Editing Macintosh SE/30 Logic Board Schematic

<pdf> File:Macintosh SE30 Logic Board Schematic Redraw 050-0253-01.pdf </pdf>

The complete circuit diagram for the '''[[Macintosh SE/30]]''' main logic board — a ten-sheet KiCad redrawing of Apple engineering drawing '''050-0253-01''', made by the ''macse30mlb'' project and dated 26 July 2022. Apple's own scans of 050-0253-01 are barely legible; this redraw is the practical reference for anyone tracing a fault on an SE/30 board, and Recap-a-Mac recommends it for exactly that purpose.

It is released under the MIT licence, which is why it can be hosted here rather than merely linked.

== What is on each sheet ==

* '''CPU + FPU''' — the 68030 at UK8 and the 68882 socket at UI5, with the reset, halt and bus-error signals.
* '''GLUE + RAM SIMMs''' — the glue logic chip UI8, the RAM signal PAL UH7 and the SIMM sockets.
* '''ROM + RAM Muxes''' — the ROM SIMM connector and the F258 multiplexers above it.
* '''Video Interface''' — the video RAM, the video IC UK6 and the Ux8 multiplexer row.
* '''VIA1 + VIA2 + RTC + ADB''' — UK12, UK11, the real-time clock with its 32.768&nbsp;kHz crystal Y1, and the ADB transceiver UL11.
* '''SWIM + SCSI Interface''' — the SWIM floppy controller UJ11 and the NCR 53C80 SCSI controller UI12.
* '''Serial Interface + Sound Interface''' — the line drivers UD12 and UE12, the Apple Sound Chip UE10 and the Sony sound chip UB11, with the 16.9344&nbsp;MHz crystal Y3.
* '''Power Connector + Pullups + Pulldowns''' — connector '''J12''', the "Power &amp; Video Connector", plus the pull-up packs RP7, RP8 and RP9 and the 1&nbsp;A fuse F1.

== Why it matters for repair ==

Sheet 9 gives the J12 pinout, which is what makes it possible to bench-power a bare SE/30 logic board without guessing: pins 1–5 and 8 are ground, pin 6 is −5&nbsp;V, pin 7 is −12&nbsp;V, pins 9, 10 and 11 are video out, horizontal sync and vertical sync, pins 12 and 13 are +5&nbsp;V and pin 14 is +12&nbsp;V. Getting that wrong on a bench supply destroys a board.

The same sheet identifies fuse '''F1''' as a 1&nbsp;A part — the usual reason an otherwise healthy SE/30 has a dead keyboard and mouse — and gives the pull-up pack values, including RP7 at 1&nbsp;kΩ, which pulls up !BERR.

Download the schematic here: [[:File:Macintosh SE30 Logic Board Schematic Redraw 050-0253-01.pdf]]

== Related Pages ==

* [[Macintosh SE/30]]
* [[Macintosh SE/30 Troubleshooting]]
* [[Macintosh SE/30 Capacitor Replacement Guide]]
* [[Macintosh SE/30 General Maintenance]]
* [[Sad Mac Error Codes]]

[[Category:Apple Schematics]]
[[Category:Apple Vintage Computers]]