5 6–7
Possible symptoms for each fault location 6 8
Picture without sound; no picture 7 9
Controls do not respond normally 8 10
Software (card or cartridge) malfunctions 9 11
Auto switchboxes; controller related 10 12
Schematic diagram, PAL version (171-5922A, three sheets) 11–13 18–20
PCB parts location diagram, PAL version 14–18 21–25
Parts list, PAL version 19–21 13–15
Schematic diagram, RGB version 22–23 not in this scan (see below)
PCB parts location diagram, RGB version 24 26
Parts list, RGB version 25–26 16–17

What it covers

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The parts lists cover two boards: 171-5922A ("PC BD M4JR PAL") and 171-5926A ("PC BD M4JR VA1"), the RGB board for France. The five PAL parts-location drawings are the regional assemblies PAL-B (VV) 837-7370, PAL-G 837-7367, PAL-B (VE) 837-7371, PAL-D 837-7559 and PAL-I 837-7369; the RGB drawing is 837-7560.

Page 1 lists the model numbers by territory (MK-3006 for America, MK-3006-09 for France, MK-3006-18 for Germany and others) with the RF modulator part and channel for each, and the AC adaptor part numbers. The parts lists give a further set of adaptors: 400-5126 (Europe), 400-5129 (UK) and 400-5130 (Australia), all DC 9 V 0.5 A, and 400-5048Y (DC 9 V 1 A) for the RGB version.

The repair procedures give go/no-go figures: DC 9 V in and DC 5 V out at the 7805 regulator (IC8); 0 to 3.6 V rising slowly at reset test point JR, with C18 and R4 named as the parts to check; 10.738635 MHz ±100 Hz at IC4 pin 41; 3.579545 MHz ±30 Hz at IC5 pin 33; 4.43361875 MHz ±30 Hz at IC4 pin 42; and audio of up to 300 mVp-p from IC5 pin 15. The software section suggests a 100–180 pF capacitor on address line A13 as a cure for resets in the middle of a game.

The parts lists use one interleaved C sequence that contains both ceramics and electrolytics, plus a separate CE1–CE6 block of 10 µF 16 V electrolytics. On the PAL board the electrolytics are C18, C31, C32, C38, C41, C42, C43, C44 and CE1–CE6. CP1–CP13 are 0.022 µF ceramics. Sega's part numbers mark the type: 150-xxxx for electrolytics and 151-xxxx for ceramics, and the description column says CAP E or CAP CER.

What it does not contain

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  • The RGB schematic (printed pages 22–23) is not in this scan. One sheet of it, "IC BD M4 Jr. RGB" 171-5926, is bound into the hosted scan of the Sega Master System Service Manual (1986) as its PDF page 13.
  • There is no NTSC board: the manual covers the PAL and French RGB versions only, although some of its test figures (10.738635 MHz, 3.579545 MHz) are NTSC values.
  • There is no disassembly procedure and no theory of operation.
  • It does not cover later boards such as 171-6395A or 837-7275.
  • It does not cover the original Master System; see the Sega Master System Service Manual (1986).

Pages that cite this document

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Download: Sega Master System II Service Manual April 1991.pdf

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