If your output is significantly lower than spec (e.g., reading 7V on a 12V rail), check for shorted output rectifiers or failing smoothing capacitors. Safety Warning:
As these units age (most manufactured between 2000–2005), specific components are prone to failure. a20112 power supply schematic
When dealing with a board using the A20112, failures often occur in the peripheral components rather than the IC itself. 12V Power Supply Repair If your output is significantly lower than spec (e
A20112 Power Supply Schematic — Detailed Design, Analysis, and Implementation reading 7V on a 12V rail)