Boris_yo
2 Iron

DELL Latitude E6420 Does No Longer Show Display

I always put my laptop on standby and turn it off only when required. Today 4 hours after I left it on standby, I could wake him up from standby but could not see anything on screen which worked and all operating system sounds could be heard, hard drive worked as well. I tried powering it off and on, entering BIOS but I still could not see display. Here's a link to YouTube video that portrays what I see:

I later saw information here on how to access ePSA testing environment so I followed the steps: removed battery, plugged off power supply, pressed Power Button for 1 minute to drain power, held Fn key and powered laptop on until I heard funny sounds. This was ePSA probably but I still could not see anything on screen:

If I am not mistaken, my laptop was running on dedicated nVidia graphics card. What should I do now? Luckily I have customer on-site warranty still valid, but I am looking for a faster way to solve problem. Who knows, but it may be a mere problem of cable got lose which is in my abilities to fix. Thanks.

0 Kudos
14 Replies

RE: DELL Latitude E6420 Does No Longer Show Display

Hi Boris_yo,

I would suggest you to connect an external monitor with the system and check if you are able to get proper display on external monitor.

Here are the steps:

  • Shut down the system.
  • Connect the external monitor with the Blue VGA connector (VGA cable/connector is the normal cable that connects the monitor to the desktop system).
  • Restart the system and power on the external monitor, press the Fn key and hold it down and while holding it down, press the F8 key this would switch the display to the external monitor.
  • Check if you are getting the display on the external monitor.

Please share if you have received any error codes or beep codes when you power on the computer.

Please run the LCD built in self-test. Here are the steps:

  • To run the LCD BIST (Built in Self-test) Press and hold the D key on the keyboard while pressing the power button, then release both at the same time.
  • This will initiate a grey screen, then Red, then Blue, then Green then White, to allow you to inspect the entire LCD for color purity on each screen and to better identify defect such as cracks in the LCD or stuck pixels that may not be apparent in a normal viewing mode.

Please share the findings.

Awaiting your response.

Thanks & Regards

Garima G
#iworkfordell
To know more about Dell Product Support, Drivers & Downloads, Order & Dispatch status -> choose your region USAIndia. For helpful Dell Support Videos, you may click Here.
0 Kudos
Boris_yo
2 Iron

RE: DELL Latitude E6420 Does No Longer Show Display

DELL-GARIMA thanks, the test worked and I could see colors you mentioned. I do not have necessary equipment to test on external monitor though.

0 Kudos

RE: DELL Latitude E6420 Does No Longer Show Display

Hi Boris_yo,

Since the test passed it means that the LCD is fine. I would suggest you to re seat the LCD cable.

You may refer to the link http://bit.ly/188KCSV to check the manual on how to re seat the LCD cable. Select the display option from the content table.

Note: Please follow the safety instructions mentioned on the manual.

Awaiting your response.

Thanks & Regards

Garima G
#iworkfordell
To know more about Dell Product Support, Drivers & Downloads, Order & Dispatch status -> choose your region USAIndia. For helpful Dell Support Videos, you may click Here.
0 Kudos
Boris_yo
2 Iron

RE: DELL Latitude E6420 Does No Longer Show Display

 Hello DELL-GARIMA. What I did was the following:

1. Reseating 2 of LCD connectors - LCD screen works (as we determined previously), still no display

2. Removing one of 2 memory modules and placing first into slot of another

3. Disabling in BIOS internet NIC, wireless NIC, eSATA, USB ports, Serial ports, Intel Hyper Threading, Intel Visualisation etc.

4. Resetting CMOS

Only resetting CMOS helped but it was shortlived because after saving changes in BIOS and restarting laptop again, I once again could not see anything displayed. Once again I resetted CMOS and monitor was displaying until at the BIOS post screen I was offfered to press F2 for starting testing environment. I hit F2 and was brought into testing environment but nothing was displayed. Again for the 3rd time I resetted CMOS and somehow managed to enter testing environment by holding Fn and Power keys. Testing environment did not detect problems with video card but it showed error with LCD screen, picture of which you can find with link to my Dropbox album folder where you can see additional information. I Googled this error and it was said that newer BIOS versions have problems with previously manufactured laptops thus it does not detect LCD wire so consider this false positive and not hardware according to what this thread says.

I ran video card test in testing environment and recorded what I saw which you can check by going to my Dropbox account and you will find link below. I don't know if this is what video test supposed to be but it seems weird since expected something that makes sense. Here I see distorted line going from top to bottom and disappears after which nothing else happens until I hit Esc. But here is where it gets interesting: previously I could set which video card to use in BIOS. It was feature called nVidia Optimus but now, I no longer see that option or any related option where I can set my video card. Strangely, first time booting to BIOS works after resetting CMOS and in system information I see "Intel HD Graphics", its version and memory size. Of course should I save changes and restart laptop, I can no longer see anything on screen again. Is this problem with my dedicated video card? (nVidia NVS 4200M) Which brings me to question: why Dell laptops with primary and dedicated video card cannot fallback to default primary video card or video card that works? If I have dedicated and primary video card, what use will primary card make if it is not usable in scenario dedicated video card fails?

Please take a look at the picture of 2 LCD screen connectors here. I want to know what does first connector and what does second. Maybe I could plug out connector that is connected to dedicated video card and leave one connected to primary video card? Even if Dell implemented "fallback to default working video card" feature, what if my case is complex as failing video card is detected as working thus BIOS switches back to it everytime?

Here is a link to my Dropbox account which has troubleshooting shots I took and also video clip of me testing video card in testing environment. If you cannot access resources outside your workplace then let me know, I will think of something.

Thanks for helping me.

0 Kudos

RE: DELL Latitude E6420 Does No Longer Show Display

Hi Boris_yo,

Thank you for sharing the information. I appreciate your technical expertise.

I would request you to ignore the error which says LCD cable error, this error comes due to a limitation in BIOS. Once the system will boot to normal mode, we will update the BIOS and the error message should be rectified.

Also, I would suggest you to replace the CMOS battery and check for functionality.

Try working in the safe mode. Refer to this link on how to access safe mode:

Once you log on to safe mode, please remove the graphic card drivers and reboot the system. Here are the steps:

  •  Press ‘Windows’ key + R on ‘Desktop’ screen 
  •  Type ‘devmgmt.msc’ in run box and press ‘Enter’
  •  Click > or + sign next to ‘Graphics Adapter’ in Device Manager to expand the options.
  •  Right click on the graphics card entry and click ‘delete’.
  • Restart the computer and check for functionality.

If you are able to boot in normal mode, please reinstall the drivers once again and check for functionality.

Please revert back with the findings.

Awaiting your response 

Thanks & Regards

Garima G
#iworkfordell
To know more about Dell Product Support, Drivers & Downloads, Order & Dispatch status -> choose your region USAIndia. For helpful Dell Support Videos, you may click Here.
0 Kudos
Boris_yo
2 Iron

RE: DELL Latitude E6420 Does No Longer Show Display

I don't think the CMOS battery is to blame because it either powers BIOS chip to keep information or it doesn't. In my case it does and there is nothing wrong with it. Let me remind you again that I cannot continue further BIOS message after computer's POST. There's nothing on display so I can do nothing until I pull out CMOS battery again and my computer POSTS so this cycle continues. I can't even access internal BIOS hardware testing environment because displays shows nothing so we can forget about everything that comes past POST screen.

0 Kudos
dgoforit
1 Copper

RE: DELL Latitude E6420 Does No Longer Show Display

First fully boot up system, when it's fully loaded, then. press/hold these 3 keys "ctrl" "alt" and "delete" all at same time for 2 seconds.

Then let go all keys, then press the down arrow key two (2) times ... the key arrow pointing down is in the right lower corner. of the keyboard,  Then press enter.

At that point you will or should see the display turn on.

Give it a try.

So is the screen totally blacked out, or can you see some  light behind the dark screen? If you can still see light behind the dark screen, it's the display inverter board., 

Also connect a external screen to the VGA output of the laptop, if you can't find a vga cable,  If your taptop
has an HDMI port, connect it to a tv with a HDMI port.

0 Kudos
dgoforit
1 Copper

RE: DELL Latitude E6420 Does No Longer Show Display

boot up system/laptop, when it's fully loaded, then pres the CTRL ALT DELETE keys, hold them down at the same time for 2 seconds.and let go.

Then, find the ARROW key pointig down (it's in the right lower corner of the keyboard, then press DOWN ARROW key 2 times, then press enter.

At this point the display will show up.

0 Kudos
radef
1 Copper

RE: DELL Latitude E6420 Does No Longer Show Display

Hello,

My E6420 just tonight started showing the same issue.  The backlight on the LCD works (I can see it) but the display is not displaying any text or graphics.

Did you ever get this resolved?  What did you do?

I can share that an external monitor works OK for me.  

0 Kudos