Commodore C128DCR internal PSU

Commodore 128DCR internal PSU by Electroware: new internals for your desktop Commodore 128DCR.

An efficient & reliable 120 W replacement power supply to power & preserve. Replaces the original unit and adds peace of mind with Electroware OVP on each rail, precise output voltage trim, advanced low-ripple filtering, easy-to-replace fuses and two auxiliary 5 V/12 V power headers for C128 enhancements or external FDDs.

Stay original! Choose genuine Electroware and beware of overrated clones flooding eBay & the web.

Commodore 128DCR internal PSU: THE NEW POWER TO GET READY AGAIN.

Based on our experience with the well-known Commodore 128 external PSU, we designed this unit to deliver 10 A @ 5 VDC, 5 A @ 12 VDC and 1.5 A @ 9 VAC—around 120 W total. You won’t use all that headroom, but running at ~50% load means lower electrical noise, reduced heat and longer component life. Standard features include independent OVP for both 5 V and 12 V rails, safe-range 5 V/12 V trimming for upgraded systems, easy 5×20 mm fuses and two universal connectors (5 VDC & 12 VDC) to power devices like 1541-II/1581 (with suitable cable), Ultimate-II+, fans or other peripherals.

C128DCR computers shipped with two internal PSU variants (see photos). The switching-mode Mitsumi 68-4224A is well built but no longer meets modern expectations. The Commodore “8708” is a more economical, transformer-based design that runs hot and often produces an audible hum that can resonate through the desk.

Both original PSUs can be recapped, repaired (the 8708’s AC input wiring often needs attention) or upgraded—but even then, 30–40-year-old electronics can fail without warning, and damage to the C128 main board can be severe (remember: the PSU also powers the 1571 FDD).

If your original Commodore 128DCR PSU is no longer working—or you’re unsure of its health—it’s time for a high-quality replacement power supply. With modern enhancements like Ultimate-II+ and additional peripherals, load and thermal stress increase; an overloaded original supply becomes a real risk.

To install, retain the original mounting plate, screws, power switch and AC connector as shown. Our replacement swaps the electronics board and output cabling only. Because this PSU provides a true 9 VAC via a real transformer (as per original), choose the correct input version: 230 VAC (Europe) or 115 VAC (USA/Canada/Japan).

This replacement PSU is compatible with the Commodore 128D-CR (metal case, “cost-reduced”) but not with the earlier 128D (plastic case with handle/keyboard bay; not originally sold in the USA). To control cost and preserve the look, we re-use the factory plates, runners, shields, AC inlet and power switch (easy to extract). Safety first: mains AC is dangerous—always work with the power cord unplugged, and do not connect or power on until everything is fully mounted, double-checked and shielded.

The voltage trim potentiometers are on the low-voltage side, but access requires the machine to run with the enclosure open. High-voltage areas are insulated, yet you must proceed with extreme caution—use an insulated screwdriver and protective gloves.

UNIQUE FEATURES & QUALITY

• Commodore C128DCR compatible (metal desktop case)
• Stabilized & filtered 5 VDC up to 10 A
• Stabilized & filtered 12 VDC up to 5 A
• 9 VAC up to 1.5 A via real, heavy-duty transformer
• Active & passive OVP on both 5 V & 12 V rails
• OCP (over-current protection) on all outputs
• Voltage spike suppression with ultra-fast TVS diodes
• Protected 5 V and 12 V trimmers for safe fine tuning
• Fully isolated & fused on AC and DC sides
• Easy-to-replace, standard 5×20 mm fuses
• Two auxiliary power ports for 5 VDC and 12 VDC (with resettable fuses)
• Optional 0.5 m auxiliary cables (5 V/12 V) with Wago fasteners for quick connection
• 115 VAC (USA) or 230 VAC (Europe) input versions
• “Power-good” status LEDs for 5 VDC, 12 VDC and 9 VAC
• Advanced low-ripple filtering for clean rails
• Detachable C128DCR output power cable for easier installation (included)
• 100% repairable; service-friendly design; spare parts available
• Industrial, detachable wire-to-board connectors—no unsafe direct-soldered AC/DC leads

INSTALLATION TIPS:

Always work with the AC cable unplugged, and reconnect only after all shields and covers are back in place.

Always connect the green/yellow ground wire securely to the metal shield.

Where possible, desolder the original AC_L and AC_N from the old PSU PCB rather than cutting. If cutting is unavoidable, cut close to the PCB and tin the wire ends (or twist firmly). The new AC terminal block accepts the original copper leads—no soldering required. After mounting, secure the AC/L and AC/N connections and add a zip tie as strain relief.

Both old and new PSUs contain high-capacitance parts on the high-voltage input. Allow time to discharge before installation/removal. Keep the output cable connected to the C128D main board as long as possible to aid discharge. Wait 30–60 minutes after power-off and unplugging. For safety, do not touch the PCB underside; handle by the mounting holes and edges.

Our output cable uses the original Commodore color code. Confirm polarity on the C128 PCB before connecting. Refer to the installation photos and your stock assembly for orientation.

Color codes for the provided output cable:

• white/brown: 9 VAC
• black: GND
• red: 5 VDC
• yellow: 12 VDC

TRUST & RESPONSIBILITY

Every Electroware PSU is triple-tested before dispatch. We validate with original C128DCR hardware from our collection and perform burn-in against custom loads up to ~150% of a typical C128DCR system to verify thermal margins and protection response.

Choose genuine Electroware for build quality and features that clones don’t match. 

By purchasing this product you support the retro computing community and our ongoing development. Thank you!

WARNING!

Disconnect the main AC power cord before installing or removing PSU units. Always use the ground connection and refit all shields/covers to avoid electric shock. Wait at least one hour for AC capacitors to discharge before attempting disassembly.

Risk of electric shock and energy hazard. Service should be performed by qualified technicians only. Protect ventilation openings from foreign objects and moisture. Do not install near heat sources, or in high-temperature, dusty or damp locations. Indoor use only. Do not exceed rated output current or wattage.

This replacement Commodore 128DCR PSU is designed as a component of the Commodore C128DCR system only; do not use with other devices. The manufacturer is not responsible for damage resulting from unauthorized repairs, modifications or misuse. A new, properly functioning PSU reduces failure risk but cannot guarantee overall health of a 30–40-year-old system.

Stay original! Choose genuine C64PSU.com gear and beware of overrated clones.