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@@DAKElectronicsLab please just do more SMPS repair videos.

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Thank you

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Without those boring theories, you'd never be able to fix some SMPS units that I've repaired. Such as the primary filter cap failing, dragging the primary drive out of spec, killing some probably dodgy secondary filter caps to their demise and shorting a feedback zener and that, killing the feedback optocoupler. Once, where the zener entirely failed to faithfully short, but broke down under voltage and only detectable easily with a curve tracer. That last, generating some profanity, as my curve tracer wasn't immediately available... The boring theory part, due to the main filter on the primary gaining increasing ESR, ripple increased, causing output currents to climb, which subsequently lead to zener failure and supply runaway. Would also see in some supplies the secondary capacitors turned into popcorn, went straight into the feedback circuit, found the faults and fixed them, then went back to see if primary cap, driver or any additional secondary caps had been damaged.

Thank you 😊

The driver chip shorted, overcurrenting the fuse to failure. The capacitor being the most probable initial cause to to spikes caused by increased ripple, secondary to increasing ESR in the capacitor, lowering its efficiency and eventually, capacitive value. The ESR of the capacitor will tell the tale earliest, before complete failure or the value drifting substantially, as most cases of elevated ESR originate from the crimps that are behind the rubber seals in the electrolytic capacitor's base allowing the crimp connectors to oxidize, while electrolyte slowly evaporates, increasing the resistance in series with the capacitor.