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Old 11-28-2021, 01:37 PM   #1
Badcaps Veteran
Join Date: Dec 2010
City & State: Alberta
My Country: Canada
Posts: 3,051
Default S-10-5 power supply schematic etc. 5V 2A

I got a 5V 2A power supply for some hobby projects from Aliexpress store YXD Wish for about $4. S-10-5 and the build quality good, solder blob under transformer and a solder balls on the PCB top so I cleaned that up.

Powered it up, get 5.0V but when connecting a load resistor it cratered. At 10R load which should be 0.5A, it dropped to 3.8V out and it went into hiccup mode below 5 ohms. About 1.5W output is all I can get.
I drew out the schematic and poked around with a scope. It's running slow at 31kHz and primary current pulses are measly 30mA. So I think the IC is fake and not working, it has no markings.
It appears to be a TX203H alternates are CR6203, RM6203, SDC603, SW2604, SL2128B. Commonly used in wall warts.
(The bottom rung version of this same S-10-5 using phenolic PCB, uses IC DK1203 Dongke Semi and no current-sense resistor, and cheapened other stuff.)

I asked for a refund and so far the vendor is quiet... I had another one ordered from a different Ali store but the floods took out rail and highways to the coast so it will be a while to get here and compare.

Don't forget website comparing pinouts of SMPS IC's. Good tool to reverse-engineer the IC used when there are no markings or it popped.
Attached Images
File Type: jpg S-10-5 power supply333.jpg (98.6 KB, 20 views)
File Type: jpg S-10-5 power supply top731.jpg (206.3 KB, 24 views)
File Type: jpg S-10-5 power supply bottom with solder blob 935.jpg (260.2 KB, 18 views)
File Type: jpg S-10-5 power supply 5V 2A schematic badcaps.JPG (152.9 KB, 26 views)
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