ASUS LCD monitor repair

[Taran'li Maren]

I have a broken ASUS VW224 monitor which I am attempting to repair (it is just over 3 years old, so out of warranty, but not obsolete). However, I have been unsuccessful so far. I have not repaired electronics before, and lack most of the fundamentals of how they work. I would appreciate any advice that anyone is willing to provide.

The symptoms are two-fold.

First, after turning the power on, it displays what it is supposed to for half a second or so and then the backlight goes out. Using a flashlight, I am able to see a shadow of what is supposed to display. The power light stays on blue. Occasionally, it stays on for longer (a minute or two). When it does, the brightness of the screen flickers.

Second, in the weeks up to its failure, there was some video distortion, and sometimes it can still be seen in the half second that it is on. The distortion consists of a noisy line down the center of the screen, and some horizontal noise (it sort of looks like some pixels are shifted to the right by a random amount).

None of the original capacitors were bulging in the slightest. There was no sign of scorch marks or damage either.

After researching this, I replaced 7 of the 8 electrolytic capacitors on the power board anyway. I have attached images of the power board, with the new capacitors marked in red and the remaining original capacitor marked in blue (120uF, 450V). The new capacitors are all Rubycon YXG series with the same specs as the original (uF and V). I did not replace the largest capacitor because I couldn't read the rating at the time, as it is glued to the board.

https://zhentarim.net/images/20141120_asus-vw224-power-board-front.jpg
https://zhentarim.net/images/20141120_asus-vw224-power-board-back.jpg

 

[PottedMeat]

First, after turning the power on, it displays what it is supposed to for half a second or so and then the backlight goes out.

if the capacitors are all fine i would take out the 4 ccfl tubes. carefully push back the rubber boots and check the connections. i had a monitor where the picture would go out after a few seconds. the soldered connections to the ccfls were severed, resoldering them solved the problem.

when you take out the ccfls make sure you are working in a clean area, any dust that gets between the diffuser layers will show up as a shadow.

 

[Taran'li Maren]

Ah, I'll have to figure out how to open that part up. Thanks.

 

[inachu]

Yeah buy a magnifying glass and see if the solder is truly broken.

 

[silicon]

I have a broken ASUS VW224 monitor which I am attempting to repair (it is just over 3 years old, so out of warranty, but not obsolete). However, I have been unsuccessful so far. I have not repaired electronics before, and lack most of the fundamentals of how they work. I would appreciate any advice that anyone is willing to provide.

The symptoms are two-fold.

First, after turning the power on, it displays what it is supposed to for half a second or so and then the backlight goes out. Using a flashlight, I am able to see a shadow of what is supposed to display. The power light stays on blue. Occasionally, it stays on for longer (a minute or two). When it does, the brightness of the screen flickers.

Second, in the weeks up to its failure, there was some video distortion, and sometimes it can still be seen in the half second that it is on. The distortion consists of a noisy line down the center of the screen, and some horizontal noise (it sort of looks like some pixels are shifted to the right by a random amount).

None of the original capacitors were bulging in the slightest. There was no sign of scorch marks or damage either.

After researching this, I replaced 7 of the 8 electrolytic capacitors on the power board anyway. I have attached images of the power board, with the new capacitors marked in red and the remaining original capacitor marked in blue (120uF, 450V). The new capacitors are all Rubycon YXG series with the same specs as the original (uF and V). I did not replace the largest capacitor because I couldn't read the rating at the time, as it is glued to the board.

https://zhentarim.net/images/20141120_asus-vw224-power-board-front.jpg
https://zhentarim.net/images/20141120_asus-vw224-power-board-back.jpg

not trying to throw water on your hopes to repair this monitor but these things are made sometimes to not come apart easily. You might be better off to buy a new one.

 

[PottedMeat]

not trying to throw water on your hopes to repair this monitor but these things are made sometimes to not come apart easily. You might be better off to buy a new one.

the hardest part in my experience is opening the enclosure. everything else is held in place with a couple screws or tabs that easily detatch (the display itself). he just has to stay clean (watch for dust/dandruff/hair) and keep track of part orientation.

 

[Taran'li Maren]

I actually already purchased a replacement, but I wanted to try and repair it anyways, for learning.

I was unable to access the tubes yesterday, however overnight I had a realization that they are probably accessed from the front (by removing the diffuser) instead of the back. I will make another attempt tonight.

While I was trying last night though, one of the eight wires connecting the power board to the LCD (probably to the backlight, but I'm not sure) fell right out. It looks a little corroded, and was evidently not attached securely to its plug. I was being very gentle, so I don't think I was too forceful. It goes into a foam cube in the very corner of the panel, which is covered by the back plate which I was unable to remove last night.

 

[bryanl]

Black corrosion is common on silver plated contacts and isn't as bad as it looks. Reseating the connectors is safe, but don't sand them.

Solder failures can be nearly microscopic, and some techs resolder almost everything, especially the leads of components that run hot or that receive high mechanical stress, such as connectors and heavy pieces like transformers and coils. Some techs resolder all transformer and coil leads routinely.

 

[Matt1970]

if the capacitors are all fine i would take out the 4 ccfl tubes. carefully push back the rubber boots and check the connections. i had a monitor where the picture would go out after a few seconds. the soldered connections to the ccfls were severed, resoldering them solved the problem.

when you take out the ccfls make sure you are working in a clean area, any dust that gets between the diffuser layers will show up as a shadow.

It's either that or the inverter circuit itself.

 

[Taran'li Maren]

Here is an update. I'm taking it slow, so bear with me.

I accessed the CCLFs, and it turned out that both wires in that corner had broken off inside the rubber boot. The boot itself is cracked and has crunchy bits stuck inside it. I haven't yet checked the other three corners, for fear of breaking the connections. I may resolder all 8 connections, just in case.

When I resolder the broken connections, would it be a problem to use electrical tape instead of trying to reuse the damaged boot?

 

[PottedMeat]

Here is an update. I'm taking it slow, so bear with me.

I accessed the CCLFs, and it turned out that both wires in that corner had broken off inside the rubber boot. The boot itself is cracked and has crunchy bits stuck inside it. I haven't yet checked the other three corners, for fear of breaking the connections. I may resolder all 8 connections, just in case.

When I resolder the broken connections, would it be a problem to use electrical tape instead of trying to reuse the damaged boot?

the boot keeps the spacing correct between the tubes and also functions as the mount on the ends - i would try to keep as much of it as possible.

(i've never had to replace them - dunno what they're called alone)

 

[silicon]

Here is an update. I'm taking it slow, so bear with me.

I accessed the CCLFs, and it turned out that both wires in that corner had broken off inside the rubber boot. The boot itself is cracked and has crunchy bits stuck inside it. I haven't yet checked the other three corners, for fear of breaking the connections. I may resolder all 8 connections, just in case.

When I resolder the broken connections, would it be a problem to use electrical tape instead of trying to reuse the damaged boot?

I would avoid using electrical tape since it will probably degrade quite quickly. Try to find some heat shrink tubing of adequate size since this is a little lore resistant.

 

[Matt1970]

I would avoid using electrical tape since it will probably degrade quite quickly. Try to find some heat shrink tubing of adequate size since this is a little lore resistant.

Shrink tubing would be best. Those CCFL's are high voltage so they need to be insulted well.

 

[Taran'li Maren]

I know it has been a while, but I am here to report a partial success. I resoldered the bad CCFL joints and managed to reassemble it. The monitor is functioning now, for the most part. I am using it to type this message.

I did end up purchasing and using the shrink tubing that silicon and Matt1970 suggested. Those are fun to use, and much more professional looking than tape.

Unfortunately, the monitor is not 100%. I think I put the diffusers in wrong, because I see a light hex pattern on all the light surfaces. I should have kept better notes, or taken more pictures.

More importantly, a vertical blue line of stuck pixels appeared a couple of minutes after I turned it on. I may have damaged something while working on it. Perhaps the ribbon cable?

In any case, thanks to all of you for the help and advice.

 

[James Galyon]

if the capacitors are all fine i would take out the 4 ccfl tubes. carefully push back the rubber boots and check the connections. i had a monitor where the picture would go out after a few seconds. the soldered connections to the ccfls were severed, resoldering them solved the problem.

when you take out the ccfls make sure you are working in a clean area, any dust that gets between the diffuser layers will show up as a shadow.

We are currently poor to the point of occasionally running out of food and buying insulin on Craigslist to keep my wife alive. My computer is my only link to the outside world since I stay home 24/7 to care for my wife, so I attempt to fix everything my self. My ASUS VW246H LCD monitor went out a few months ago and my eyes are nearly too bad to see my old 17" CRT which I now use to write to you. I learned through You Tube that caps go bad on the boards and I found 4 swollen caps on the board in my monitor. I replaced all the caps on both boards with new ones, but still had the exact same problem. When I power on the monitor, one second later the ASUS logo displays for 1 second and disappears. Then at the 7 second mark the screen turns on with what ever image is currently running on my computer, usually my desktop. One second later the image disappears again and nothing more shows unless I turn off the monitor power and turn it back on at which time the exact same series occurs. I ended up finding another ASUS monitor with a cracked screen, but identical boards that still worked. I changed them out but still have the exact same problem with my display going on and off.

I saw your mention of the "4 ccfl tubes".

Can you tell me where these are located?

Are the ccfl tubes delicate like halogen lamps that will bubble up and burn out if the oil from you hand gets on them?

What should ccfl be cleaned with?

Can you direct me to any further instructions on re-soldering them?

Also what type of solder should I use and what wattage solder iron?

All my solder is 10 years or older. Does solder go bad?

I have repaired boards years ago and did a clean job of it, but nothing seems to want to stick well to the board. Any information would be greatly appreciated. Thank you. God bless. James Galyon

 

[PhIlLy ChEeSe]

We are currently poor to the point of occasionally running out of food and buying insulin on Craigslist to keep my wife alive. My computer is my only link to the outside world since I stay home 24/7 to care for my wife, so I attempt to fix everything my self. My ASUS VW246H LCD monitor went out a few months ago and my eyes are nearly too bad to see my old 17" CRT which I now use to write to you. I learned through You Tube that caps go bad on the boards and I found 4 swollen caps on the board in my monitor. I replaced all the caps on both boards with new ones, but still had the exact same problem. When I power on the monitor, one second later the ASUS logo displays for 1 second and disappears. Then at the 7 second mark the screen turns on with what ever image is currently running on my computer, usually my desktop. One second later the image disappears again and nothing more shows unless I turn off the monitor power and turn it back on at which time the exact same series occurs. I ended up finding another ASUS monitor with a cracked screen, but identical boards that still worked. I changed them out but still have the exact same problem with my display going on and off.

I saw your mention of the "4 ccfl tubes".

Can you tell me where these are located?

Are the ccfl tubes delicate like halogen lamps that will bubble up and burn out if the oil from you hand gets on them?

What should ccfl be cleaned with?

Can you direct me to any further instructions on re-soldering them?

Also what type of solder should I use and what wattage solder iron?

All my solder is 10 years or older. Does solder go bad?

I have repaired boards years ago and did a clean job of it, but nothing seems to want to stick well to the board. Any information would be greatly appreciated. Thank you. God bless. James Galyon

James
Welcome!
If the CCFL'S are to the point of needing to be cleaned, only suggestion would be to use air and try to blow out all contaminants. Yes do not touch them, no oil from your hands either.
Usually the inverters go bad, you can google how to trouble shoot them. The CCFL'S are in the screen, and it is suggested to keep it all as clean as possible(clean room) make sure dust and the likes does not enter it.
on a display these can be broken, from the monitor falling or being hit/impacted. The lines that connect the CCFL'S can be soldered, I would use low voltage as they are so small. Solder works best when the iron is clean but also has some tin on it, also you use flux to make solder flow.
Old solder should be good, I am a member at a forum who can probably help you in more detail at "BADCAPS.COM"(they don't like links off the site).

Good Luck!
PS for best results and more help, start a new thread. List your model number, and HOW or what happened to the unit(IE old age,etc). Give as much info as possible to make helping you easier, or makes it easier to trouble shoot. on most bad displays that are older the inverter boards go bad like in the OP(original posters picture's) you can see the PCB is yellowed near where is says caution high voltage(where the CCFL"S plug in) those 2 little inverters are shoot and need replacing. The rest of it is a power supply, the caps look fine(but can be tested). I would test other things like the diodes, etc.
@OP
Crunchy and CCFL'S bad news.........

 

[PottedMeat]

Can you tell me where these are located?

Are the ccfl tubes delicate like halogen lamps that will bubble up and burn out if the oil from you hand gets on them?

What should ccfl be cleaned with?

Can you direct me to any further instructions on re-soldering them?

Also what type of solder should I use and what wattage solder iron?

All my solder is 10 years or older. Does solder go bad?

the operation is very similar to this: http://www.laptoprepair101.com/replace-laptop-backlight-ccfl-lamp/

ccfl LCDs are generally have the ccfl lamps on the top and bottom of the screen assembly. if you're lucky the lamps can be slid out, if not you're going to have to take the screen itself apart. as previous posters have said - keep everything clean. anything that you get in between the screen and the various polarizers will show up as an annoying shadow. i would just use plain old leaded electronics solder. and it doesn't go bad.