My air purifier does this weird flickering/resetting, at first you might rightfully assume it's a power supply issue, however as you can see in this video I've uploaded a demonstration of the problem where I'm injecting 5v to the board directly, also double-checking while powered from mains, the 5v supply looks solid and since there aren't many components, I've checked nearly all of them for shorts but nothing appears to be wrong with the support circuitry at least as far as I can tell, so my best guess at this point is the MCU firmware is corrupt, or it's partially dead, and it crashes as soon as it tries to boot, any other ideas what could be the cause of this? The name of the chip is sc91f844p but the datasheet is mostly in Chinese.
One noteworthy difference between mains vs injected power, is it turns on or hops between all the triacs for L/M/H rather than leaving just one open and after several seconds it seems to enter sleep mode, as the lights will turn off, it stops clicking with the buzzer and the fan spins on its lowest speed rather than sort of jumping between speeds.
One noteworthy difference between mains vs injected power, is it turns on or hops between all the triacs for L/M/H rather than leaving just one open and after several seconds it seems to enter sleep mode, as the lights will turn off, it stops clicking with the buzzer and the fan spins on its lowest speed rather than sort of jumping between speeds.
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