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Recently I've had an issue with my laptop (HP Pavilion 15-ab091na to be precise). I was using my laptop and suddenly the screen went black and a faint burning smell around the power button & power supply.

As the screen could still be seen when a light was shon on it. Furthermore, when the laptop was hooked up to an external monitor the picture was displayed fine.

I suspected the video cable from motherboard to the screen had frayed and potentially short circuited (causing the burning smell).

However, upon replacing the video cable I found the issue was not rectified and I am now unsure of what to do next/what has broken.

Any help/suggestions you could provide would be greatly appreciated!

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    If you can see the screen image when shining a light on it then it is probably the display backlight power cable or power regulators that have gone. – Mokubai Apr 4 '18 at 15:25
  • @Mokubai I see, are the power regulators part of the motherboard or are they part of the lcd? – Oli Apr 4 '18 at 15:33
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When an LCD display (laptop, notebook, or desktop) suddenly goes black, but one can still see a faint silvery image of text and graphics by shining a flashlight on the screen, that almost always means that the power-supply circuit for the back-lighting lamps has good bad.

The older type of back-lighting lamps were simple white fluorescent light tubes, similar to those you see lighting offices and some kitchens. These lamps are powered by a device known as an "inverter". This device is a long narrow circuit board, typically 15cm long by 1.5cm wide by 0.75cm tall. It usually resides in the upper (screen) half of your laptop, at the bottom, just above the hinge and the power button. A replacement inverter can typically be found for about $25, so it's not an expensive part. You can either buy one and replace it yourself (if you're good with tools, have steady hands, and can find a repair manual for your computer), or you can take it to a repair shop. I suggest the repair shop unless you have prior experience repairing portable computers; they have a lot of small parts which are easy to lose or break.

Newer LCD monitors, however, use arrays of LEDs to back-light the LCD screen. If this is the case with your monitor, the the power-supply circuit for the back-lighting LEDs has probably burned out. I'm not sure what kind of circuit that is, what it's called, or where it's located, but a look at the manual for your computer should reveal something called "LED Power Supply" or words to that effect; that's definitely the part I recommend replacing first. (Or having a technician look at, if you go that route).

In either case, the back-lighting power-supply circuit for a laptop or notebook computer is probably located in the lower part of the upper half, near the hinge and power button, which is why you smelled the burning smell at that location.

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  • Hey there, thank you very much for your reply! Initially I suspected it was the inverter also - but I read that they weren't in laptops with LED screens? There is a small bit of circuit board at the bottom of the LCD. Could it be looking like I'll be needing a new screen? Many thanks again – Oli Apr 5 '18 at 0:06
  • "Oli": A computer with a screen that suddenly goes dark (stops emitting light), but the text and graphics can still be seen by shining an external light on it, is NOT an LED screen; it's an LCD screen, using fluorescent light tubes (driven by an "inverter" board) to provide backlight. An LED screen is unlikely to go bad all-at-once, but if it did, you would NOT be able to read the text and graphics by shining a light on the screen, because there is no liquid crystal in a LED screen, just millions of little light-emitting diodes. And if they go dead, they emit no light and display no image. – Robbie Hatley Apr 5 '18 at 5:10
  • @RobbieHatley I think you are mixing up OLED screens with LED backlit screens. LED backlit screens use LEDs in place of the older CCFL tubes and give a more consistent backlight in less space and energy but would be powered in a similar fashion. OLED screens would be the ones with millions of individual LEDs per colour. Marketing idiots just decided to call LED backlit screens as LED monitors to confound and annoy. – Mokubai Apr 5 '18 at 6:50
  • @RobbieHatley Ah! Yes! I was getting in a bit of a muddle over my screens and that! Thank you! So, my laptop is listed as WLED. So, therefore the screen is backlit with LEDs but the actual screen is LCD, right? – Oli Apr 6 '18 at 17:35
  • "Oli" & "Mokubai": Ah, that explains it. Thanks for the clarification. In that case, I suspect that the power-supply circuit for the back-lighting LEDs burned out. I'm not sure what kind of circuit that is, what it's called, or where it's located, but a look at the manual for your computer should reveal something called "LED Power Supply" or words to that effect; that's definitely the part I recommend replacing first (or having a technician look at, if you go that route). – Robbie Hatley Apr 8 '18 at 1:27
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To update the situation and what I found; I took my laptop to a shop to get a diagnosis and it turned out it was an issue with the LCD itself, once it was replaced with a new screen it worked just fine.

Not entirely sure why or how the screen broke, but I do still have an odd screen flickering present so it might just be an issue with the design

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I had the same problem with an HP 15-ac173tu. I opened the laptop and found that the smell was coming from the burned fan motor which was not turning on to protect from extra damage. I removed the fan and everything is working fine.

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