A20112 Power Supply Schematic Jun 2026
To successfully decode, design, or repair an A20112-based system, one must understand how power transitions sequentially through the board. The standard schematic layout breaks down into several functional zones: 1. Input Protection and EMI Filtering
These are simpler, more reliable, and produce less electrical noise, making them ideal for low-power requirements or sensitive audio equipment.
Before the current reaches the output headers, it undergoes a final conditioning phase.
Are you trying to or trying to clone the circuit ? a20112 power supply schematic
| Component | Value | Specification | | --- | --- | --- | | C1, C2 | 10uF, 22uF | 250V, 20% | | L1 | 10uH | 10A, 20% | | D1-D4 | 1N5408 | 1000V, 3A | | Q1 | IRF840 | 500V, 8A | | T1 | 10:1 | 1000V, 10A | | D5 | 1N5822 | 40V, 10A | | C3, C4 | 100uF, 220uF | 25V, 20% | | L2 | 10uH | 10A, 20% |
: Commonly found in LED TV power boards, industrial power modules, and large-screen monitor power supplies (e.g., iMac 27-inch units often use similar high-power designs) . Key Features :
This public link is valid for 7 days and shares a thread, including any personal information you added. This link or copies made by others cannot be deleted. If you share with third parties, their policies apply. Can’t copy the link right now. Try again later. To successfully decode, design, or repair an A20112-based
Controlled by the A20112 to regulate the energy flow.
Measure voltage across C4 (VCC pin of PWM IC). It should rise to 12–18V. If it stays below 10V, replace C4 and check R5 (startup resistor). If still low, the PWM IC may be shorted.
| Symptom | Likely Fault (per schematic) | Diagnostic Step | |---------|-------------------------------|-----------------| | No output, fuse blown | Shorted MOSFET (Q1) or bridge rectifier | Check diode mode across drain-source of MOSFET. Replace both MOSFET and current sense resistor. | | Output cycles on/off (ticking sound) | Overcurrent protection active | Check secondary Schottky diode (short) or output capacitor (high ESR). Measure CS pin voltage – should be <1V. | | Output present but drops under load | Failed bulk capacitor (C5, 400V) | The capacitance drops below 50µF. Replace with 105°C rated Lelon or Nichicon. | | Very low output (e.g., 3V) | TL431 or optocoupler failure | Temporarily disconnect optocoupler; if output jumps high, FB loop is the issue. | | No standby power, but fuse OK | Startup resistor (R2, 1MΩ) open or VCC capacitor (C13, 47µF 50V) dried out | Check R2 resistance; replace C13. | Before the current reaches the output headers, it
The is a textbook example of a flyback converter with primary-side PWM control and secondary-side TL431 regulation. Whether you are repairing a dead monitor or designing a custom 12V power source, understanding this schematic gives you a massive advantage.
Some key parameters of the a20112 power supply schematic include:
[ AC Input ] ---> [ EMI Filter & Protection ] ---> [ Bridge Rectifier ] ---> [ Interleaved PFC Stage (R2A20112) ] ---> [ DC Output Bus ] 1. EMI Filtering and Inrush Protection
