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Title:Shonky CCTV power supply teardown
Duration:17:30
Viewed:86,759
Published:22-02-2024
Source:Youtube

This is a generic imported CCTV power supply bought from eBay. There are a few issues with it, mainly the quality of manufacture, electrical isolation and wire colour choices. The large holes to allow a wide tolerance of the mounting pillars may shunt the positive rail to ground if too far off centre. If that happened and a circuit had the negative referenced to ground elsewhere it could result in quite a high current flow without any inline protection. Some insulating washers on the case mountings would avoid that. The poor electrical clearance was completely avoidable. The Chinese manufacturers don't seem to be too fussed about separation between high and low voltage. Swapping the live and neutral would reduce that hazard, but that's a bodge fix. The spare PTCs were puzzling until I saw how splayed the legs of the PCB mounted ones were. These components cycle thermally in use, so that may result in stress on the lead connections. The switchmode power supply is a joy of complexity, with its low voltage controller chip controlling circuitry that has strong self-oscillating ballast type vibes. It almost looks like the unit starts self-oscillating to power the output and control circuitry, and then gets its feedback transformer magnetically shunted or controlled by the low voltage side. I'd like to see a schematic for this unit. Reverse engineering it would be made tricky by the two custom wound multi-winding transformers. It's an interesting unit, but not one I'd trust for a safety critical application. Incidentally, the first cable I tested it with turned out to have a three pin plug and socket, but just two core flex connecting them. It was supplied with a studio light from eBay. If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:- https://www.bigclive.com/coffee.htm This also keeps the channel independent of YouTube's algorithm quirks, allowing it to be a bit more dangerous and naughty. #ElectronicsCreators



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