TV Power Supply Board Guide: Symptoms, Testing Basics, Part Numbers and Safe Replacement

The power supply board is the heart of a TV's electrical system. It converts household AC power into the lower DC voltages the main board, T-con and backlight need. When it fails, the TV may not turn on, may click repeatedly or may start and shut off. Replacing a power supply board with the matching part is one of the most common TV repairs. This guide explains the symptoms, safe basic checks, how to find the right board and how to replace it.

What the power supply board does

The board takes in 120-volt AC from the wall and produces several DC outputs, typically a standby voltage that keeps the TV ready to respond to the remote and main voltages for the main board, audio and backlight. Many LED TVs combine the power supply with the LED driver, and some smaller TVs combine power and main board functions on one board.

Common symptoms of power supply failure

• Completely dead: no standby light, no response to the remote or buttons.
• Clicking: a relay clicks repeatedly as the TV tries and fails to start.
• Power cycling: the TV turns on, then off, in a loop.
• Delayed start: the TV takes longer and longer to turn on, often a sign of aging capacitors.
• Blinking standby light: many TVs blink a fault code; check the service manual.
• Sound but no picture: on combined power/LED boards, this can indicate a backlight driver fault.

Safe first checks

1. Test the outlet with another device and try a different power cord if the cord is detachable.
2. Unplug the TV for a few minutes, then plug it back in to reset it.
3. Disconnect external devices and HDMI cables to rule out a short or CEC issue.
4. Note the standby light behavior and any blink pattern.

Beyond these steps, diagnosis involves opening the TV. Signs like bulging or leaking capacitors or burned components point to the power supply, but internal testing should be done by someone experienced with electronics safety.

How to find the right board

1. Write down the TV model number and version from the label on the back.
2. Unplug the TV, remove the back cover and locate the power board, usually near where the power cord enters.
3. Read the part number on the board's sticker or printed on the circuit board. Examples include BN44 numbers for Samsung, EAY or EAX numbers for LG and long alphanumeric codes for Philips and Emerson boards.
4. Match the full number exactly. Our listings show the brand part number and, where available, the board's printed number and compatible TV models.

If your TV uses a combined main/power board, also see our guide on how to find a TV main board or T-con part number.

Safety first

Power supply boards contain large filter capacitors that can store a dangerous charge for some time after the TV is unplugged. Always unplug the TV, wait several minutes, avoid touching the board's components and handle it by the edges. Never operate the TV with the back cover off unless you know how to work safely around live circuits. If you are not experienced, have a qualified TV technician do the repair.

Replacing the board

1. Unplug the TV and lay it face down on a soft surface.
2. Remove the back cover screws and the cover.
3. Photograph the board and its connectors.
4. Disconnect the cables, including the AC input, then remove the mounting screws.
5. Install the new board, reconnect every cable and replace the screws.
6. Reattach the cover and test the TV.

Repair or replace the TV?

A power supply board is often one of the less expensive TV repairs, which makes it worthwhile for larger or newer TVs. If the panel is cracked, several boards have failed or the TV is small and inexpensive, a new TV may make more sense.

Common mistakes to avoid

• Ordering by TV model alone without checking the board's part number.
• Replacing the power supply when the real problem is the main board or LED strips.
• Touching board components before capacitors discharge.
• Forgetting to reconnect a cable, which can look like a failed board.

Each board is listed by its brand and part number. Match the number printed on your board and, where shown, the TV model and version.