E228WFP display disappears

I acquired one of these monitors with the back light issue.  After replacing R821 with a 470K resistor the monitor no longer shuts off, but I am having an issue which I seen posted earlier of the left side of the screen goes darker than the right half.  I have tried running the screen with a screen saver for several hours, and the problem still persists.

Has anyone had this issue, and come across a solution or work around?

I know this thread is very old and I'm probably reviving a Zombie Thread, but I wanted to post about what I experienced so other people in the future who run into the same issue can get as much from this thread as they can. I have a few of these monitors (E228WFPc) at work and they were on their way to recycle when I asked about them. My boss said if I can make them work I can have them. That's when I came across this thread.

I only had a 430K resistor on hand so that's what I used in the first one (I've only completed one to date). I soldered it on top of (in parallel to) the existing R821 and fired her up. To my great joy it worked and stayed on longer than the ten minutes it would before. I am ecstatic because now I have a dual monitor setup at work. My soldering job isn't pretty, but it is doing what it should:

http://i1251.photobucket.com/albums/hh560/postal302/Computer%20Issues/P1030186.jpg

I did notice by the end of the first day that the left side of the monitor gradually became quite a bit darker than the right. While the monitor was still usable, it was rather annoying. I attempted to recreate what it looked like:

http://i1251.photobucket.com/albums/hh560/postal302/Computer%20Issues/SideDim.png

I have a theory on this but it's merely guessing. Before the resistor was added a part of the circuit would fail causing the backlight to shut off. Now with the added resistor, the weak part of the circuit still fails when it gets too hot, but the added resistor overcomes the disconnect and keeps the backlight lit, however since the circuit has been modified it is not correct to keep the backlight lit properly and this causes the uneven lighting.

The next day, after the monitor had cooled overnight, I turned the backlight down (to 65) thinking that less current draw into the lights would cause less heat. This seemed to work quite well because it wasn't until after using the monitor for about four hours that I noticed the left side of the monitor going dark and it didn't seem to get as dark as before.. Again after leaving the monitor off all night, I removed the plastic back cover and left it off because it seemed to be insulating the monitor and keeping the heat in. This worked because after a full day the monitor kept even lighting. I modified the back cover of the monitor by removing some of the plastic vertical "slats" on top and bottom of the monitor to allow better airflow and thus far has been working great!

My summary, install a resistor on top of (in parallel to) R821, but also do what you can to keep the monitor cool.

I know this thread is very old and I'm probably reviving a Zombie Thread, but I wanted to post about what I experienced so other people in the future who run into the same issue can get as much from this thread as they can. I have a few of these monitors (E228WFPc) at work and they were on their way to recycle when I asked about them. My boss said if I can make them work I can have them. That's when I came across this thread. I only had a 430K resistor on hand so that's what I used in the first one (I've only completed one to date). I soldered it on top of (in parallel to) the existing R821 and fired her up. To my great joy it worked and stayed on longer than the ten minutes it would before. I am ecstatic because now I have a dual monitor setup at work. My soldering job isn't pretty, but it is doing what it should: http://i1251.photobucket.com/albums/hh560/postal302/Computer%20Issues/P1030186.jpg I did notice by the end of the first day that the left side of the monitor gradually became quite a bit darker than the right. While the monitor was still usable, it was rather annoying. I attempted to recreate what it looked like: http://i1251.photobucket.com/albums/hh560/postal302/Computer%20Issues/SideDim.png I have a theory on this but it's merely guessing. Before the resistor was added a part of the circuit would fail causing the backlight to shut off. Now with the added resistor, the weak part of the circuit still fails when it gets too hot, but the added resistor overcomes the disconnect and keeps the backlight lit, however since the circuit has been modified it is not correct to keep the backlight lit properly and this causes the uneven lighting. The next day, after the monitor had cooled overnight, I turned the backlight down (to 65) thinking that less current draw into the lights would cause less heat. This seemed to work quite well because it wasn't until after using the monitor for about four hours that I noticed the left side of the monitor going dark and it didn't seem to get as dark as before.. Again after leaving the monitor off all night, I removed the plastic back cover and left it off because it seemed to be insulating the monitor and keeping the heat in. This worked because after a full day the monitor kept even lighting. I modified the back cover of the monitor by removing some of the plastic vertical "slats" on top and bottom of the monitor to allow better airflow and thus far has been working great! My summary, install a resistor on top of (in parallel to) R821, but also do what you can to keep the monitor cool.

I have been monitoring this thread since my last posts, but due to other priorities I have been at a standstill on this matter. I have 6 or 7 of these with the same problem as you describe, but have not had the time to resolve it.

 I Believe the problem has something to do with the OLP (Over Load Protection) Circuit but being caused by a malfunction somewhere in the circuit which the R821 modification (Paralleling with 500K resistor) just overrides which is still trying to shut off the Tl494i. Which means there is either an overload somewhere in the circuit or a faulty component creating an off balance in the OLP system. the only part i can identify that would shut down one side of the Backlight and not the other is one side of the D806 and D808 diodes or R831, R833, R838, R840

But it is unlikely because that would mean that R831 and R838, or R833 and R840 would have to fail and not the other two.

But the same thing is the case with D806 and D808. Why would one side of both fail at the same time?

Manufacturing defect for 1 (which has been a high possibility from the start of this whole thing) and rules out the above mentioned resistors.

Another reason this makes sense is that (as Postal302 described) it works fine when it is cool and as it heats up gradually gets worse can point to the Diodes which have that characteristic when failing because of the components they are commonly made of.

Most electronics that are overloaded will get hot or pop like a fuse since there is not any obvious damage to the board even after modifying the circuit with a 500k or similar which seems to override whatever is shutting it down prematurely it likely means that a part in the safety or protection circuit is at fault.

When I checked the original R821 Which is 1 M ohm it read 996 K ohm which is well within tolerance suggesting that it is not the problem.

The D806 and D808 Diodes are BAW56, you can google BAW56 for datasheet and Digikey should have them in

stock BAW56FSCT-ND

Note: if you replace D806 and D808 there should not be any need to modify R821 (Default 1M ohm 1/10 watt or 105) .

Please post your results, Thanks for your input.

But it is unlikely because that would mean that R831 and R838, or R833 and R840 would have to fail and not the other two. But the same thing is the case with D806 and D808. Why would one side of both fail at the same time? Manufacturing defect for 1 (which has been a high possibility from the start of this whole thing) and rules out the above mentioned resistors. Another reason this makes sense is that (as Postal302 described) it works fine when it is cool and as it heats up gradually gets worse can point to the Diodes which have that characteristic when failing because of the components they are commonly made of. Most electronics that are overloaded will get hot or pop like a fuse since there is not any obvious damage to the board even after modifying the circuit with a 500k or similar which seems to override whatever is shutting it down prematurely it likely means that a part in the safety or protection circuit is at fault. When I checked the original R821 Which is 1 M ohm it read 996 K ohm which is well within tolerance suggesting that it is not the problem. Note: if you replace D806 and D808 there should not be any need to modify R821 (Default 1M ohm 1/10 watt or 105) . Please post your results, Thanks for your input.

I had my monitor "fixed" with replacing R821 with 470 kOm resistor, but I noticed that the left side was brighter than the right one. 

I reverted R821 back to 1MOM and replaced both D806 and D808, that didn't help - monitor is exactly the same state as it was before any repairing.

jammtek, do you have any other suggestions we could try?

Thanks for posting the workarounds.

The culprit is a capacitor(C806) that is defective and causes the system to fail as the temperature rises. The cap is a 1uf 16v non polarized capacitor

I confirm - monitor has been working after I had C806 replaced. I had a 1uf 50v (just a coincidence :) ) ceramic capacitor and it did the trick. Monitor brightness is even.

Thanks a lot!

Good, my replacement capacitors have not showed up yet, but it is good to finally get this solved.

I intend to post detailed instructions (with pictures) on how to fix this problem.

I also confirm this. I have replaced the R821 with 500k and the monitor worked accept for the backlight, now with jammtek's solution my backlight is perfect!

Thanks guys.

I can confirm C806 IS the problem. I am not very good at removing small caps so I just soldered a 1uf 50v cap that I got at RadioShack to the original one and monitor is running perfectly now for over 12 hours.

Same here, soldered a 1uf 100v cap over the C806 , monitor is running fine now.

I have detail pictures for those who are interested :

1 . The board :

2 . detail of c806 location : ( yellow circle )

Size of c806 compared to small case screw :

4 . My awsome soldering skilzz ;-) , let's just say, it works...

Anyway, thanks for this post on this forum, it saved a nice monitor from the garbagebin.

regards,

Cabrioot

Thank you all for contributing to saving another monitor from the landfil. ( I was down to my last beat up 17" LCD )...

I used a Radio Shack 272-996 1uf 50v cap cost $1.88. I soldered the leads to the existing C806 Cap, only after final inspection w/ magnification could I see that in fact the original showed what appeared to be a hairline crack. I felt that further verified Jammtek's awesome diagnosis! I have spent about 3 hours total on this because of the work all of you did.

So to pay it fwd a bit... I noticed when I held the board up to the light, there are 2 holes perfecly spaced for my new cap to fit each leg through! So my new cap hangs out on the other side of the board where there is plenty of space with the leads going through to the other side wher I routed them to C806 and soldered... With practice this could look factory...

Thanks!! again

Marc

worked for me, went to radioshack and picked up a 5 pack of 470-Kohm 1/2 watt resistors and thanks to your post, i am now typing to you on the monitor that was broke.

Thank so much RICKY WI i have the same problem with my monitor, i just fix it adding the 500k ohms resistance (560k exactly) and has been working for 2 hours and counting! Thank u. I am mechatronic engineer and i was getting crazy with my multimeter and welder i change capacitors and nothing untill i found this post. Thank u once again and good luck guys with your stuff.

Add me to the list of happy monitor owners.I added the 500k resistor across c808 and monitor is working fine.

Thank you for the info and effort on your part!