A20112 Power: Supply Schematic

Without the exact turns ratio, repair is guesswork. Based on reverse-engineering an A20112-3A unit:

Critical note: If the transformer is shorted, the schematic won’t help – you will need to rewind or replace the module. A ring tester is essential.

Recommended architecture for mains-powered design: a20112 power supply schematic

For a DC-input (24–36V) non-isolated buck converter:

Based on the physical inspection of the PCB, the A20112 follows a standard Flyback Converter topology with multiple isolated outputs. Without the exact turns ratio, repair is guesswork

The A20112 is a switch-mode power supply (SMPS) designed for the Namco System 246 and 256 arcade motherboards. Unlike standard PC ATX power supplies, the A20112 utilizes a custom form factor and a dedicated single-row output connector to interface directly with the arcade I/O board. It is a high-efficiency unit capable of delivering substantial current on the +12V rail to power the console's cooling fans and disc drives, while maintaining stable low-ripple voltage for the sensitive CPU and RAM (+3.3V and +5V).

The A20112 is typically a compact switching power supply module. While often associated with specific proprietary industrial systems, these units generally follow standard switch-mode power supply (SMPS) topologies. Critical note: If the transformer is shorted, the

They are designed to take a high-voltage AC input (often 110V/220V) and convert it into stable low-voltage DC output (commonly +5V, +12V, or +24V rails).

Operation: When the MOSFET is on, energy is stored in the transformer core. When the MOSFET turns off, the energy is released to the secondary side.

Important: Adjust the overvoltage protection (OVP) on the secondary Zener diode (ZD2). If it’s rated 15V, change it to 18V.