SE/30 Power supply

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This page details the stock SE/30 power supplies and possible modern alternatives/replacements.

The SE/30 shipped with one of three possible power supply units, manufactured by either Sony, Astec or "Apple Singapore". All three types are universal switching power supplies.

The power supply in the SE and SE/30 is an isolated unit in a metal enclosure which can be removed from the analog board. This differs to the power supplies in the 128K, 512K, Plus and Mac Classic which have a combinated Analog/Power board. The power supply unit in the SE and SE/30 is by far the most reliable of any compact Macintosh.

The SE & SE/30 PSU does not follow any power supply formfactor, it is a custom unit shaped to fit the SE & SE/30 analog board only. It will not fit any other Macintosh other than the SE and SE/30.

There is no fan in the PSU itself; cooling is dependent on the fan mounted on the analog board.

Important: The power supply enclosure is earthed to the SE/30 chassis. The green/yellow earth cable must be securely attached to the bare metal chassis for a good earthed connection.


The SE/30 PSU uses a 10 pin MiniFit Jr connector, part number 5557-10.

Pin Output
1 Ground
2 Ground
3 Ground
4 +5V
5 +12V Disk
6 -12V
7 Ground
8 Ground
9 +5V
10 +12V Sweep

Troubleshooting power supply problems

The following are common symptoms of power-related problems.

  1. The machine fails to turn on via the on/off switch.
  2. and appears to be dead.
  3. The machine overheats and shuts itself down after it is powered on.
  4. A previously working machine unexpectedly freezes or locks up.
  5. Your disk drives don't respond or spin up.
  6. A known good expansion card does not work in an expansion slot.
  7. The machines spontaneously reboots.
  8. Devices that use the external Macintosh ports (such as keyboards)and external disk drives for power don't respond.

Sony CR-44

Apple part No. 699-5047

Sony part No. 68-1074-01

  • AC Input: 100-240V~ 50/60Hz 2-5A max
  • DC Output: +5V 6A, +12V sweep 1.25A, +12V disk 2.1A, -12V 0.5A

The Sony CR-44 is generally considered a well designed and nicely built power supply which seems to have stood the test of time. It is considered to be more reliable than the Astec PSU.

These supplies need to be recapped if yours hasn't been already. The power supply uses various electrolytic capacitors which leak over time, causing erratic behaviour and low voltages. Many of these are still working with their original capacitors as of 2021 but it is only a matter of time until capacitor replacement is inevitable.

Some of these units were manufactured in Taiwan by Taiwan Toyo Radio Co Ltd, others were made in Singapore.

Voltage adjustments can be made in the Sony CR-44 using a potentiometer inside the power supply marked VADJ. This adjustment is something that you may have to do as your machine ages, or when the machine is upgraded with extra boards, disk drives, and so on. Heavily upgraded machines increase the load on the power supply.

Note: When performing voltage adjustments, do not attempt to turn the potentiometer 360 degrees. It will break.

These can sometimes be found used or as new old stock on eBay or other sites. It's useful to have at least one spare in case your unit dies.

Weight: ~1.23kg

Dimensions: 22x11.3x6 cm approx

CR-44 Schematics


Info to come on this soon.

Apple Computer S'pore PTE Ltd

There is a third variant, less common but discussed on the 68kMLA forum.


Modern equivalents/replacements

It is now common to replace the original PSU with a modern ATX formfactor equivalent, because modern power supplies are much more sophisticated and elegant in their design than their older counterparts. Power supply design has made decent progress in the last 30 years. You can now get more output from a smaller unit that runs cooler with less components. A modern power supply will provide strong, stable voltages and it will be much more reliable for long-term usage.

Which power supply should I choose?

Most people seem to choose a Seasonic PSU, there are various models available.


STRATOS SE/30 by Stratos Technology

Max power: 145W +Sweep 20W (45W for sweep with revised models)

DC Output: +5V 14.5A, +12V 3.75A, +12V Sweep 1.5A (3A and 4A in later revisions), -12V 0.5A

I do not know if these are sold anymore or not (most likely not, but I have not contacted Artmix about it), but the Stratos SE/30 is an aftermarket power supply upgrade using the original CR-44 casing but with a new power supply inside it. It was designed for use with upgraded SE/30s to provide stable voltages with large disk drives and accelerators.

After some more resarch, it seems the Stratos SE/30 uses a MeanWell PPT-125B inside with a custom step-up board, using a LT1268 5V to 12V boost converter for the +12V Sweep rail.

Case studies/examples

Eric Bylenga documented how he converted an ATX PSU for use inside an SE.