SCSI2SD HDD Emulator – DIY

Big problem with vintage Macintosh computers today is that their hard drives are very likely to fail. Especially SCSI drives mounted in Powerbooks are very quickly becoming extinct.

One on the popular modern SCSI drive emulators is SCSI2SD from codesrc. I have one of those drives and find it reliable. The problem is that I have more than 10 machines in need of drive replacement. SCSI2SD costs about $60 for 3.5″ version and $80 for 2.5″ Powerbook edition. I think it is a bit too expensive given the large quantity of drives in need and comparable prices of the machines that await resurrection.

SCSI2SD Kit for Home Assembly

I started looking for an alternative and found a competitive project that rebuilt SCSI2SD drive as a kit suitable for home amateur assembly. It is possible to purchase PCB only for $8, which should minimise the cost of the drive. All the firmware and software is identical with the older version of the SCSI2SD project, which fortunately licenses them under GPL, enabling free reuse. Codesrc page indicates that the SCSI2SD design has been updated since and older version may be missing features or not work on all machines. I found out however, that it is good enough to restore Powerbook machines.

Robert Matyschok Electronics Trade and Consulting offers two versions of the PCB for purchase.

  • Version 1.0 has the MicroSD card adapter placed in a way that needs desoldering and changing the position of the adapter’s header pins. It is however $1 cheaper than version 1.1.
  • Version 1.1 has the MicroSD card adapter orientation corrected, so it can be more easily attached to the PCB. It costs $9.

Here are pictures of Powerbook 180c and Powerbook 140 with the SCSI2SD drives mounted.

BOM

The cost of the complete build is the following:

ComponentSourcePriceComment
PCBeltradec.eu$8Version 1.0
CY8CKIT-059farnell.com$20Probably can find as cheap as $10
SN74LVC06ADfarnell.com$0.35*3Inverting buffer
MF-NSMF150-2farnell.com$0.5Fuse
4610X-101-101LFfarnell.com$0.4*2SCSI terminator resistor packs
LD1117ADT-TRfarnell.com$0.6Adjustable voltage regulator
B360A-13-Ffarnell.com$0.25Diode
100nF/50VLocal shop$0.02*4SMD capacitor
10uF/25VLocal shop$0.5SMD capacitor
240RLocal shop$0.01SMD resistor
300RLocal shop$0.01SMD resistor
40pin angle header 2mm rasterInternet auction$0.70Expensive in other shops
26pin straight headerLocal shop$0.50*2
TOTAL$33.5

Tutorial on the Build Process

PART 1 – Preparing CY8CKIT-059 Board

This part describes how to program CY8CKIT-059 microcontroller board and prepare it for mounting on the SCSI2SD PCB.

Resources used:

Part 2 – Soldering SCSI2SD Components

This part shows how to solder components on the SCSI2SD PCB step by step.

Part 3 – Configuring SCSI2SD Board

This part shows how to configure SCSI2SD board for use in a Powerbook machine with Mac System 7.5.x and 1GB SD card. OS images for download and instructions how to prepare the SD card can be found on a David’s and Steve blog. Using the drive in other machines, with other card sizes and other OS versions may require different settings.

Part 4 – Mounting SCSI2SD in Apple Powerbook 140

This example shows how to effectively mount SCSI2SD board instead of a built in HDD in an Apple Powerbook 140 machine and it demonstrates booting the OS.

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