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4 Troubleshooting

4 Troubleshooting
4-1 Common Acknowledge
- If you change the interface board, be sure that the U105, U106 and U103 these three components also changed to the new I/F board because there was program inside. If not, please re-write EDID or upload firmware into Flash memory via VGA Cable. - If you adjust clock and phase, please do it at the condition of Windows shut down pattern. - If you confirm the R.G.B. color is normal or not, please do it under 16-grey scalar pattern. - This LCM is analog interface. So if the entire screen is an abnormal color that means the problem happen in the analog circuit part, if only some scale appears abnormal color that stand the problem happen in the digital circuit part. - If you check the H/V position, please use the crosshatch pattern. - This LCM support more than 30 timing modes, if the input timing mode is out of specification, the picture may appears abnormally. - If brightness uneven, repairs Inverter circuit or change a new panel. - If you find the vertical line or horizontal line lost on the screen, please change panel.

4-1

4 Troubleshooting

4-2 No Power & Power LED Off
No power

Check primary rectifier voltage

Check circuit if short

Check IC802, C805, T801

Check F801, P801, D801

Check pin3 of IC802 voltage about 1V

Check R801, R805, R822, R823, R817

Check pin2 of IC802 voltage about 2V

Check R803, R807, R824, R825

Check pin1 of IC802 voltage is 5.8V

Check R812, R816, C818

END

4-2

4 Troubleshooting

4-3 DC output voltage is unstable
Output Voltage Unstable

Check Vbe of Q801 below

Check circuit if short

Check ZD801, ZD802, ZD803, D803, D805

Check Q801, Q802

Check reference voltage

Check pins of IC801

Check R801, R805, R822, R823, R817

Check R810, R811

Check feedback circuit

Check Vpin3-4 of IC801 about 6V

Check C815, D806, R812

Check Vpin1-2 of IC801 about

Check C815, D806, R812

END

4-3

4 Troubleshooting

4-4 Output power is unstable
Unstable power

Check sampling Circuit

Check R810, R811, R818

Change R810, R811, R818 Check the R pin voltage of IC803 about 2.5V Check the C pin voltage of IC803 if 3V

Change IC803

Check R809, R808, R814, D809

Check pin1 of IC802 voltage is 5.8V

Check D806, C815 if short

Change D806, C815

Check pin3 of IC802 voltage about 1V

Change R801, R805, R822, R823, R817

END

4-4

4 Troubleshooting

4-5 Backlight can't be turned on
No backlight Yes No LED lamp is OK Yes

No power supply to inverter

Check the cable that from I/F BD to P/I BD is ok

Yes Is there 14V voltage on pin 3,4 of T501, T502 Yes Is there PWM signal on pin 4 of IC501 Yes Is there High level voltage on pin4 of IC501 Yes No Lamp connector opened No Check I/F BD No Check I/F BD No U501, U502 fail No Check power supply

Replace U501, U502

Vsense voltage 2.9V No Are there PWM signal on pin1, pin15 of IC501 Yes Pin 5 of IC501 voltage is Low level Yes Pin 5 of IC501 voltage is high level voltage

No IC501 failure

Yes Feedback circuit failure

Yes

Check R523, D504, R529, D507, R528, R533

Yes IC501 protected

Yes

Check D505, D506, D510, R522, R521, C520

END

4-5

4 Troubleshooting

4-6 Black Screen and backlight turn on
Black Screen

Check power supply: Pin1, 2 of CN101 Yes Check pin34, 51, 66, and 82 Of U105 Yes Check pin32, 49, 56, and 75 Of U105 Yes

No Power Fail

No Check FB103 And U102

No Check FB106 And U101

Check Reset (pin84) Of U105 Yes Check Crystal: Pin96, Pin97 Of U105 Yes Check CCFLEnable (pin85) of U105 No MCU Fail Yes

No Check C144, R172

No

Check: X101, C153, C154

Check pin5 of CN101 No

Yes Inverter Fail

Check R167, Q106, R108, R110

4-6

4 Troubleshooting

4-7 White Screen
White Screen

LVDS Cable Reinsert No

Yes Workmanship

Change LVDS Cable No Yes

Yes LVDS Cable NG

Check VLCD Is 5V? No Check Panel Enable Of U105 (pin48) is High?

Check LVDS Signals No Check the HW Reset Of U105 pin84 No Yes

Yes Panel Fail

No Check C144 R172

Check R168, R105, Q103, Q101 Check the pins Of U105

END

4-7

4 Troubleshooting

4-8 Bad Screen
Bad Screen

LVDS Cable Reinsert No

Yes Workmanship

Change LVDS Cable No Check Crystal:Pin96,97 Of U105 Yes Check the communication Of U105 and U106 Yes Check the pins of U105 and U106

Yes LVDS Cable NG

Yes

Check :X101, C153, C154

No

Check: SDO, SCZ, SCK, SDI, Reset

4-8