External USB-C PD PSU for Atari ST

Replace the original Atari 520ST short power brick

The SidecarTridge External USB-C PD PSU is a complete, fully assembled replacement for the original external brick that shipped with the early Atari 520ST short. A modern USB-C Power Delivery multi-rail board lives inside a custom resin enclosure with rubber feet, terminated through a professionally manufactured cable harness with a 7-pin DIN connector. Plug a USB-C PD charger into one end, plug the DIN into the back of your ST, and you get clean, regulated +5 V, +12 V and -12 V rails. Sized for the Atari ST family and any SidecarTridge add-ons hanging off it, and safer than running a 40-year-old brick with dried-out capacitors.

Ships fully assembled from Spain. For the Atari 520ST short only.

Key features

• Fully external, no case opening: plug the brick into the ST and the USB-C PD charger into the brick. Nothing goes inside the computer. No soldering, no internal modifications.
• USB-C PD multi-rail output: independently regulated +5 V, +12 V and -12 V rails sized for early external-PSU Atari ST models and any expansion hanging off them.
• Purpose-built for Atari rails: built around the proven SidecarTridge USB-C PD Multi-Rail board. No generic USB-C trigger boards or DIY PD adapters.
• Integrated +5 V USB-A output: a regulated +5 V USB-A port on the enclosure powers ACSI2STM, SatanDisk, Gotek and other accessories that cannot be powered from the ST internal lines.
• Pre-assembled 1 m harness: professionally manufactured cable harness, 1 meter long, JST VH 3.96 mm 6-pin on the PSU side, 7-pin DIN on the Atari side. Ready to plug.
• Resin enclosure with rubber feet: custom white resin enclosure, precision manufactured, with pre-installed rubber feet to keep the brick from sliding off the desk.

What's in the kit

• White resin enclosure, precision manufactured, with pre-installed rubber feet.
• SidecarTridge USB-C PD Multi-Rail board, pre-installed and fully wired.
• 1 m cable harness: JST VH 3.96 mm 6-pin on the PSU side, 7-pin DIN on the Atari side.
• 4 x M2 8 mm screws for the enclosure.

Everything ships fully assembled and ready to use. You provide the USB-C PD charger and the USB-C cable.

Installation

1. Get a USB-C PD charger that meets the requirements below.
2. Unplug the old Atari power brick from the wall and from the ST.
3. Plug the new PSU into the ST via the 7-pin DIN connector.
4. Plug the USB-C PD charger into the PSU and into the wall.
5. Power on.

No case opening. No soldering. No internal modifications.

Compatibility

If you are not sure which board your 520ST has, check the silkscreen of the motherboard before ordering.

USB-C PD charger requirements

You bring your own charger. Pick a unit that meets all of the following:

• Power: 45 W minimum.
• Standard: USB-C PD 3.0 compliant. PD 3.1 chargers with Extended Power Range (EPR) may not negotiate correctly even when they advertise PD 3.0 fallback.
• Profiles: must expose both 15 V and 20 V PD profiles. Chargers limited to QC-only or PPS-only are not supported.
• Cable: USB-C cable rated for 45 W or higher. Most USB-C PD cables qualify. You can grab one in our store: USB-C to USB-C cable.

A vetted list of chargers known to work lives in the USB-C PD PSU documentation.

Specs

• Weight: 250 g (assembled).
• Enclosure: white resin with pre-installed rubber feet.
• DC output: +5 V, +12 V, -12 V (Atari ST rails).
• Auxiliary output: regulated +5 V USB-A port on the enclosure.
• Input: USB-C PD 3.0, 45 W minimum, 15 V and 20 V profiles.
• Atari connector: 7-pin DIN, pre-terminated on the supplied 1 m harness.

Frequently asked questions

Which Atari models are supported?
The 520ST short (motherboard revisions C070115 and C070243), which shipped with an external power brick. For the 1040 STF, STFM, STE and Mega ST with an internal PSU bay, the right product is the Internal USB-C PD PSU. Mega STE, TT and Falcon are not supported.

What does the +5 V USB-A output do?
The enclosure exposes a regulated +5 V USB-A port that can power external storage like ACSI2STM, SatanDisk or Gotek without loading the ST internal rails. Keep an eye on total current so you do not exceed the PSU output.

Can the PSU harm my computer?
The PSU is sized for the Atari ST family rails and is safer than a 40-year-old brick running on dried-out capacitors. The risk is in the charger and cable you bring: stick to USB-C PD 3.0 from a reputable brand and a certified USB-C cable.

Do I need to open my Atari to install this?
No. This is a complete external replacement for the original brick. Unplug the old brick, plug this in, done.

Do I need any tools?
No. The cable harness is pre-terminated and the enclosure is pre-assembled. Just a USB-C PD charger and a USB-C cable.

What USB-C PD power adapter do I need?
A 45 W USB-C PD 3.0 charger with both 15 V and 20 V profiles, plus a certified USB-C cable. Most modern laptop and tablet chargers from reputable brands meet these requirements. A vetted list of tested chargers lives in the docs.

Can you recommend a specific charger?
As a supporter of European brands, the Raspberry Pi 45 W USB-C Power Supply is a verified, affordable option that meets every requirement. Any laptop-class USB-C PD charger from a reputable brand that supports the 15 V and 20 V profiles and delivers at least 45 W should also work.

Does it run on PD 3.1 chargers?
Some PD 3.1 chargers with Extended Power Range (EPR) do not negotiate correctly with this board even when they advertise PD 3.0 fallback. Stick to PD 3.0 chargers from the tested list when in doubt.

Good to know

• Drop-in replacement for the original Atari 520ST short external brick. For any Atari with an internal PSU bay, use the Internal USB-C PD PSU instead.
• Homebrew product built for hobbyists, not a sealed appliance.
• You provide the USB-C PD charger and a 45 W-rated USB-C to USB-C cable.

Certifications and compliance

This product is built around the SidecarTridge USB-C PD Multi-Rail power board, which has been assessed for European (CE) and UK (UKCA) conformity. Official Declarations of Conformity and EMC Assessment reports (USBC-PD-PSU REV1.1.0) are available in the documentation.