Chapter 6- Trouble Shooting; Common Acknowledge; N O Power Led Off - Dell 1909Wf Service Manual

Service Manual

Chapter 6- TROUBLE SHOOTING

Common Acknowledge

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If you change the M/B, be sure that the U101,U102 and U105 these three
components also changed to the new M/B because there was program inside.
If not, please re-write EDID or upload firmware into serial flash(U105) via
VGA Cable. How to do please refer to the Page 19.
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If you adjust clock and phase, please do it at condition of Windows shut
down pattern.
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Please confirm the R/G/B color under 32gray scale pattern.
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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.
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If you check the H/V position, please use the crosshatch pattern.
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This LCM support 10 timing modes, if the input timing mode is out of
specification, "Cannot Display this Video Mode" will be displayed on the
screen.
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If brightness uneven, repairs Inverter circuit or change a new panel.
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If you find the vertical line or horizontal line lost on the screen, please
change panel.
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If the self-test pattern is moving on the screen, please check whether VGA
Cable is plugged in the Monitor or PC if select analog model on OSD or
check whether DVI Cable is plugged in the Monitor or PC if select DVI
model on OSD . If the VGA or DVI Cable is plugged in well, please change
another VGA or DVI cable.
No Power and LED Off
Is the voltage at C854 in the
Is the voltage at pin8 of U850 354V?
Is the voltage at pin5 of U850 18.2V?
Is the voltage at pin3 of T850 about 518V?
Is there DC16V at L852
Is there DC5V at L851
NO
range of 127V~339V?
YES
YES
YES
34
NO
Check RT850, F850
NO
Check R853
NO
Check D852