One more thing:
I just read that the inverter needs 12 volts input. none of those three
wires have a 12 volt input on them.
The +5v is just a "tuen on display" signal.
BUT then again ....if there is no 12 v input then how does the light flash
on for a second??
Any input ???
---------------------------------------------------
"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
A Google search brought me to this page. The second inverter from the top
(the 15" model) looks very similar to mine.
http://www.chisam.com.tw/p6-1.htm
Any tips / suggestions in solving this problem would be highly
appreciated.
Thanks
Rajiv
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