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Repair guide

Replace a dead SCSI hard drive with a SCSI2SD or ZuluSCSI

A SCSI2SD or ZuluSCSI board presents an SD card to the Mac as a SCSI drive. It is a practical way to bring a vintage SCSI Mac back to life without hunting for scarce old drives.

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Drive · Medium · about 90 minutes. Worth doing. Reports say this fix helps on many machines.

You are in the right place if: The Mac clicks, will not spin up, or never mounts its hard drive, and you want a silent replacement.

Before you start

  • Compact Macs contain a CRT with dangerous stored voltage. Do not open past the logic board area.
  • Unplug before opening and handle power connectors with care.

Board revisions and models

Connector type and SCSI ID differ between models. Check your Mac's SCSI notes.

Parts you may need

Tools

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Step by step

  1. Back up what you can If the old drive still mounts, copy data off first.
  2. Choose a SCSI emulator Buy a SCSI2SD or ZuluSCSI that matches your machine's connector.
  3. Prepare the SD card Format the SD card and set up the device ID and size using the board's utility.
  4. Install a system image Prepare a bootable system image for your Mac model and copy it to the card.
  5. Power off and open the Mac Unplug and open the case up to the drive bay only.
  6. Remove the old drive Disconnect SCSI and power cables and unscrew the drive.
  7. Fit the emulator Mount the board with brackets, connect SCSI and power, and set the ID.
  8. Check termination Make sure the SCSI chain has termination where required.
  9. Boot and test Power on, boot the Mac and check the emulated volume mounts.

Tips, tales and maybes

Found in write-ups and forum threads. These are other people's reports, not tested by us.

  • Maybe (Low confidence). Make a copy of your SD card image once it works so a bad card does not cost you a clean install. General technique, no source.

Manuals and technical documents

Service manuals, schematics and datasheets for this machine, kept in our own library. Check your own board and part numbers against them.

Mac 128K, 512K, Plus and SE analog board

All 4 documents for Mac 128K, 512K, Plus and SE analog board in the library

Macintosh Classic and Classic II

All 1 documents for Macintosh Classic and Classic II in the library

Macintosh II

All 2 documents for Macintosh II in the library

Macintosh IIci and IIsi

All 1 documents for Macintosh IIci and IIsi in the library

Macintosh Quadra 700 and 900

All 2 documents for Macintosh Quadra 700 and 900 in the library

Sources

We wrote this one from general technique and have no source to credit for it yet. Treat it as a starting point, and read or watch a guide for your exact model before you begin.

Boards and models vary, so check what is in front of you. A repair can involve hot tools, chemicals and, on some machines, dangerous voltages. You do it at your own risk.

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