# Dell Inspiron 1750 - Black Screen



## gwgmer (Sep 27, 2011)

This is an interesting problem that I think I've got figured out, but I'd like to know if anybody else comes to a different conclusion.

A client of mine dropped his Inspiron 1750 and cracked the LCD. He decided to try to do an LCD replacement himself, ordered a compatible screen and was able to successfully install it. He said that upon boot with his new screen, it didn't show any video during POST and Windows boot, but did show the login screen. He logged in, worked a while, then restarted the computer.
After he restarted it, he turned it on to find the screen black. He said he swapped the new screen for the old one as a test and saw the same blackness - while the old screen was cracked, he still saw colors on it.

It's at this point he called me. I confirmed that the new screen was fully black - and let me elaborate on what kind of "black" I mean. You can clearly see the screen "light up" when you turn it on, from the dull black of a laptop that's off to a sharp, deep black that indicates that the backlight IS receiving power, but the LCD isn't displaying anything. And yes, I did shine a light onto the LCD just to see if I could see anything on the screen - I could not.
If I hook up the laptop to an external monitor, it displays onto that just fine. Everything works perfectly. Ergo it's not a system problem.

I've tried swapping out both the LCD and the cable connecting the LCD to the board. No luck - I get the same behavior either way. It's as if the LCD simply isn't receiving a video signal. I'd find it very odd if the external monitor display was working and the LCD wasn't, but it's the only possibility I can think of. Perhaps the jack on the motherboard is damaged - that's my only guess.

I have tried booting the computer without the HDD or RAM, but I don't get any video there either. Again, I know it isn't a system problem since everything works fine on an external monitor. At this point I'm fairly sure at that the motherboard is at fault...I suppose I just want to know if you all concur with my assessment, or if there's something else that I don't know about that might be the cause here.

Thanks much for any help!


----------



## joeten (Dec 4, 2008)

Hi and welcome to TSF could be the controller was damaged but lets see if anyone else comes up with anything


----------



## gwgmer (Sep 27, 2011)

Does anyone have any other comments on this issue? I really would appreciate any input someone could give me.

Additionally, let me clarify something which I felt was unclear in the initial post:
When I said: 
"After he restarted it, he turned it on to find the screen black. He said he swapped the new screen for the old one as a test and saw the same blackness - while the old screen was cracked, he still saw colors on it."

In the last sentence, I meant that before he replaced the old screen initially, it was cracked but still displaying some video. After he swapped in the new screen and it went black, he swapped the old screen back in, and instead of showing the colors that you normally see on a cracked screen, it now showed black like the new screen.

Thanks!


----------



## joeten (Dec 4, 2008)

Did he recheck the connections on the cable from the screen to the motherboard


----------



## gwgmer (Sep 27, 2011)

Yes, the connection has been checked and rechecked.


----------



## joeten (Dec 4, 2008)

Hi check for a board fault possibly the controller


----------



## SA Spurs1 (May 2, 2009)

Well you have not replaced the inverter.


----------



## joeten (Dec 4, 2008)

Dang forgot that thanks SA Spurs1


----------



## patrulheiro (Dec 11, 2008)

Hey all, I know this is an old thread but I came across the same issue and just wondering if anyone managed to get this resolved properly. Dell Inspiron 1750, screen black. The backlight is working but no display. If I plug in a external monitor it works fine. Exactly the same situation and for what I heard around it seems that this LCD display does not have a Inverter (http://www.techsupportforum.com/forums/f108/dell-inspiron-1750-inverter-location-490355.html).
So main question is: if I order a new LCD and change it, will it work?? Don't wan't to go ahead and buy it as Laptop is out of warranty.


----------



## CTSNKY (Aug 7, 2004)

What do you see when you plug it into an external monitor?


----------



## joeten (Dec 4, 2008)

Did you test with a external monitor hook it up and test with the FN buttons brightness etc if it works then it most likely is a lcd issue


----------



## patrulheiro (Dec 11, 2008)

Done all that guys, it works absolutely fine with the external monitor, I did try to increase/decrease the brightness but the black screen still there. You can see the brightness changing, the backlight IS working, just that is no image. Also I can hear Windows login and all, so definitely nothing wrong with motherboard or anything else.

I've seeing some other people with same issue, just want to make sure that changing the LCD will sort it out!


----------



## CTSNKY (Aug 7, 2004)

Never hurts to change out the LCD inverter first....usually much cheaper and easier than the LCD....both may have to be replaced, ultimately.


----------



## patrulheiro (Dec 11, 2008)

CTSNKY said:


> Never hurts to change out the LCD inverter first....usually much cheaper and easier than the LCD....both may have to be replaced, ultimately.


Hi CTSNKY, the problem is that it seems that is no inverter on this LCD (http://www.techsupportforum.com/foru...on-490355.html), would you think different??


----------



## CTSNKY (Aug 7, 2004)

Sorry I missed that bit above......then LED screen replacement it is.


----------



## gwgmer (Sep 27, 2011)

Original poster here: I did end up changing the LCD out, and it didn't work. The problem must have been a faulty connection on the board for me.

patrulheiro: I would still recommend trying to swap out the LCD regardless - as for you it certainly may work. But always keep in mind that a fault on the board is always, always possible.


----------



## joeten (Dec 4, 2008)

gwgmer dang that was a real shame sometimes it can be a real problem diagnosing a board fault


----------



## patrulheiro (Dec 11, 2008)

gwgmer said:


> Original poster here: I did end up changing the LCD out, and it didn't work. The problem must have been a faulty connection on the board for me.
> 
> patrulheiro: I would still recommend trying to swap out the LCD regardless - as for you it certainly may work. But always keep in mind that a fault on the board is always, always possible.


Thanks gwgmer, will give it a try, I had confirmation from another post that one guy with the same problems changed the LCD and it worked ok, so there is still HOPE 
Will post back with the results!


----------



## patrulheiro (Dec 11, 2008)

No dice guys! Receive the new LCD but same problem. Might give Dell a call, wondering if I order a new cable would I get any results??


----------



## nikkioanderson (Dec 3, 2012)

Hey...know this is old but I am now having the same problem. I guess I was hoping you found the solution at some point. How did you fix it/how much did you pay to fix it? I have a new screen on the way but if it turns out to be a board issue should I just sell for scrap?


----------



## gwgmer (Sep 27, 2011)

> Hey...know this is old but I am now having the same problem. I guess I was hoping you found the solution at some point. How did you fix it/how much did you pay to fix it? I have a new screen on the way but if it turns out to be a board issue should I just sell for scrap?


Like I said a bit earlier in the thread, swapping out the LCD didn't work for me, and I'm pretty sure the guy ended up getting a new machine.
This doesn't mean that getting the new LCD won't work for you. Hopefully it will. But if it doesn't, I don't think there's a whole lot you can do.


----------



## patrulheiro (Dec 11, 2008)

gwgmer said:


> Like I said a bit earlier in the thread, swapping out the LCD didn't work for me, and I'm pretty sure the guy ended up getting a new machine.
> This doesn't mean that getting the new LCD won't work for you. Hopefully it will. But if it doesn't, I don't think there's a whole lot you can do.


Agree!
Had the same problem, tried new LCD, new cable but end up being a problem with the motherboard. I'm currently using as a media server where I RDP to it if I have to do any work


----------



## PetranGR (Sep 9, 2014)

Hello to all ,

I have the same problem as all of you said.

My laptop shows in external monitor but NO in the internal.

You turn it on,and you see the "really black" coming on , like the electricity is going through the system.

I have changed panel ,but with no result.
I am waiting for the new cable, to be arrived at my home next week. To see if i get any luck.

The connection of the PKL_LED in the schematics is clear , soldered good.

Any thoughts ?


----------

