S36012 Power Supply Circuit Diagram -

Once stable, control of the power transistors is assumed by the ubiquitous (or its equivalent, the KA7500).

: Dual Pi-filters, consisting of safety X/Y capacitors and a dual-winding common-mode choke coil, prevent high-frequency switching noise from feeding back into your household mains grid. 2. Primary Rectification and Voltage Selection

PWM control IC to manage the switching frequency and duty cycle for precise voltage regulation. Secondary Stage:

+Vin (36V max) ----[Fuse]----[Reverse Polarity Diode]----+----[C_in+]----[C_in+]----+----[L1]----+----[C_out+]----[C_out+]---- Vout+ | | | | [Q1 Drain] | | | | +----[U1 Vin] | | | | | | [Q1 Source] | | | | +----[D1 Cathode]------[D1 Anode]---[GND] | +----[R_sense]----------------------[GND] | +----[RV1 wiper]----[U1 FB] | [GND]

Below is a development feature breakdown: a Technical Reference Design representing the "Circuit Diagram Feature" for an S36012-type 12V power supply unit. s36012 power supply circuit diagram

+--------------+ +--------------------+ +-------------------+ Mains | EMI Filter | --> | Bridge Rectifier & | --> | Half-Bridge | AC In | & Protection| | Voltage Doubler SW | | Switching Stage | +--------------+ +--------------------+ +-------------------+ | v +--------------+ +--------------------+ +-------------------+ DC Out | Output Noise | <-- | Schottky Rectifier | <-- | High-Frequency | Term. | & LC Filter | | & Smoothing Cap | | Transformer | +--------------+ +--------------------+ +-------------------+ | ^ | +------------------+ | +-------------> | PWM Controller & | --------------+ (Feedback) | Optocoupler Loop | +------------------+ 1. AC Input Protection and EMI Filtering

The S-360-12 employs a Switch-Mode Power Supply (SMPS) design, which is significantly more efficient and compact than traditional linear transformers.

Dual input, selectable via a manual switch between 110VAC and 220VAC (±15%).

Often utilizes a TL494 or similar Pulse Width Modulation (PWM) controller. Once stable, control of the power transistors is

High-power drop resistors draw a small current directly from the high-voltage DC bus to initialize the PWM chip.

: Most variants use the TL494 or a compatible PWM controller to manage the switching frequency and maintain a stable output voltage.

: The main primary switching transistors (13009) or the main input bridge rectifier have suffered a short circuit. Replace both transistors, inspect their accompanying base resistors, and test the rectifier block.

: A negative temperature coefficient (NTC) thermistor sits in series with the input line. When cold, its resistance is high, dampening large initial current spikes that could damage capacitors during startup. Primary Rectification and Voltage Selection PWM control IC

Have you found a different version of the S36012 schematic? Share your PCB photos and measurements in the comments below (on the original blog post).

: An adjustable reference zener diode checks the output line against a fixed internal value.

Arranged in a half-bridge topology, these components alternatively switch on and off at speeds ranging between 20 kHz and 50 kHz.

Understanding its internal circuit design is essential for troubleshooting, safely modifying, or repairing this workhorse power supply. Core Specifications Overview