How to Check the Main Board of a TV

By Michael O. Smathers

A TV that doesn't come on or shows an odd picture or coloration has an electrical problem. In most cases, you might be tempted to box the TV up and send it to the manufacturer for repair or replacement. This can cost you hundreds of dollars especially if the warranty is expired -- not to mention the cost of shipping and handling. If you have a multimeter, you can diagnose problems on your TV's main, or circuit, board and buy the parts to replace faulty components.

Things You'll Need

  • Multimeter
  • Phillips screwdriver
  • Flathead screwdriver
  • TV board schematic diagram
  • Soft rug or towel

Step 1

Obtain a schematic diagram of your TV's circuit board from the manufacturer or online.

Step 2

Unplug the TV from the wall and place it face-down on the towel to avoid scratching the screen.

Step 3

Ground yourself to remove static charge by touching a metal object.

Step 4

Begin removing the back panel of the TV according to the diagram in your user manual. Keep both a Phillips screwdriver and flathead screwdriver; you may need both.

Step 5

Connect the multimeter's test leads to corresponding ports, usually color-coded. Red is always positive, or "Volt," and black is always negative, or "COM."

Step 6

Inspect the circuit board for outward signs of damage. Any warped, swollen or burned areas indicate a possible power surge.

Step 7

Set the multimeter to the appropriate measurement, such as resistance.

Step 8

Touch the leads to either side of a component. Compare the reading you get on the meter to the reading displayed on the schematic.

Step 9

Test each component on the circuit board in this manner until you find the source of the problem.

Step 10

Replace the component and reassemble your TV.

Tips & Warnings

  • Resistance is used to test resistors and diodes.
  • Keep away from the capacitors, labeled with a "C" on the circuit board and with two separated parallel lines on the schematic. They contain residual charge that can damage the multimeter or shock you. Similarly, stay away from power supplies.
  • Opening your TV will invalidate your warranty.