Solved

Blank screen on Dell Inspiron 1545

Posted on 2011-03-05
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Last Modified: 2012-05-11
Hi
I have been brought in a Dell inspiron 1545 laptop for a screen replacement, the old screen was cracked but still working.  ever since I installed the new LED screen I have not managed to get anything on the screen at all when I boot-up the machine.  I thought I might have damaged the cable that connects the screen to the mainboard so I have replaced this cables twice with a new one but still no joy, I have also installed two new screens but still nothing, I installed the cracked screen which was working before I removed it, this is also showing no signs of Life.

I have booted-up the machine with an external monitor connected and it boots up no problem at all, I have also pressed the FN key along with F1 key which toggles between the external monitor and the laptop screen - external monitor works fine but still nothing on the laptop screen.

any help in resolving this will be greatly appreciated

jag
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Question by:140160
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by:edbedb
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Are you sure you can't even see a very faint image? You might e3even need a flashlight to see it.
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by:140160
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Hi
No faint image at all even with a flashlight, these new LED backlit screens don't have a inverter.

jag
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by:asidu
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Check the micro switch on the PC if there is one. It could be sticky and cause a light up issue.
You could manually operate it to see if power comes on to the screen.

Also check the connector on the main board. Are the pins OK is the connector sitting into the position comfortably.
If you fixed back the old LCD screen, you should be able to see something.

Since you still get out put to the external monitor it means the machine is working.
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by:edbedb
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Sorry, I didn't know it was LED.

You said "I have also pressed the FN key along with F1 key which toggles between the external monitor and the laptop screen"

I believe you should just press the F! key without the Function key.
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by:Grant1842
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Use a digital multimeter to check your cables to be sure they are good.
Make sure the ends are seated proberly .

All so check the screen  switch .
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by:140160
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Hi

I have checked for a microswitch - there doesn't appear to be one. the cable to the mainboard is secure and is brand new,  apart from no image on screen, the laptop appears to be working normally.  I have checked the screens in other laptops and they are working OK, I cant understand why I am getting absolutly nothing on any of the screens.

jag
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by:asidu
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Was the original screen also a LED screen?
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by:140160
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Hi

Yes the original screen was a LED screen

jag
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by:asidu
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Jag, you have changed new cables for the LED screen.
New LED screen does not work with 1545 Dell.
Out put to external monitor is okie.

Have you also confirmed that the function key for alternating the out
put to the external monitor and internal screen is okie.

Apart from the data cable is there a cable which supplies power to the screen.
Check it and ensure that power is delivered to the screen.

Your observations indicate that the video output is having an issue.

With the service tag check the detailed spec from the dell site.

Since there is no mechanical switch on the base unit. The screen would use
a magnetic switch to operate a reed relay when the screen is closed. It could be
that this switch is faulty.
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alarmrepairman earned 500 total points
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Hi, Hope this helps you to fix this problem. LED screen fix.

My theory is that when the screen is damaged it draws to much current, possibly momentarily and it blows a fuse on the motherboard.

To find it look with a magnifying glass near to the screen connector. To do this you will have to remove the keyboard or move it to the side (assuming you have the laptop in bits with the screen already removed) fu. The keyboard ribbon cable connectors are well tricky to get back in place if removed fully.

You are looking for a small "surface mount 3amp fuse". It says F1 on it. Its a small oblong device with a solder pad at each end.

To confirm its blown get hold of a multimeter and touch the probes on each end. If you don't get low ohms reading or a beep if using the continuity test its almost certainly blown.

You can buy these from electronic supplies such as Farnell in the uk LITTELFUSE|0451003.MRL|FUSE, QUICK BLOW, SMD, 3A | Farnell United Kingdom

You will however need a small soldering iron, good eyesight/magnifier and a decent light source.

Unsolder and replace the fuse (or short out with a bit of wire for a quick test to confirm but don't leave like this as it could cause damage to the motherboard if the screen went again - fuses are there for a reason - protection)

Post if it works for you.
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by:140160
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Hi

Thank you for this, I was going to completely dismantle the machine this weekend to have a good look around it, will look for this fuse will report back  monday.

Jag
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by:alarmrepairman
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Hi Jag,

If you need a picture to show you the fuse if not sure then take a look at my posting on this link  http://forum.notebookreview.com/dell-inspiron-dell-studio/478489-inspiron-1545-led-screen-no-backlight-2.html

Look at the guys after my initial posting and you will see that some have placed picture links to double check the position.

Good luck
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by:140160
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Hi
Thank you so much for taking the time to help, Have checked this fuse and it is definitely blown, a new one has been ordered. I would never have found this without your help. saved anopther laptop from the junk heap

Thanks again to everybody else who also responded

Jag
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