Want to Join my Adventure ?? in repairing a LCD monitor

[JBH]

Really newbie. Adventure to repair 2 LCD Monitor CMV model A150X2 T03.

Current tool, only a screw and soon a multimeter.

Premorbid : well functioning.

Cause of malfunctioning : my current thought is a wrong adapter was
used. This monitor, at the back, labeled the electrity requirement as
12V DC 2.7 A. Another adapter was used which rated the output being
12-24 V DC , 35 W.

Symptoms: firstly, the monitor takes long time to work. It has some
back light but no display. All people were thinking it is the computer
going slow. Now I think it is the LCD problem. After around 10 mins, it
works as usual. So that's why all is thinking computer problem, booting
very slow.

After few days, it has no more display but still some backlight.

I have never prior experience in repairing things. But as I may have my
mid-life changes (other people thinks it is crisis but I think it is
time I have to experience thing as I start to learn piano and repair
electronics which I love a lot but never really enjoy)

I opened the chasis without much problems. I saw 2 PCB, one larger, and
one smaller. I think the smaller is the inverterd board (read from
other news). I saw one fuse I guess it is. on the board it labels as F1
and with I saw a 3A on that piece.

My first questions, is dangerous to conncet to the normal adapter now
to check things? Does the inverter board convert back DC to AC ?

Waiting for you hobbyist to join my adventure.

Can I post the picture here ??

JBH-HK

 

[Jixter]

Hi another few ideas for you. Hope this helps also.

It sounds like you have a poor computer, and it goes to sleep after a period
of time.
Do you have a light inside your computer? Sometimes a ballast such as you
would get with a fluorescent bulb interferes with the Video card inside
computers.. Remove it.

Get a monitor that works and hook it up to your computer.
Boot the computer so that you are in the computer's bios screen
This is not windows but the early boot menu only.

With that you can troubleshoot if it is your LCD or computer.

If you computer is sending a signal that is improper for the LCD it may not
show an image.
For example if you send the LCD a resolution that it cannot handle it may
not display
If you send it a refreshrate that the LCD cannot handle it may not display.
If you have the wrong driver it may not display
If you have a poor monitor cable it may not display
If the cable has a bent or missing pin it may not display

etc..

Alternatively you should also try the monitor on another computer besides
the one your are testing with.
Before hooking up the LCD you should choose a resolution common to most/all
LCD monitors.
800x600 60hz would be my first choice.

 

[Jixter]

My first questions, is dangerous to connect to the normal adapter now to
I don't think it can get worse... Remember high voltage from inverter EVEN
WHEN UNPLUGGED.

I think so yes.. I think the bulbs require high voltage alternating current.

 

[JBH]

Hi Jixter, thanks for coming again. I have changed computer and cable,
the problem is the same. So I diagnose it a LCD problem.

I went out to buy a multimeter during lunch hour. I checked the two
fuses that I could find on the board one of which should be the
inverter where I see a big transfomer coil and caution High Voltage. I
tested the fuse and it is close.

The other PCB fuse F2 is also close. So the hope that I could find an
open fuse and replace is not workable.

I just come up with a funny idea, if I connect the LCD monitor and
keep it turned on with the computer, do you think any chance the LCD
will start to work again. ? I haear somebody saying the for low current
device. this works sometimes. But I don't think the LCD is really a low
current device.

I will call the monitor I am working so far is the small Monitor 1. Now
I leave the small monitor 1 on with the computer and see,.

Now come to the 2nd bigger Monitor 2. Well this monitor do not have any
back light at all when swithced on. I am hoping this is due to only a
open fuse. I will venture to oopen the chasiss and see how it goes.

The mere fact that I can open the chassis and reassemble it back nicely
already make me feel a bit satified. Ha ha....

Shall keep you post on the progress. I think I better make a BLOG, any
idea I can get a free website to host a Blog ? And I can take the
pictures all along.

JBH-HK

 

[Ancient_Hacker]

If the monitor ever works at all, it's not the fuse. fuses once they
fail stay failed.

First make sure you're using the right AC adapter. It must supply the
SAME voltage as the panel needs, and at the same or more current. No
exceptions.

The most common cause of startup problems is worn out fluorescent tubes
(called CCFL tubes). How old are these monitors? If they've been ON
for more than a year or two, that's probably the problem.
Unfortunately replacing the tubes costs a LOT of money at a service
shop. If you try to do it yourself, it costs a lot less BUT unless you
are a skilled swiss watchmaker you're likely to break the tubes
(they're just 2mm in diameter and as long as the display). Don't even
think of doing this unless you're extremely skilled at electronic
repair!

 

[JBH]

For those who follows: Monitor 1 have intact fuses. It works perfectly
fine until after using the wrong adapter. Now it is keep on running
with a correct adapter and computer running. One interesting
observation that there seems coming back of functions. By that I mean,
Monitor 1 only has the back light on. After keeping it on a while,
there is some response to the monitor control key, eg menu key,
brightness adjustment key. Before, nothing happens when I press these
keys. After few hours running, when I increase the brightness, the back
light increase the brighness, though still no other images. See how
tomorrow goes.

For bigger monitor 2, when I turned it on, there is even no backlight,
this again make me feel whther the fuese are gone. Only the power
swtich LED light working. But not yet able to open the chassis
smoothly. Will try again tomorrow morning.

Cheers
JBH-HK

 

[Jumpster Jiver]

For those who follows: Monitor 1 have intact fuses. It works perfectly
fine until after using the wrong adapter. Now it is keep on running
with a correct adapter and computer running. One interesting
observation that there seems coming back of functions. By that I mean,
Monitor 1 only has the back light on. After keeping it on a while,
there is some response to the monitor control key, eg menu key,
brightness adjustment key. Before, nothing happens when I press these
keys. After few hours running, when I increase the brightness, the back
light increase the brighness, though still no other images. See how
tomorrow goes.

For bigger monitor 2, when I turned it on, there is even no backlight,
this again make me feel whther the fuese are gone. Only the power
swtich LED light working. But not yet able to open the chassis
smoothly. Will try again tomorrow morning.

Cheers
JBH-HK

For monitor 1: It sounds like the power supply INSIDE THE MONITOR,
after the external adapter, may be damaged. Maybe the different
voltages necessary to run the monitor are slowly coming up one at a time.

Monitor 2: If you shine a light at the screen at different angles and
see a picture, then the backlights are out. Usually replacing the fuse
alone is not a cure, You probably need to change the electrolytic
capacitors on the inverter board first.

Good luck. You can't learn without trying. BUT BE CAREFUL. The CCFL
tubes and the LCD panel are very fragile and will break easily if
mishandled while they are removed from their mounting points.

 

[JBH]

Dear Jumpster, thanks for joining in. My both monitors are in my office
and I am having my 2 weeks vacation. Will update you the progress when
I start resuming the work.

JBH-HK

 

[JBH]

Dear all,

It is time to finish. When I am having the holiday, my staff took the
two monitors for repair and he paid the bill.

Adventure terminated.

Thanks

JBH-HK