"Rajiv Mehra" wrote in message
...
Hi everyone,
I have a LCD monitor, a QVision 15 inch touchscreen. The model is J5PX.
It's backlight has some problem. I would appreciate if anyone could please
help me out here.

Symptoms:
On power on the screen flashes on for half a second and then it goes
blank.
Also if I give it video signal it also flashes once.

I opened it up and used a flashlight to shine through the back, the
display
is OK. Even during the 1/2 second turn on, the display appears just fine.

The monitor has two backlights, one at the top and one at the bottom. Both
the backlights' reflectors have two CCFLs. the bottom one is the one
which
flashes on. The top one does not light up, but it's one end does glow for
a
second. It appears that the bottom CCFL is the one that used to be lit up
all the time (while the monitor was working properly). I can see that the
bottom CCFLs have their ends blackened a little bit. The top CCFLs do not
have black ends.

Of course, I have tried swapping the top and the bottom ones (the
connectors
are the same), but the same things happens. The bottom CCFL just flashes
on
for half a second and then ...nothing.

From all this it appears that either the inverter is bad or the driving
circuitry has gone bad.

About the inverter:
The inverter has 4 wires going to it from the "motherboard" of the LCD
monitor. Two are just GND. One is +5v DC while the monitor has a video
signal supplied to it. The 4th seems to be 'floating'.

I did some search on UseNet and found some tips. People are saying that
the
tiny fuses burn out. In my case there is only one fusible resistor and
that
is not open.

Questions:

Has anyone encountered and solved the same problem?
What is the possibility of having the inverter faulty? How can I test it
out
?
The inverter is being given some signal which controls the brightness. I
suspect that circuit might be faulty. How to test that ?

Inverters specs:
Inverter part numbers: CDA-004A
Manufacturer:- CHI-SAM

There are some numbers on the track side too
F27003004A
HK100002
CHI 0110
E



If the inverter pinout is that simple you may be able to just replace them
with cheap surplus inverters. All Electronics had some last I checked, could
be the tubes are worn out as well and will no longer reliably run from the
output of the inverter.