The phototransistor inside the PC817 shifts its resistance on the primary side. This action changes the voltage on the feedback (FB) pin of the primary PWM chip, forcing it to adjust its duty cycle to correct the output. Common Failure Points and Troubleshooting
What is written on the main 8-pin or 6-pin control IC?
AC INPUT: Live → Fuse (5A/250V) → Switch → Transformer Primary AC INPUT: Neutral → NTC Thermistor (5D-11) → Transformer Primary
https://github.com/johnelectron/smps_schematics/blob/main/Wannien_101V0_revA.pdf
Electrolytic capacitors near heat sources are high-failure items. Verify they haven't "bulged" or dried out, especially those on the +12V rail. Common Repair & Troubleshooting Steps Safety First:
(up to 400V DC on the bulk cap and 1000V AC at the lamp connectors). Always discharge the large 400V capacitor before touching the board. If you are looking for a specific component ID
He rolled up his sleeves, pulled the dead MOSFET back out, replaced R17 with a fresh metal-film resistor from his drawer, and soldered in the new transistor. He probed the board against the schematic’s test points. Everything matched. 5V standby. 12V rail within tolerance. Feedback loop singing the right song.
Disclaimer: Ensure you are comfortable with electronics repair, and always disconnect power before working on the board. If you'd like, I can: Help you find a for your monitor. Suggest replacement components based on your findings. Compare this power supply to others you might be repairing. Let me know how you'd like to proceed with your repair . Share public link
If you found this verification useful, share the raw netlist with the open-source hardware community. A verified schematic is the difference between reviving a power supply and turning it into e-waste.
At 4:30 AM, he plugged in a spare hard drive as a dummy load.
The Wannien 101v0 is a switching-mode power supply (SMPS) commonly found in low-power consumer electronics, LED drivers, and industrial control modules. Due to the proliferation of uncertified clones and undocumented revisions, obtaining a reliable schematic for troubleshooting or repair is challenging. This essay outlines the systematic verification process applied to the Wannien 101v0 power supply schematic, confirming its topology, component values, and operational integrity.
