There's nothing that obvious when looking for dry/cracked joints. and L781 looks good from here....Of course I'm not a regular at soldering, but this doesn't seem to be my problem. (mine went white after cofiguring a new PC, now it turns white on all PCs..) Maybe it was directly related to the new video card...
I took the monitor to an experienced technician in the medical field (repairs bio-medical equipment of all kinds) He picked out a few "blobs" of solder as well as went over the L781 inductor someone out here mentioned. It now WORKS PERFECTLY, no more white screen and I immediately got my self test display when I turned it on. THANK YOU fixya and all those who posted. I just saved $200 on a new display.
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Re: Case open, looking for bad solder
This is how to check what's wrong with your LCD monitors. Firstly, power on both CPU and monitor.
After it went white, you have to check that if you can see the image on the
screen or not by shining a flashlight into the screen, not directly but find the best
angle to the screen and take a look very closely. If you can see the icons or
any image, there will be a minor problem. Like me, I can see window image using
flashlight and check lamps inside. Some of them were broken and it is easily
replaced. If you cannot see anything on the screen, there'll be some problems
with inverter board. If you have soldering tool and want to fix it by yourself,
check the caps first. It may cause this problem. Some caps might show leaking
or burn spot on the board because of too high temp. If you don't have soldering
tool, you better go get a technician to do so.
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Well, that looks like you have what we call a dry joint on the power supply connector of your monitor. With experience , i have discovered this to be a normal problem. Get a compute technician to open up the monitor for you and then take a closer look at the circuit board where the power supply is connected. Check for any dry joints (this means that there is a component on the circuit board that is directly related to power supply, and it is not properly attached to the board (soldered). Notice all the dry joints and use a soldering gun to put them back together and try to power the monitor. Check also for bulged or leaking capacitors. Replace them with the same type
Sometimes our electronics appliances like TV monitor, radio or any other stuff may have a very simple problem. If we are not aware of this then we go in circles looking for the problem.<br />Technicians sometimes refer to this as intermittent problem. Sometimes the system will work and sometimes it will not. A tap/knock may get it working or will stop it from working.<br />Dry-solder joint is one of the causes.<br />If you are a novice and have no idea about electronics and how to work with soldering irons and electricity; please get assistance from a professional.<br />1. Switch off power.<br />2. Open the system up.<br />3. Discharge components which might hold charge to avoid electric shock.<br />4. Look at the bottom of the printed circuit board (track side of the PCB). You might need a hand lens for a closer look.<br />5. Look for cracks in the soldered components. Sometimes shaking components easily helps in identifying these cracks.<br />6. Once you get to know this, get your soldering iron, remove the old solder and re-solder the component.<br />7. You might be agitated to switch on and check your system at this point in time. Don't!!<br />8. Try and look for all the dry solder joints.<br />9. Fix as much dry solder joints as you can find.<br />10. Clean your board. Use isopropyl or general purpose thinner.<br />11. Double check the track side. There should not be any shorts that you may accidently done while soldering.<br />12. Once you are sure all is safe, assemble the system.<br />13. Connect a <span>series lamp</span> to the system and switch on to check.<br />14. If the problem stops; good for you. If it persists then continue looking for and treating dry solder joints.<br /><br />I will share more on series lamps in my next tip.<br /><br />Enjoy<br />Rjn<br /><br />
You may have either the DC filter caps problem or the back light inverter board has failed, worst case will be bad lamps assembly. So check for 12vdc on the inverter board, bad caps with leaking/bulging top, bad solder joints. Most common failures in the LCD monitors are bad capacitors (bulging top/seal or leaking) in the power supply, blown fuses, poor solder joints, failed inverter circuits (blown fuse, shorted transistors, shorted/open transformers), bad lamps (poor solder connections or worn out lamps). You will need to open it up and inspect the inside, see example of failed monitors to get some ideas what to look for: http://s807.photobucket.com/home/budm/allalbums Post back what you see inside so we can guide you further and it will help out other people in the future also. http://en.wikipedia.org/wiki/Capacitor_plague
There are four tabs at the bottom edge of the case tha needed to be release to open up the case. Most common failures in the LCD monitors are bad capacitors (bulging top/seal or leaking) in the power supply, blown fuses, poor solder joints, failed inverter circuits (blown fuse, shorted transistors, shorted/open transformers), bad lamps (poor solder connections or worn out lamps). You will need to open it up and inspect the inside, see example of failed HP monitors to get some ideas what to look for: http://s807.photobucket.com/home/budm/allalbums Post back what you see inside so we can guide you further and it will help out other people in the future also. http://en.wikipedia.org/wiki/Capacitor_plague http://www.badcaps.net
This is a common indication of bad filter capacitors on the power supply board. Below is a picture of the power supply board with the problem capacitors circled in yellow. The repair is easy, you just need to replace those capacitors and the unit should be as good as new. Below the picture is also a link to a full repair guide showing how to dis-assemble the monitor and what parts need to be replaced. the repair guide has a full parts list for the job.
If you can open and removed the power supply/inverter board you can check the caps for obvious damage. *(leakage or swelling)
You can pull the offending cap or just do what I did and replace ALL the caps on that part of the power circuit. It isn't expensive and the board is big enough to handle soldering without a lot of hassles.
I did this for an old Dell monitor this past week and it is up and running!
Nice and bright too.
When you open up the monitor, there will be a main board on the bottom. Look at the solder joints and see if you can spot any that have hairline cracks in them. You may have to look at the different solder joints with a magnifying glass to spot them cause they might be hard to see.
When you find them, take the solder off by placing your solder wick on the solder joint and then put your soldering iron on top so it heats up the solder and it melts into the solder wick. After you do this then put fresh solder on the solder joint.
Do this with all solder points that you find cracks in them.
If the screen is all white light then you can have a number of problems.
One could be a bad video board, the next could be a simple loose wire
from the video board to the back of the lcd screen OR a simple blown
fuse on the back of the actual lcd screen can cause the same thing.
Snaps are all sround these things and can be really stubborn at times.
Best to start the bottom first then work up each side to the top.
Something flat, thin and with a decent sharp edge on it will help. A
pocket knife held parallel to the joint between the front and rear
plastic works, you can also sharpen the edge of an old credit card with
a file (nail file works) This isn't as strong as a blade , but safer if
you slip !!
The E151FPb's seem to have a problem of this sort. After doing some research online I've found that the most common problem is a few dry solder joints on the large circuit board inside the monitor. There was also some talk of a connector suffering from heat creep that sound be connected better on the inside, but usually that would make the screen turn black if it were to become disconnected. The monitor can be opened by unscrewing all the screws on the back, there should be 6 screws you need to pull out before being able to open the case. After those, insert a thin, but strong piece of metal into the side and sort of twist/slide it along the side and it should pop open some clips and just work your way around the perimeter. After that it's just some simple and obvious screws to get to the circuit boards.