SDG #170 Troubleshooting the Ring Light PCB. JLCPCB Fail??

A freshly delivered batch of assembled LED ring light PCBs that refuses to light up is one of the more frustrating outcomes in hobby electronics, and this episode walks through the diagnostic process rather than jumping to conclusions. The board in question is the microscope ring light design from the earlier build video, ordered as a turnkey SMT assembly job, which makes fault finding a two part question: is the design at fault, or did something go wrong during manufacture?

The troubleshooting approach is the useful part here. Rather than reflowing parts at random, the process starts with basic continuity and voltage checks against the schematic, then narrows in on individual component footprints and the constant current driver circuitry to see where the expected voltages disappear. Comparing what the multimeter reads against what the design predicts is what separates a genuine assembly defect from a layout or footprint mistake made at the design stage, and that distinction matters if you plan to raise a complaint with a PCB house.

For anyone ordering their own assembled boards, the takeaways are practical. Component orientation and polarity markings on LEDs and small ICs are a common source of confusion between designer intent and assembler interpretation, and part substitutions or rotation errors can produce a board that looks perfect under the microscope while being electrically dead. Adding accessible test points and keeping the BOM unambiguous costs almost nothing at design time and saves hours of probing later. The episode ends with a fair verdict on where the responsibility actually lies, which is more informative than a simple pass or fail on the service itself.