File:Atari Mega ST Service Manual.pdf

Atari Corporation's Mega Service Manual for the Mega 2 and Mega 4, the machines sold as the Atari Mega ST2 and Mega ST4. The manual is undated; its drawings carry dates from 1986 and 1987. 90 scanned pages with a text layer. Described on Atari Mega ST Service Manual.

Contents, with the printed page numbers:

• Section 1, introduction: main components, case design (figure 2 on p. 1.2 shows the battery compartment), differences from the 520ST/1040ST (p. 1.5).
• Section 2, theory of operation: Glue, memory (1 Mbit × 1 DRAMs, 16 per bank), DMA, MFP, Shifter, Blitter, the RP5C15 real-time clock with its 3 V battery backup (p. 2.7), and the pinouts of the monitor, MIDI, mouse/joystick, printer, RS-232, floppy and hard disk ports (pp. 2.8–2.14).
• Section 3, testing: dead-unit procedure (pp. 3.2–3.3), the Mega/ST diagnostic cartridge revision 4.0 and every test and error code (pp. 3.4–3.19).
• Section 4, disassembly and reassembly (pp. 4.1–4.3).
• Section 5, symptom checklist (pp. 5.1–5.2).
• Section 6, diagnostic flowcharts.
• Section 7, parts list (main board capacitors, resistors, crystals, connectors and ICs with Atari part numbers and locations) and assembly drawings.
• Section 8, schematics and silkscreen: main board, PCB C100167 Rev 5.0 with assembly number CA200019, the ASP34-1 power supply schematic and wiring, and test-fixture drawings.
• Section 9, glossary.

Not included: the main-board schematic sheets are low-resolution and hard to read; the power supply has a schematic but no separate parts list; the later Mega 1 is not covered.

https://archive.org/details/Atari_MegaST_Service_Manual_undated (Internet Archive, uploaded 29 March 2016), retrieved 2026-10-01.

Atari Corporation.

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