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Laptop Screen - what do I need to replace - LCD screen - inverter - actuator switch

Posted on 2010-09-06
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Last Modified: 2012-08-13
Laptop: Acer

Symptoms:
Initially there was a very slight flicker every so often.
Then after a couple of months at boot I would see the first Acer screen but during this screen (3 sec or so) the screen would go black/blank or would turn off and I would not see the BIOS screen or Operating System Choice.  (Computer would however boot properly to windows and windows runs no problem just I could not see anything)
Initially I could push the Lid Actuator switch a couple of times (maybe 20 or 30) and the screen would at some stage stay on.  (I dont know if it matters but as I would release the switch and the screen would not stay on I THINK i could hear a very little hummmmmm which would stop as soon as the screen would turn off which was about a second.)  In any case if I could get the screen to stay on then it would then work until next boot.

NOW at any time while the screen is blank/black I push the Lid Actuator switch then upon releasing the switch the screen can be seen for a second and then turns off again.  When I can see it, it is not dim it appears to be full brightness.  But now no matter how many times I push it I cannot get it to stay on.

When the screen is off I cannot see the contents of the screen at all, even with a bright light so I assume it is not a backlight problem.

I can connect it with a VGA connection to a TV and all works fine.  From the monitor I looked at turning on the laptop screen as a second screen in dual mode for example.  Windows recognizes that a second screen exists, i can set the resolution and then click apply.  The laptop screen turns on for a second then turns off.

So which part do I check, buy first?



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Question by:darbid73
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Tribus earned 250 total points
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I am going to go with the combination of Power Inverter and the LCD possibly bad here.

With the screen not getting any image at all, even with a light behind it, usually means that the LCD is not getting power.  In this case it would be the power inverter.  However it could be both.  The most inexpensive solution would be to try just the inverter.  They are usually about $25.00 - $35.00.  Then try the LCD they should run about $99.00 - $150.00....

I have seen the Inverter be the case on several laptops, and I have also seen it be the LCD only.  Without actually having the physical laptop and testing the LCD with a voltmeter and such I couldn't tell you.  However you can check your LCD with a voltmeter and the inverter and you could narrow it down that way.

Hope this helps...
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by:ErwindeVries
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I hate to say this darbid73 but ur screen is dead....
I guess that the waranty is expired so u should check for a second hand lcd laptop screen for ur laptop.
If you know how to build it in it would save you some money. But if you dont let an expert do it at the computershop.
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by:darbid73
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At this stage I am thinking I am lucky, cause both inverter and screen are replacable.  A video card is not.  

Now to the testing part.  In theory what do I need to do here.

My LIMITED understanding is this

Power > Motherboard > many bits > Actuator Switch > Inverter > Screen

With a voltmeter I test after the Actuator swtich first.  If power is there then it is not the switch.

Then check after the Invertor.  If power here then it is not the inverter.

Thus if power is going all the way through it is the Screen.

Is it that cut and dried?
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by:Tribus
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Pretty much.

You can just test the inverter first and see if you have power.  I have not seen many Actuator switches go bad.

Odds are here though that it is the screen.
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by:darbid73
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Wow you really think it could be screen.  Ok I will not be able to test right now but will try pull it apart tonight (am in europe).

So basically what you are thinking is if I can find current running after the actuator then it is most likely not the actuator and most likely the screen.

The thing is this is now a 2nd computer and prices are higher here than what they are in the US for these things.  A screen here on ebay costs around 250US$.  So I am not excited about getting a screen for it.  I might retire it for good.  If it was the inverter then this is much cheaper and I might try to fix that.
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by:Tribus
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In my experience with these issues, it is usually better to scrap it or tie it to an external LCD.

The cost of new laptops is pretty low these days and putting 200.00 - 300.00 into an old laptop is just not worth it IMO.

I wish you luck on this one...
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by:darbid73
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Thank you.  I will leave the question open till I have actually tested it in case I have some questions on testing or the results.

Then I will end it.

Thank you again for helping-
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by:edbedb
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This one is easy, you will have to replace the LCD panel and it is not difficult to do.
I find it hard to believe that it would cost $250. Unless it is a real odd ball, you should be able to get a new one for much less. What is the model # of the laptop?
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by:darbid73
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Hi edbedb, I really want to share in your confidence, but lets see.  

Cost is about 220US$

see here - I am in Germany.

http://cgi.ebay.de/Original-Acer-Notebook-Display-17-WXGA-Aspire-9520-/350222213870?pt=Notebook_Komponenten&hash=item518adee2ee

I might be off to China soon so maybe I can get one there somewhere.
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by:edbedb
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by:darbid73
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are they really the same? What specs or things do I have to match up?
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by:edbedb
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It's best to remove the screen to get the part number, for example LP171WP4.
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by:darbid73
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Ok pulled my laptop apart.  I hope I get it back together again.

So it is an AU Optronics screen with part Number B170PW04 V.0

I have not worked out how to get the voltage though as I cannot see anything exposed to test on.
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by:Dutchguy000
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http://www.pchub.com/uph/laptop/358-28717-6014/AU-Optronics-B170PW04-V.0-17-TFT-LCD.html

Found this on quick search.

Just wanted to add, it may be a good idea to remove the battery during any repairs.  Don't know about Acer but some laptops I've repaired can short out even more components when reconnecting the screen's powers.  Just a thought.  
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by:darbid73
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ok guys here is a photo of what i can see.

we pulled these two connectors off and connected each one to a voltmeter.

I am not 100% sure what I am doing with the LCD but we connected up to each one.

The voltmeter does not show anything.  If I press the actuator on and off then for both connections the voltmeter springs to life with a response, but then goes back to 0.  

Thoughts suggestions.  I have having trouble testing on the other side of the inverter.
photo.jpg
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by:darbid73
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Dutchguy thank you very much for adding that.  I am not sure it will be useful as I am in Germany, but thank you anyway.  I am still not 100% sure that it is the LCD.

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by:Tribus
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What you need to do to test the other side of the inverter is to pull the cable from the side that goes to the LCD then test the leads on the inverter.  If you have power at the output of the inverter then the part is working correctly.  You can also cut a bit of shielding off the wire (not recommended) and test then seal it up after.

This is always a tough situation....

I hate to say this again, but try replacing the inverter/actuator first.  This will be the easiest way to narrow down your options.  I still think it's the LCD itself though...:( .

You could take the LCD to a electronics shop and ask about it or get it tested since you are not fully familiar with testing these parts yourself.
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by:edbedb
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I was afraid of that. Your screen has dual baclights. The best price I could find delivered is this at $200
http://cgi.ebay.com/AU-OPTRONICS-B170PW04-V0-LAPTOP-LCD-SCREEN-17-DUO-/140449754670?pt=LH_DefaultDomain_0&hash=item20b3752e2e
You can get one with a single backlight that is supposed to be compatible for about $40 less.
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by:darbid73
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The photo above is as you guys know the LCD side of the inverter.  The other side has a single multipin connector.  

I cannot see which is the power.

So I have gone back to where the Actuator joins up with the laptop.  I get a constant current there and then when I press the actuator the current is cut to nothing.  So I think I am happy that the actuator is working correctly.  

It seems like there are a number of screens that should do the job I hope.  a second hand one from someone private is very cheap.  So I am thinking about getting a converter, I might even order one from HK or China as they seem really cheap there.

I really appreciate you all working with me on this.  My laptop which was once my pride a joy is looking really sad.  I have although learnt a lot, like how to take a laptop apart.  I was a virgin.
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by:darbid73
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I hope to pick up an inverter today so I will then know what is going on here.
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by:Tribus
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If it doesn't work then you can return the part and know that the LCD is the issue, or you can keep it for a spare, or use it...lol.

Anyway, good luck!

-Tribus
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by:darbid73
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And it is just my luck, a new inverter has not helped at all.  So people.  I assume I have to buy a new screen.  That is all i can do right?
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by:edbedb
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Like I said last week "This one is easy, you will have to replace the LCD panel and it is not difficult to do".
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by:darbid73
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yeh yeh adbedb it is not that hard.  Just expensive cause it is 17" and has 2 backlights.

I actually did not think it was the LCD because most people say an indication of the LCD going bung is that you can shine a bright light on the screen and still see things.

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by:edbedb
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Actually, that is an indication of a bad inverter or backlight. That's why I knew that a new inverter wouldn't do it.
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by:edbedb
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You can get a replacement screen that has only one backlight and a matching inverter for that model.
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by:darbid73
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I am interested and listening.  How.

I have no idea what I am doing.  All that I know is that the technical manual lists 3 LCDs

2 of them are
B170PW04 V.0
LP171WP4 TL02

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by:edbedb
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by:darbid73
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yeh that good.  But I am pretty good at that kind of stuff.  USA / China /HongKong there are some great prices but I have got stuck with paying all the taxes here before.

What I would prefer to know is what are the model numbers of other LCDs that will work ok.
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by:edbedb
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What I would do is search for a WXGA 17" 1440 x 900 LCD. If there is enough difference in price, i would go ahead and take a shot on it. If it doesn't work, I would just put it in stock. That is probably not something you would want to do.
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by:darbid73
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ok but what is the story with the dual lamps.

There are plenty of these LP171WP4 here but they all seem to only have one lamp.  Can I just connect up one power cable to the inverter and it will work the same?
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by:edbedb
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I don't see why it wouldn't but I never tried it.
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by:Tribus
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Unfortunatly, this is the dilemma with laptops and bad screens.

My personal recommendation to my clients in this case is to go ahead and get a new laptop and refer the old one to an external LCD.  For about $400.00 - 500.00 you can get a decent laptop these days.

That's just my advise on fixing LCD issues in most cases with expensive replacement LCD's.

Here is the site that I have used in the past to find cheap replacements:

http://www.screenaid.com

Hope this helps...

-Tribus
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by:Tribus
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Added thought...

If you buy a single backlit screen, you should also buy the matching inverter as well as the dual backlight inverter might put out more voltage and blow the new screen immediately.
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by:darbid73
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I think we have flogged this questions enough.

Looks like I have to get a new screen.  I am not really interested in trying different screens so I will hold out for ebay to have a B170PW04 with dual lamps to come up.  Second hand people only get less than 40€ for these parts.

Thank you very much to both of you.  I only have 500 points right now so I can only share it 50%.  

When I get a new screen maybe I will have a new question.
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by:Tribus
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No problem man, that's why we're here!

I wish you luck...
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by:darbid73
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Hi guys, I have a related question to this and have made a new question.  The screen is flickering again.

New Thread Here
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