Inside: a landscape of scorched copper traces, four swollen electrolytic capacitors (their tops bulging like tiny volcanoes), a cracked TO-220 transistor (label: ), and a resistor so blackened it looked like a piece of charcoal. A puzzle with missing pieces.
She rebuilt the schematic herself on a torn piece of cardboard: transformer → bridge rectifier → filter caps → 2N3055 pass transistor → LM723 control IC (she’d found one hiding under a heatsink) → feedback divider. A clumsy drawing, but hers . Wannien 101v0 Power Supply Schematic
On the seventh night, she plugged the repaired 101v0 into her father’s radio. The dial lit amber. Static hissed. Then, faintly, a voice in Cantonese reading shipping forecasts. Inside: a landscape of scorched copper traces, four
She’d searched. Oh, how she’d searched. The model was obscure—a short-lived Taiwanese clone of a Japanese linear supply from the late ‘80s. Wannien Electric Co. had gone bankrupt in 1994. No PDFs. No forum archives. No grainy scan on a Russian electronics site. Just dead links and a single Reddit post: “Anyone got the 101v0 diagram? Mine went pop. Help?” No replies. A clumsy drawing, but hers
Linh didn’t know what an optocoupler was. She learned that night on a borrowed phone with a cracked screen, flashlight app illuminating her father’s handwritten notes in the margins of a 1987 electronics textbook. He had drawn a small circuit—half a schematic—in blue ink. The title: “Wannien 101v0 — output stage repair, 2003.”
She took a photo of her cardboard schematic and posted it in that old Reddit thread. Subject line: