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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