In simple terms, a PFC circuit makes an electronic device "look" like a simple resistor to the mains power grid. Without it, the current drawn from the wall outlet can be out of phase with the voltage, creating "harmonics" that waste energy and interfere with other equipment on the same circuit. The R2A20112 is designed to correct this, ensuring high efficiency and compliance with international power quality standards.
If you are restoring an older device featuring the A20112 topology, consider executing a few strategic component upgrades to improve reliability and thermal performance: Replace original 85∘C85 raised to the composed with power C rated electrolytic capacitors with high-quality, low-ESR 105∘C105 raised to the composed with power C
, lock the voltage at a precise, stable level regardless of load changes. The Investigation: Following the Schematic
: Restores power when a printer fails to turn on, shows error codes, or exhibits unstable performance. Service Manual a20112 power supply schematic
A common-mode choke inductor paired with X and Y-rated safety capacitors suppresses high-frequency line noise. Stage 2: Step-Down Transformer
Silicon diodes like the standard or high-current 1N5408 series are commonly designated here to handle rectification stresses. Stage 4: Bulk Filtering
: Protects the circuit from power line spikes . In simple terms, a PFC circuit makes an
Often, the best place to start is the official website of the power supply's manufacturer. Companies like Meanwell, Delta, or Eaton usually provide datasheets and technical documentation for their products, which may include schematics or block diagrams.
: Rectifies the high-frequency AC back to DC and uses feedback loops to maintain a constant output (e.g., 12V or 24V). Useful Technical Resources Circuit Walkthroughs : For a deep dive into the electronics, Instructables
In a standard schematic, such as those found on Scribd , the R2A20112 is positioned in the "hot" (primary) side of the circuit. Circuit Stage Primary Components Involved Fuses, Inductors (L102), X/Y Capacitors Removes high-frequency noise from the AC line. Bridge Rectifier 4-Diode Bridge (D101) Converts AC input to pulsating DC. PFC Stage R2A20112 IC , Boost Inductor, MOSFETs Corrects the power factor and boosts voltage to ~400V DC. Secondary Outputs Transformers, Regulators (7805/7812) Provides regulated +15V, +12V, or +5V for the device. Common Repair and Troubleshooting Tips If you are restoring an older device featuring
: Uses a series of high-voltage electrolytic capacitors (e.g., 22uF to 47uF rated at 450V+) and often a choke or large power resistors to smooth the DC voltage. Switching Options : Some versions include a 7W/14W power switch
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 blown, check for a shorted bridge rectifier or a shorted primary pass transistor before replacing it.
The A20112 utilizes either four discrete high-speed diodes or a single integrated bridge rectifier block. This stage flips the negative halves of the AC sine wave into positive pulses, resulting in pulsating DC. 3. Smoothing and Filtering Stage