Fujitsu l22w-1 , 2 sec black

[ahmedsamir]

A Fujistu l22w-1 flickering and dimming for 2 sec then black screen , it has Samsung panel LTM220M1-L01 , with two upper and bottom ccfl tubes .

the images for the power board are attached, focused on the capacitors.

I think the capacitors are OK, as their shape is good. (I'll go replacing them after consulting you as you are the experts, after being certain they are the problem).

by disconnecting the upper ccfl tube and just connecting only the lower one, the screen turns on its light very good without the flickering and dimming issue, but just for two seconds only then off.

this very good lighting image only continues for 2 secs and then off again till on - off , or connect/disconnect signal.

the good ccfl tube which is not flashing and dimming works good on both ports of the tubes , while the other (bad tube) woks badly on both ports.

so one of the two ccfl needs to be changed, am I correct?

could the LCD works with only one tube instead of the original two tubes , without being black after two seconds?

Could an expert help me resolve this issue?
Thanks In Advance.

[budm]

Re: Fujitsu l22w-1 , 2 sec black

It will take only one bad lamp for the protection circuit to kick in, you can bypass the protection circuit but that will be very bad idea.

[ahmedsamir]

Re: Fujitsu l22w-1 , 2 sec black

then the capacitors doesn't need to be replaced?
as the problem is with the bad lamb , which need to be replaced?
Do you recommend replacing the two lambs , or only the bad one?

[R_J]

Re: Fujitsu l22w-1 , 2 sec black

If you are going to take the panel apart to replace one ccfl, replace both of them. The working one is just as old as the bad one and would likely fail anyway.

[budm]

Re: Fujitsu l22w-1 , 2 sec black

if you are going to take the panel apart to replace one ccfl, replace both of them. The working one is just as old as the bad one and would likely fail anyway.

+10

[ahmedsamir]

Re: Fujitsu l22w-1 , 2 sec black

It will take only one bad lamp for the protection circuit to kick in, you can bypass the protection circuit but that will be very bad idea.

How to bypass the protection circuit, and why it is a very bad idea?
Why the protection circuit turning off the lamb when connected alone?
Thanks for your cooperation ,

[budm]

Re: Fujitsu l22w-1 , 2 sec black

When you only have one lamp connected, or no lamp connected at all, the open lamp (or no lamp connected, or lamp will not conduct when firing Voltage is applied) detection will kick in since you do want to have high Voltage (1500 ~ 2000V) present when there is no load connected which will cause arcing.
1) You can defeat the 2-second timer circuit if you can get the P/N of the IC in the inverter circuit.
2) You can remove the inverter transformer for the bad lamp and fool the protection circuit that two bad lamps are still present.
The modification will have to be done after you figure out the circuit of the inverter circuit section, so right now we need the P/N of the IC (IC501???) in the inverter section to find the spc sheet to get the pinout of the IC. We also need the good clear straight shot of the whole bottom side of the board to be able to trace out the circuit.

[ahmedsamir]

Re: Fujitsu l22w-1 , 2 sec black

Thanks for your help,