What part of the motherboard on a laptop controls the vertical and horizontal lines/size of the laptop screen display?
Laptop Screen
- Thread starter oniq
- Start date
Well, on a desktop you can adjust all those things right on the screen, on a laptop you can't. Or is this just not possible? My screen is messed up, there is a white line going through the lower portion of it (its about half an inch thick) and the top 3/4 of the screen have the image of whatever is running. Below the line, 3/4 of it are the image from the top. The other 1/4 below and above the line are black. I'm wondering if this could be fixed somehow by adjusting something. I received this laptop from a friend, and he said he was playing around with the motherboard (there are two coils that he touched on the motherboard). What a dumbass huh? lol. Well, I figure there might be some way to fix it, other than the screen problem it is a sweet little machine. It's a Sony VAIO, by the way. If you can help in anyway, I'd appreciate it. Thanks.
That problem is related most often to a broken flex strip between the LCD and the motherboard, or faulty/dry joints on the connectors between the LCD glass assy itself to the signal distribution DeMUX boards on the back of the LCD itself...
Without excellent surface mount soldering skills you will not be capable of repairing it yourself.
Without excellent surface mount soldering skills you will not be capable of repairing it yourself.
You can determine if its a dry joint in the LCD casing by removing the display assy from the laptop screen bezel and gently pressing the front and back of it with your fingers around the edges. That will help narrow where the dry joint is if its in the LCD. Now the tricky part comes in, see the 6-12 dark bronze colored strips going into the glass? If you can see tin wires coming out of them and soldered to the board, that will most likely be your problem; one or more of them wires has broken. I'll get a laptop screen scanned tomorrow and point out exactly what happens and how to fix it.
Remember you must be an absolute EXPERT with surface mount soldering to attempt this repair otherwise you will most likely permanently ruin the LCD assy.
Cheers
Remember you must be an absolute EXPERT with surface mount soldering to attempt this repair otherwise you will most likely permanently ruin the LCD assy.
Cheers
Sorry I haven't done this earlier but here is some info to help out
These pictures are from the LCD panel out of a Toshiba Satellite Pro 410CDT and is one example of an LCD that is often repairable.
Note that the inexperienced will most likely totally destroy their LCD screen assy if they do not know what they're doing, in other words, do what I describe here entirely at your own risk!
Take the battery out and ensure no power is in the laptop. The screen has high voltages, over 1000 volts inside if powered on.
READ THROUGH the whole document first; some laptop screen assy's may not require any disassembly at all, sometimes the flex connectors are in full view (perhaps underneath a plastic sheet to electrically protect them).
Take apart the screen housing of the laptop, most laptops have at least two screws near the hinges under a stuck on rubber or label. Some have them on the side as well. To assist in the removal of the label without damaging it, find a scalpel or very sharp pointy knife and heat the panel up with a hairdryer - this melts the glue (and also aids in the temporary removal of "Warranty Void If Removed" stickers too
). Dont heat it up too much because you can melt the plastic housing on some laptops, so I've learned the hard way
To get the front part of the housing apart from the rear part, they're almost always held in with clips, with the exception of some IBMs (such as the 380 series) that the front panel slides upward after removing two small retainer components next to the two screen clips that hold the screen closed to the notebook. The best way to get these apart is to lift the plastic surround next to the screen and wiggle it - many clips come off effortlessly - DO NOT use a small screwdriver and attempt to wedge it apart, it leaves unsightly marks.
Once you have it apart, usually 4 screws hold the LCD assy inside the screen housing. Remove these screws and carefully lift the LCD an inch or two and you will see (most often) two or more plugs going to the screen - one or more ribbon/flat cables will be data and the two thick silicon cables are the high voltage for the LCD CCFL (Cold Cathode Flourescent Lamp). Using a small flat screwdriver, wedge out one side at a time of the high voltage cable socket on the inverter board (usually a purple and white wire). Next remove the data cable going to the LCD - this may be a micro-centronics type interface or an edge connector or a flat ribbon connector. First thing to do is to re-attach every cable and put two screws on opposite corners of the LCD assy to see if it was a poor contact causing the problem. Turn it on while keeping your hands very far away from the LCD housing to avoid electric shock. If the problem is still there then you'll need to disassemble the LCD assy to get to the LCD panel.
This I cannot describe as there are literally hundreds of different types around but more often than not the seperate components are held together with a few tiny screws and parts of the aluminium surround bent into a position so it doesnt fall apart. YOU MUST wash your hands and put on cotton gloves when you take apart the LCD and have a large bench so you can reassemble it again. WARNING: The LCD contains a Cold Cathode Flourescent Lamp which contains Mercury and other poisonous chemicals! You are at high risk of poisoning if this lamp breaks and must take extreme care to ensure it doesnt!. The lamp is usually where the wires come out of, some LCDs have two lamps but they are few and far between. Do not force anything; sometimes parts of the housing are glued together; it is up to the individiual to determine if you should proceed. Remember heat softens most glues but it must not exceed the heat where your fingers start feeling pain from the heat or you are likely to damage it. Remember, if you are heating around the glass of the LCD, ensure you uniformly heat the whole glass as it expands as it gets hot and can crack the LCD if you only heat part of it.
Once you have it apart, do not pull out any of the light diffusing/spreading sheets from it, simply remove the LCD assy - many times it will have plugs attaching one board to another and most often they're micro-centronics or edge ribbon type connectors. Once you have the LCD out, the fun begins
If you can see the wires going from the multiple flex strips to the board then you are possibly in luck - if the flex strips are IR-soldered to the board then you're out of luck. Look with a good magnifier at the part of the screen where the fault was and see if any of the solder joints have broken away from the board. You will need a soldering iron of about 270-340 degrees celcius. Using the scalpel, VERY GENTLY scratch the surface of the wires coming from the flex strip so solder adheres to it. Then get the soldering iron and solder it to the circuit board pad. Do again for each one that is broken. Note sometimes the break occurs between the wire and the flex strip - in that case you are out of luck.
When finished, reassemble and perform the smoke test, if it smokes then it failed, if it doesn't smoke you may have fixed it! Good luck!
LCD1
LCD2
These pictures are from the LCD panel out of a Toshiba Satellite Pro 410CDT and is one example of an LCD that is often repairable.
Note that the inexperienced will most likely totally destroy their LCD screen assy if they do not know what they're doing, in other words, do what I describe here entirely at your own risk!
Take the battery out and ensure no power is in the laptop. The screen has high voltages, over 1000 volts inside if powered on.
READ THROUGH the whole document first; some laptop screen assy's may not require any disassembly at all, sometimes the flex connectors are in full view (perhaps underneath a plastic sheet to electrically protect them).
Take apart the screen housing of the laptop, most laptops have at least two screws near the hinges under a stuck on rubber or label. Some have them on the side as well. To assist in the removal of the label without damaging it, find a scalpel or very sharp pointy knife and heat the panel up with a hairdryer - this melts the glue (and also aids in the temporary removal of "Warranty Void If Removed" stickers too
). Dont heat it up too much because you can melt the plastic housing on some laptops, so I've learned the hard way To get the front part of the housing apart from the rear part, they're almost always held in with clips, with the exception of some IBMs (such as the 380 series) that the front panel slides upward after removing two small retainer components next to the two screen clips that hold the screen closed to the notebook. The best way to get these apart is to lift the plastic surround next to the screen and wiggle it - many clips come off effortlessly - DO NOT use a small screwdriver and attempt to wedge it apart, it leaves unsightly marks.
Once you have it apart, usually 4 screws hold the LCD assy inside the screen housing. Remove these screws and carefully lift the LCD an inch or two and you will see (most often) two or more plugs going to the screen - one or more ribbon/flat cables will be data and the two thick silicon cables are the high voltage for the LCD CCFL (Cold Cathode Flourescent Lamp). Using a small flat screwdriver, wedge out one side at a time of the high voltage cable socket on the inverter board (usually a purple and white wire). Next remove the data cable going to the LCD - this may be a micro-centronics type interface or an edge connector or a flat ribbon connector. First thing to do is to re-attach every cable and put two screws on opposite corners of the LCD assy to see if it was a poor contact causing the problem. Turn it on while keeping your hands very far away from the LCD housing to avoid electric shock. If the problem is still there then you'll need to disassemble the LCD assy to get to the LCD panel.
This I cannot describe as there are literally hundreds of different types around but more often than not the seperate components are held together with a few tiny screws and parts of the aluminium surround bent into a position so it doesnt fall apart. YOU MUST wash your hands and put on cotton gloves when you take apart the LCD and have a large bench so you can reassemble it again. WARNING: The LCD contains a Cold Cathode Flourescent Lamp which contains Mercury and other poisonous chemicals! You are at high risk of poisoning if this lamp breaks and must take extreme care to ensure it doesnt!. The lamp is usually where the wires come out of, some LCDs have two lamps but they are few and far between. Do not force anything; sometimes parts of the housing are glued together; it is up to the individiual to determine if you should proceed. Remember heat softens most glues but it must not exceed the heat where your fingers start feeling pain from the heat or you are likely to damage it. Remember, if you are heating around the glass of the LCD, ensure you uniformly heat the whole glass as it expands as it gets hot and can crack the LCD if you only heat part of it.
Once you have it apart, do not pull out any of the light diffusing/spreading sheets from it, simply remove the LCD assy - many times it will have plugs attaching one board to another and most often they're micro-centronics or edge ribbon type connectors. Once you have the LCD out, the fun begins
If you can see the wires going from the multiple flex strips to the board then you are possibly in luck - if the flex strips are IR-soldered to the board then you're out of luck. Look with a good magnifier at the part of the screen where the fault was and see if any of the solder joints have broken away from the board. You will need a soldering iron of about 270-340 degrees celcius. Using the scalpel, VERY GENTLY scratch the surface of the wires coming from the flex strip so solder adheres to it. Then get the soldering iron and solder it to the circuit board pad. Do again for each one that is broken. Note sometimes the break occurs between the wire and the flex strip - in that case you are out of luck.
When finished, reassemble and perform the smoke test, if it smokes then it failed, if it doesn't smoke you may have fixed it! Good luck!
LCD1
LCD2
Hey, thank you so very much for the response I'm going to look into it now and post on my findings/success . I very much appreciate your help, its hard to find people like yourself that actually go out of there way to help someone. Thank you so much!!!!!
. I very much appreciate your help, its hard to find people like yourself that actually go out of there way to help someone. Thank you so much!!!!!I was able to take the screen apart and see if there was anything wrong. Everything was seated correctly and nothing looked burnt out. I'm wondering if this could be a problem not with the actual screen but with a chip on the motherboard? Is there anything else it could be? Thanks again.
OK, since you have obviously checked the continuity of every pin on the flex connector between the motherboard and LCD and found no problems there, and have gone through the trouble of putting a CRO on each input to the LCD on the DeMUX board and verified that on some pins that NO SIGNAL is getting there, resulting in the problem you describe, well then perhaps you can get cracking on the board level repair of your laptop. After obtaining a circuit diagram from the manufacturer (ha ha ha) begin by calculating which pins on the multiplexer trace through to be demultiplexer on the board on the rear of the LCD assy that could cause a problem like you describe. After finding which pins do what, you need to trace back to the digital video output IC and work out where the signal is being dropped or corrupted. After you have extablished that it is a particular IC, contact the manufacturer of the IC and see if they will sell you the particular IC in a quantity less than 1000 devices. By this stage you should be fairly certain that the problem does not lie in a broken through connector or track or dry solder joint. Also be certain that it is not a leaky/short circuit coupling capacitor on the board (this can be figured out by studying the circuit diagram that you obtained from the laptop manufacturer). You should be ready to use a SMD desoldering kit to remove the faulty IC, remove it using the technique you have gained over years of practice, clean the board using 99.5% pure isopropyl alcohol, apply some soldering flux to the board, attach two opposite end pins with the soldering iron and using your SMD reflow resoldering kit, resolder the remaining pins. Get a magnifier out and ensure you haven't bridged out any pins. Clean the board and switch it on. Congratulations! you should now have a working laptop! (BTW - With that fault you describe, I have NEVER had anything other than the LCD or flex cause the problem)
No offence intended here but it really sounds that this repair is very far out of your league. If somebody else can prove me wrong otherwise then please be my guest. I guess I can be called an expert on the workings of the electronics going to screens as I've studied the repair (and workings - electrical timings, protocol etc) of many to gain an understanding. What I've learned is you cannot repair more than you actually can. I can be almost 100% certain your problem lies in either the flex between the screen and mainboard OR the screen itself.
No offence intended here but it really sounds that this repair is very far out of your league. If somebody else can prove me wrong otherwise then please be my guest. I guess I can be called an expert on the workings of the electronics going to screens as I've studied the repair (and workings - electrical timings, protocol etc) of many to gain an understanding. What I've learned is you cannot repair more than you actually can. I can be almost 100% certain your problem lies in either the flex between the screen and mainboard OR the screen itself.
Thanks for the reply, I'm actually the "middleman", my dad is working on the laptop but has various experience with electronics. He'll look into it as you angered him with your reply (LOL jk), but maybe now he will fix it. You looked at the picture that I posted, right? Thanks for all the help.
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