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Dark screen on Latitude E6410
The screen on our Latitude E6410 has gone very dark. Pressing Function + Up arrow repeatedly had no effect.
If I look very closely I can just barely see what is there, and I was able to log in. From there I right-clicked the desktop and chose Display Settings. On the Display Settings control panel, I can just see that the Brightness slider is all the way to the right.
BTW I was surprised to find that turning the room light off didn't help me see the screen better. With the room light on, I can just barely see what's on the screen. With the room light off, I see nothing at all.
Any suggestions?
UPDATE:
On further reflection, I think this probably narrows the problem down to the screen. Since I can (just barely) see and interact with it (log in, bring up the Display Settings control panel), I think that tells us that the motherboard and video card (if that's separate on this model) are fine. And the fact that I can only see the screen at all when there is light on it, and not at all when there is no light on it, suggests that the LED backlights are not working.
What do you think, am I correct? How likely is a new screen to solve the problem?
ejn63
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January 2nd, 2021 11:00
If you're sure the system has an LED backlit display, and the backlight is completely out, it strongly suggests it's the power to the backlight that's the issue. There is more than one LED in the backlight strip, and the chance of all of them going dark simultaneously and independently is low. More likely it's the power circuit to the backlight that's the issue, not the backlight itself. If you can find a schematic, you may be able to test the voltage input to the screen backlight to check. If not, it's likely wiser to replace the system board first -- not the display panel.
If the system has a CCFL backlight (it is old enough to have been sold at a time when these were still available), it may be that the inverter that powers the backlight (separate from the system board, unlike an LED backlight) is at fault.
ejn63
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January 2nd, 2021 11:00
On an LED backlit screen, the power to the backlight is integrated into the display wiring harness.
On a CCFL-backlit screen, the cable that supplies power to the backlight is usually separate from the rest of the wiring harness.
GregL65
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January 2nd, 2021 11:00
Thanks, but I'm surprised to hear that the cable that connects the screen to the motherboard would have separate power contacts for the display and for the backlighting. Is that the case?
BTW I tried using a flashlight on the screen, and that helps me see it much better, if only a small portion at a time, though it's still difficult to tell when a control panel menu item is selected. I do think the backlighting is completely off.
ejn63
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January 2nd, 2021 12:00
That means it's an LED backlight - but no, it doesn't pin down the fault. It's still either the power to the backlight (i.e., the system board) or the backlight itself.
If the failure was all of a sudden, it's more likely the mainboard than the backlight that's faulty, but neither part is very expensive to replace on this older system. If you must start with parts replacement, I'd replace the board first.
GregL65
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January 2nd, 2021 12:00
Yes, it was all of a sudden. My kids use this old laptop a lot, and it was working fine yesterday. Starting it up today one of them told me of this new problem.
GregL65
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January 2nd, 2021 12:00
It has a single connector, which is labeled, "NCLOO LED EDP CABLE". Would that isolate the problem to the screen?
GregL65
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January 2nd, 2021 12:00
More information:
It has a 30-pin connector. I wasn't able to find a pinout for that connector, but I did find this generic pinout for "Common Pin Out for eDP Panel Connector". It shows two pins for "LCD logic and driver power" (and two for ground), and four pins for "Backlight power" (and four for ground), below.
Would a motherboard problem be likely to make those four backlight power pins go dead all at the same time? Or would it be more likely that some kind of controller in the screen assembly for the backlights has gone bad?
U2CAMEB4ME
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January 3rd, 2021 03:00
Welcome to the Dell Community @GregL65
Unless you had disconnected the display while it was still powered on or did not drain residual power from the system board when doing so then it is most likely the display panel.
I have "Fried" a few LCD test beds doing this!!!
Have you removed the display to find the part number on the back of the panel???
Disconnect the AC, remove Main Battery and then hold down the power button for 10-15 seconds.
Peal off the display bezel, remove the four screws and place the LCD face down on the keyboard.
https://downloads.dell.com/manuals/all-products/esuprt_laptop/esuprt_latitude_laptop/latitude-e6410_service%20manual_en-us.pdf
Best regards,
U2
NOTE:
If you live in the US a may have a replacement that I could ship for free.