DCDG
1 Copper

RE: DELL Latitude E6420 Does No Longer Show Display

Sounds like you have a Bad Display or a Bad Display Cable/Ribbon/Connection.  It's not the Video Card since you can view on a a External Monitor.  The Display Cable/Ribbon is the Cheaper of the two so I'd try and Replace that first(or at the very least check and make sure the cable/ribbon connection is seated properly on both sides display side/motherboard side).  If you have the ribbon check to see if there's crack on it. if there is...good possibility it's the problem

If you look into the screen and see no backlight but can see text/graphics then we know it's still getting data and that's when we know it's not a data cable and possibly the inverter board/light but if all you can see is the light and no image whatsoever.  It's either the display/data cable/ribbon or the display itself.

If you  can't view through a external display, then it's the video card which is typically integrated onto motherboard.


1. Seat cable/ribbon properly and check if a crack on the ribbon(no money needed for this step).

2. Replace Cable/Ribbon(inexpensive compared to replacing screen).

3. Replace Display

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Boris_yo
2 Iron

RE: DELL Latitude E6420 Does No Longer Show Display

Yes I did and in my case it was malfunctioned onboard nVidia graphics chip because no external means worked for trying to output signal. I could have chip extracted from motherboard and replaced with new one which I could order from eBay, I could pay DELL authorized service center over $800 to have motherboard replaced due to expired warranty but only paid them $60 for basic checkup which led to quote of over $800 from them. I could easily buy same new model from eBay so what I did was ordered motherboard on eBay for $130 and personally replaced old with new motherboard thus saving $670 and enjoying the experience along the way.

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radef
1 Copper

RE: DELL Latitude E6420 Does No Longer Show Display

Sounds like my problem might have been a little different.  Here's some details on my symptoms and how I got it working again.

Symptoms

  • LCD backlight was on
  • No text or graphics displayed 
  • No BIOS screen
  • External monitor worked OK
  • Pressing D on powerup caused the internal LCD panel to flash black, white, red, green, blue, etc

Troubleshooting:

  • I had a E6430 at my disposal as well - so I used it to see what was working or not on the E6420
  • At first, I removed the bottom panels from each laptop and routed the E6430 display cable to the E6420 motherboard.  I powered on E6420 and the display (now on the E6430) worked OK. 
  • Likewise, I took the E6420 display cable and attached to the E6430.  When I powered on the E6430 the display (now on the E6420) did not work.
  • This all lead me to believe the problem was in the LCD assembly on the E6420 since the problem followed the panel.
  • I was going to swap inverters, but the inverter assemblies are different between the two computers.  
  • Next, I swapped the LCD panel itself.
  • When I put the E6430 panel into the E6420 - it worked.
  • When I put the E6420 panel into the E6430 - it worked.
  • So both LCD panels themselves work...  I figured the problem is probably in the cable between the LCD and the motherboard.
  • However - when I reassembled everything - the E6420 was now working.

Resolution

  • While not 100% confident, I suspect there was a bad connection on the back of the LCD panel of the E6420.  When I removed the cable (for troubleshooting) and re-attached it, the laptop and display began operating normally.

Hope this helps someone else down the road!

For reference, here's the E6420 service manual which aides in disassembly:  

ftp.dell.com/.../latitude-e6420_owner%27s%20manual_en-us.pdf

Etabeta2017
1 Copper

RE: DELL Latitude E6420 Does No Longer Show Display

Thanks radef, I have the same problem I disconnected lcd but did not understand what cable you are referring to.

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Etabeta2017
1 Copper

RE: DELL Latitude E6420 Does No Longer Show Display

up

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