An autopsy of a higher profile LED lamp, courtesy of Matt. This is a very chunky module with an intriguing double-insulated construction that involves the driver being in a fully enclosed plastic housing including a cable port that protrudes through the alloy heatsink onto the PCB that is presumably a high thermal conductivity laminate as opposed to the more common aluminium core PCB’s.
This unit seems to use a series array of LEDs that each contain two chunky chips giving a combined forward voltage of about 6 to 7 volts on each of the 18 emitters. That gives a combined panel voltage of around 108V to 126V. Each emitter also seems to have a reverse silicon diode drop too, suggesting reverse polarity protection.
The panel was exhibiting an unusual failure mode of 10 of the 18 emitters being short circuit. This may have been due to the normal failure mode of gallium nitride emitters, or it may have been a deliberate open circuit shunt system to allow a high level of LED redundancy in the event of failure. That would allow the fixture to continue operating at reduced intensity as each emitter failed.
The thermal cracks on the emitter resin, silkscreen and cable suggested that the panel had been operating for a long time at a high temperature.
The driver is notable for the high level of input and output suppression to comply with EMC standards.
The strobing is common in modern drivers when they fail or the load is abnormal.
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