Toshiba 42HL67 Service Manual - Page 15

Does NO the screen light unevenly? (Normal screen with a shaded area) *** Warranty Concession required for LCD panel replacement. Digital photo may be requested. Contact Technical Support. NO Does the back light YES function and then turn off? YES This normally indicates a defective CCFL (Lamp). The display should be replaced. *** Is the back light YES NO supply source present shortly after the power switch is pressed? If it is available , try the CCFL inverter. If this does not help, replace the LCD display. *** (24V-Pins 1-5 CN804) Operation of the inverter can be determined by placing a Suspect the back light supply source. Is the back NO light switching signal (3VDC Pin 1- CN61) present shortly after the power switch is pressed? YES scope probe or frequency counter test lead NEAR the inverter. If the inverter is operating, the operating frequency (40 to 70 Khz) or waveform pictured below will be displayed. Do not connect the test leads directly to Suspect System the inverter! Control or Low-B supply problems. Using NO a scope or frequency YES counter, is the CCFL inverter operating? Suspect the CCFL inverter. 14