Primary conversion
Secondary/regulation
Supervisory and sequencing
Protection and filtering on outputs
The TL494’s output signal is too weak to drive the main transformer directly. The 101V0 uses an intermediate driver transistor (often a TIP122 Darlington) to boost the current. wannien 101v0 power supply schematic verified
Verified Failure Mode: If the 2N3055 fails shorted (collector to emitter), you will get full unregulated voltage at the output terminals regardless of the potentiometer setting. This is dangerous for connected devices. Immediately replace the 2N3055 with a genuine TIP35C or MJ15003 for better reliability.
The transformer (labeled T101) had ambiguous pin markings on the draft. Using an LCR meter and ring tester, the primary inductance (1.2 mH), leakage inductance (32 µH), and turns ratio (primary:aux:secondary = 10:3:1) were measured. The verified pinout was added as a correction note. Primary conversion
| Symptom | Likely failure (from schematic) | Test point | |-----------------------------|-----------------------------------------------------|------------------------------------| | No output, fuse intact | Startup resistor open, or IC1 dead | Voltage at IC1 pin 7 (should rise) | | Output voltage jumps / unstable | TL431 divider resistors drifted, optocoupler weak | Output divider junction (~2.5V) | | Output low (e.g., 8V instead of 12V) | Secondary filter capacitor high ESR, or feedback loop broken | Check C2, C3 with ESR meter | | Squealing noise + no output | Transformer shorted turns, or output short circuit | Resistance across secondary winding | | Blows fuse immediately | Bridge rectifier shorted, MOSFET shorted D‑S, bulk capacitor shorted | Diode test on D1–D4, MOSFET |
Having the verified schematic allows you to trace the exact signal path and measure voltages against expected values. Secondary/regulation
This article explains the Wannien 101V0 power supply schematic, summarizes its key stages, verification checks, common problems and fixes, and safe testing practices. Assumes a basic understanding of electronics (AC mains, transformerless/transformer supplies, regulators, diodes, capacitors).