00:00Repairing a Samsung LED TV power supply board requires careful handling, basic electronics troubleshooting tools like a multimeter and soldering
00:07iron, and strict safety precautions.
00:10Safety-first, high-voltage capacitors on the power supply board can retain lethal electrical charges even after the TV is
00:16unplugged.
00:18Always unplug the TV, discharge the main filter capacitor, and work on a clean, insulated surface.
00:23For a clear visual overview of troubleshooting components and testing voltages, you can watch this helpful tutorial on YouTube, How
00:30to Repair Samsung LED TV Power Supply.
00:32Step 1, safety and disassembly.
00:35Unplug the TV, disconnect the power cord from the wall outlet, remove the back cover, lay the TV face down
00:40on a soft, flat surface.
00:42Boop, unscrew the outer casing and gently lift off the back panel.
00:45Locate the power supply board, this is usually the larger board where the AC power cord plugs in.
00:50Take reference photos of all wire harnesses and connectors before unplugging them.
00:55Discharge the main capacitor.
00:56Use a multimeter to check for residual high DC voltage across the large primary filter capacitor.
01:01Discharge it safely if necessary before touching any components.
01:05Step 2, visual inspection.
01:07Look for obvious signs of physical damage, bulging or leaking electrolytic capacitors, burn charred areas, a blown ceramic fuse, or
01:14broken solder joints.
01:15If the fuse is blackened, or open circuit, it usually indicates a downstream short, such as a shorted MOSFET or
01:22bridge rectifier.
01:24Step 3, check primary side components.
01:26Test the fuse, set your multimeter to continuity mode, and test the main fuse.
01:31If it beeps or shows zero resistance, it's good.
01:34If it's open, no continuity, replace it.
01:37But check for shorts first, or the new fuse will blow immediately.
01:40Test the bridge rectifier.
01:41Check the AC input pins to the DC output pins for direct shorts.
01:44Test the MOSFET.
01:46Measure across the drain and source pins of the power MOSFET.
01:49A zero resistance reading short circuit means the MOSFET is blown and needs to be replaced.
01:54Step 4, check secondary side and capacitors.
01:57Inspect and test capacitors.
01:59Look for domed or popped tops on electrolytic capacitors.
02:02Use an ESR equivalent series resistance meter to test them out of circuit if they look normal.
02:06But you suspect power and stability.
02:09Desolder and replace bad parts.
02:11If you find a shorted MOSFET, blown fuse, or bad capacitor, use a soldering iron and desoldering pump to clear
02:16the joints.
02:17Then solder in exact replacement components matching the voltage and amperage ratings.
02:21Step 5, test voltages.
02:23Plug in and power on carefully.
02:25Reconnect the board or test the voltages on the output pins leading to the main board.
02:28Verify standby output voltages.
02:31Check for stable standby voltage, typically 5V, and other output lines, 12V, 13V, or LED backlight voltages as marked on
02:38the board layout.
02:39If voltages fluctuate or are missing, check the PWM control IC input pin.
02:45And that's the full picture.
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