In his latest video, The Bit Culture tackles a Commodore 128D repair, breathing new life into one of Commodore’s most sophisticated 8-bit machines. The project begins with a cautious inspection of the computer’s internals, revealing an improvised PC power supply, dangling wires, and a misaligned disk drive. Rather than rushing to power it up, he carefully replaces the DC supply, reorganizes the wiring, and tests all voltages to confirm the board’s health.
The Commodore 128D was built for professionals, combining the C64 and C128 modes with a built-in 1571 drive. Inside, it features two CPUs—a MOS 8502 running at 2 MHz and a Z80 at 4 MHz for CP/M compatibility—plus an 80-column mode that once made it a favorite for productivity users.
Power Supply Replacement and Testing
The first phase of this Commodore 128D repair involves addressing its unstable power delivery. The original supply had been swapped for a PC unit, which worked but left a messy interior. The Bit Culture replaces it with a clean, efficient Mean Well RD-50A power supply that provides the necessary 5V and 12V outputs. This upgrade eliminates the noise from the old fan while keeping the system cool and stable. After powering on, both the motherboard and disk drive respond perfectly—an encouraging sign.
Drive Alignment and Final Fixes
The second challenge comes from the 1571 drive, which spins up but refuses to read disks written by other systems. Using Free Spirit Software’s alignment utility and a known-good calibration disk, he methodically realigns the read head. A small tilt in the head assembly causes inconsistent reads, but after a few precise adjustments, the drive performs flawlessly across multiple test disks.
With everything reassembled, the Commodore 128D boots cleanly, loads games without error, and runs quietly with its tidy new power configuration.
A Classic Restored
This detailed restoration showcases patience and technical skill in equal measure. The finished computer looks and performs as it should, ready once again to run classic software and games. The Bit Culture’s Commodore 128D repair reminds viewers how rewarding it is to preserve these remarkable machines for future enjoyment.
