A20112 Power Supply Schematic

Note: Since a raw image can’t be rendered here, the following ASCII-style logic flow defines the electrical connections:

AC Live --- Fuse --- EMI Choke --- Bridge Diode (+) --- Bulk Cap (+) --- Transformer Primary (Pin 1)
                                             |                        |
                                            GND                       MOSFET (Drain)
                                                                           |
                                                                      Source --- Current Sense Resistor --- GND Primary
                                                                           |
                                                                      PWM Controller (CS pin)

On the secondary side:

Transformer Secondary (Pin 7) --- Schottky Diode (Anode) --- Cathode --- Inductor --- 12V Output (+)
                                                                           |
                                                                      Capacitor Bank --- GND Secondary

The feedback path:

12V Out (+) --- Resistor Divider --- TL431 (Ref pin) --- TL431 (Cathode) --- Optocoupler LED --- GND
Optocoupler Transistor --- PWM Controller (FB pin) --- Adjust duty cycle.

The A20112 (specifically the R2A20112) is a high-performance Integrated Circuit (IC) developed by Renesas Electronics, designed as a Power Factor Correction (PFC) controller. It is commonly used in switching power supplies (SMPS) for high-power applications such as plasma TVs, large LED displays, and industrial power modules.

Understanding its schematic is essential for repairing or designing power systems that require high efficiency and low noise. Core Functions of the R2A20112 IC

The R2A20112 is a Critical Conduction Mode (CRM) interleaved PFC controller. Its primary role is to ensure the power supply draws current from the AC mains in a way that matches the voltage waveform, significantly improving energy efficiency and reducing harmonic distortion.

Interleaved Control: It manages two power stages in parallel but out of phase. This reduces the ripple current in the output capacitors and allows for smaller, more cost-effective inductors.

Efficiency: By operating in CRM, the IC minimizes switching losses, making it ideal for units like the HSP400-5S01 plasma power board.

Noise Reduction: The interleaved design inherently cancels out certain electromagnetic interference (EMI), leading to a "low noise" operation profile. Typical A20112 Power Supply Schematic Breakdown

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 EMI Filter 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

When dealing with a board using the A20112, failures often occur in the peripheral components rather than the IC itself. 12V Power Supply Repair

The Victoria 20112 is a revered boutique recreation of the classic Tweed Deluxe 5E3 circuit, known for its "creamy and warm" tone. For many amp technicians and DIY enthusiasts, looking at its power supply schematic is the first step in diagnosing issues like volume drops, sputtery sounds, or complete power failure. The Core of the 20112 Power Supply

The 20112 typically follows the traditional tube-rectified design, often utilizing a 5Y3GT or 5AR4/GZ34 rectifier tube to convert AC power from the transformer into the high-voltage DC (B+) needed for the vacuum tubes.

Rectification & Filtering: High voltage AC enters the rectifier tube and emerges as "pulsating" DC. This is smoothed out by high-voltage electrolytic capacitors (the "filter caps").

The "Dog House": In these vintage-style builds, these large capacitors are often housed in a metal cover under the chassis known as the "dog house".

Modifications: Some 20112 owners add a 1/2 power switch or an attenuator like a hotplate to make the amp more manageable for smaller gigs or home use. Common Troubleshooting Stories a20112 power supply schematic

When a 20112 stops working, techs often look for these common "characters" in the story of the circuit:

The workshop was silent except for the rhythmic tick-tick-tick of the wall clock, a stark contrast to the frantic energy usually surrounding Elias, the lead repair technician. On his anti-static mat sat a vintage 1980s industrial controller—the "

"—responsible for controlling a CNC machine that had just gone down.

The client was frantic, but Elias knew the drill. "It's always the power supply," he muttered, opening a thick, dusty binder of schematics. The Problem: A Dead Industrial Heart

The machine was showing a "Voltage Fault." Elias knew the A20112's power supply was designed to take high-voltage AC input and convert it into stable DC voltages (typically +5V for logic and $\pm$12V or $\pm$15V for operational amplifiers). Stage 1: Transformation: The input

goes through a step-down transformer to lower the voltage to a safer level.

Stage 2: Rectification: A bridge rectifier (often four 1N4001 diodes) turns the alternating AC signal into a pulsating DC signal. Stage 3: Filtering: Massive electrolytic capacitors ( ) smooth out the pulses into a nearly flat DC voltage. Stage 4: Regulation: Voltage regulators, like the popular Go to product viewer dialog for this item.

, lock the voltage at a precise, stable level regardless of load changes. The Investigation: Following the Schematic

Elias spread the A20112 power supply schematic out, tracing the path with a yellow highlighter. The input looked fine. He checked the bridge rectifier; no blown diodes.

He reached the Filtering stage. The schematic showed two large capacitors.

"Aha," he said, touching the top of one capacitor. It was slightly bulged—a classic sign of age-related failure. When capacitors fail, they cannot smooth the signal, leading to high "ripple," which causes voltage regulators to fail or produce unstable power, crashing the system.

Component Sourcing: Elias checked the schematic’s bill of materials (BOM), noting the capacitor rating: 35V35 cap V 105∘C105 raised to the composed with power cap C

Replacement: He desoldered the two old, tired electrolytic capacitors and soldered in new, high-quality replacements, ensuring the polarity was correct (minus to ground).

Testing: He powered up the unit, monitoring the output with his multimeter. A steady 12VDC12 cap V cap D cap C registered, and the rail was crisp. The Result

The machine hummed back to life, the erratic errors gone. By interpreting the A20112 power supply schematic, Elias hadn't just replaced a part; he had understood the story of the electricity flowing through it, saving the company days of downtime. If you are looking to repair or simulate this power supply, How to read the capacitor ratings ( 105∘C105 raised to the composed with power cap C 85∘C85 raised to the composed with power cap C Note: Since a raw image can’t be rendered

Where to find safe, modern replacements for 1980s-era components.

Make a Simple 12 Volt Power Supply : 6 Steps - Instructables

While "A20112" might sound like a secret government code, it’s actually a classic, compact LASCAR PSU20112 Go to product viewer dialog for this item.

linear power supply that has been a reliable "silent partner" in the electronics world for years. The Blueprint of a Workhorse The story of the

(PSU20112) is one of simplicity and ruggedness. Unlike modern "switching" power supplies that can be noisy and complex, this is a linear supply. Imagine a steady stream of water versus a fast-pulsing sprinkler; the

provides that smooth, steady stream of power that sensitive electronics crave.

The Mission: Its primary job is to take high-voltage wall power (110V or 230V AC) and "step it down" to a safe, steady 12V DC at 500mA.

The Armor: It is encapsulated, meaning the delicate internal components—like its transformer and regulator—are sealed in a protective block. This makes it a favorite for OEM use (built directly into other machines) where it needs to survive dusty or industrial environments. A Tale of Two Guards

The "heart" of the A20112's schematic isn't just about moving electricity; it's about protecting it. It features linear regulator ICs that act like watchful guards with two specific "superpowers":

Over-Current Protection: If a device tries to pull too much power, the guards "throttle" the flow to prevent a meltdown.

Over-Temperature Protection: If it gets too hot while working, the system automatically shuts down to cool off, ensuring it doesn't burn out the equipment it’s powering. Where it Lives Today You won't usually see an

sitting on a desk; instead, you’ll find it hidden inside the "brains" of other systems. It is the go-to choice for:

ITE (Information Technology Equipment) where low noise and high reliability are critical.

Precision OEM devices that need a "set it and forget it" power source that won't interfere with sensitive signals.

It’s not the flashiest part of a machine, but without its steady 12V output and "unbreakable" encapsulated design, many of the industrial systems we rely on simply wouldn't stay awake. Switching Power Supply Technical Manual - ADM and MEAN WELL On the secondary side: Transformer Secondary (Pin 7)

power supply schematic refers to the circuit diagram for the HP JC44-00250A

Low Voltage Power Supply (LVPS) board. This component is a critical power module used in several high-end HP LaserJet printers to provide stable voltage to the logic board and laser assembly. AliExpress Compatible Models a20112 / JC44-00250A board is compatible with the following HP LaserJet AliExpress Managed MFP Series : E72525, E72530, E72535 MFP Series : M72625, M72630 Color Managed Series : E77830, E77822, E77825, E77422 Key Specifications & Troubleshooting Part Numbers : Often listed as JC44-00250A JC44-00249A

: Restores power when a printer fails to turn on, shows error codes, or exhibits unstable performance. Service Manual

: Detailed pinouts and engine installation guides for these models can be found in the HP LaserJet MFP M72625/M72630 Engine Install Guide HP LaserJet E72525 Service Manual Common Failure

: Printers that press the power button but do not turn on often require a reset of this power module. AliExpress Procurement Options

If you are looking to purchase a replacement or find a specific technician-level schematic:

: You can find this board at specialized parts retailers like or on marketplaces such as AliExpress : Bulk orders are typically available through on this board with a multimeter?

This paper presents a comprehensive design, schematic, component selection, analysis, and implementation guide for the A20112 power supply. It covers functional requirements, block diagrams, detailed circuit schematics, component specifications, PCB layout considerations, thermal and EMI analysis, testing procedures, and a bill of materials (BOM). Assumptions: A20112 denotes a hypothetical single-output DC power supply delivering 12 V at up to 2 A (12 V/2 A) with both short-circuit protection and moderate line/load regulation; use-case is general-purpose bench or embedded-power application. Adjust ratings and safety standards to your exact A20112 specification if different.

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).

Step 1 – Visual Check: Look for bulging capacitors (C1, C8), cracked MOV1, blown fuse, or burnt Rsense.

Step 2 – Input Stage Check: Measure across C1. You should see ~300V DC (for 230V AC). If zero, check F1, MOV1, DB1.

Step 3 – Startup Voltage: 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.

Step 4 – Output Stage: Check D5 (Schottky) for shorts. Measure resistance across output terminals – if very low (<10 ohms), the output capacitor may be shorted.

Step 5 – Feedback Loop: Apply an external 12V (current-limited) to the output. Measure TL431 Ref pin – should be 2.5V. If not, check R12/R13. Then check optocoupler LED voltage (should be ~1.1V). If both are fine, the optocoupler transistor side on the primary may be open.

Step 6 – Replace Parts Systematically: Using the schematic, isolate sections. Never replace the MOSFET without checking Rsense and the PWM controller, as a bad controller will kill the new MOSFET instantly.