HP L1702 goes on and off

[masik]

Re: HP L1702 goes on and off

I have also problem with my HP 1702 monitor, after I turn it on for the first time it will work for 30 seconds and then it will show black screen only. If I turn it off and then on again it will show picture for 2 seconds and then it will be black screen again. There is a black area on the circuit but I have no idea what to check and what I should replace.

[PlainBill]

Re: HP L1702 goes on and off

Set up a test. Set up the computer so it is displaying a screen that is mainly white, and disable the screen save and sleep mode. Turn off the monitor by pressing the power button. Leave this condition set up for a minimum of an hour, a day would be better. Now turn on the monitor. Does the screen have a pinkish tinge that disappears quickly? If it does, you have an aging CCFL. The only solution is to replace the CCFLs.

PlainBill

[amazinguk]

Re: HP L1702 goes on and off

I have also the same problem with my HP 1702 monitor. the same bord shown in the MASIKs picture. i have testet fuses -f801 f802 f803- -resistors--transistors--mosfet,s- they all in good condition- only not test it electrolyt capacitors look fine an flat to me. next thing i m gona open and chek the CCFLs bulb, and i will post again,

[amazinguk]

Re: HP L1702 goes on and off

amazinguk;232038]I have also the same problem with my HP 1702 monitor. the same bord shown in the MASIKs picture. i have testet fuses -f801 f802 f803- -resistors--transistors--mosfet,s- they all in good condition- only not test it electrolyt capacitors look fine an flat to me. next thing i m gona open and chek the CCFLs bulb, and i will post again




After every rain appears a RAINBOW

[budm]

Re: HP L1702 goes on and off

You can try this: https://www.badcaps.net/forum/showthread.php?t=19987

[amazinguk]

Re: HP L1702 goes on and off

the ccfl bulbs look like this; is not any good quality picture, but i think they can show something.. so one of them is black in the end, is that mean a fault.. thnx

[retiredcaps]

Re: HP L1702 goes on and off

so one of them is black in the end, is that mean a fault.. thnx

Possibly. Or it could be bad wiring. See budm's album at

http://s807.photobucket.com/albums/y...klight%20lamp/

[budm]

Re: HP L1702 goes on and off

You can plug the lamps back into the inverter board sockets, you can leave the ribbon cable from the LCD panel to the logic board out. power up the unit (pc should be hooked up to the monitor) and watch to see if all the lamps come on. yOu may may have bad wires on the end of the lamp assemblies also, but let see the result of observing the lamps on condition first since you already have the lamps out.

[selldoor]

Re: HP L1702 goes on and off

Did you test the inverter transformers t101/t102? With the power off -(for 5 minutes) and meter on 2000 ohms scale, check the resistance between pins 7 and 10 on each transformer and post the difference. If we move from the lamps to looking at the board we will need good clear pictures of both sides of your board.

[amazinguk]

Re: HP L1702 goes on and off

i will try secondary windings of a transformer pin 7--10. like you say. 4, 5 min and i will post the results,

[amazinguk]

Re: HP L1702 goes on and off

advice from selldoor, i"ve test the inverter transformers t101 & t102 in 2kohm with multimeter and they are .460 ohm, resistance, i have some picture of them not so clear but i think u can see something, i testet the CCFLs outside of display they light for second and go off, soo they are two sokets with pair lamps, one of them is pink and the other is a litl dark they are not so lighty,, one in each is OK, do they need to be pair ok to stay on what is your advice goood people???

[retiredcaps]

Re: HP L1702 goes on and off

one of them is pink

Pink is a sign that the ccfls are dying. As they die, they draw more power causing the pwm inverter IC to go into protection mode and shut down all the ccfls.

[amazinguk]

Re: HP L1702 goes on and off

thnx 4 induction: i will change them and post again,

[amazinguk]

Re: HP L1702 goes on and off

i changet the 2 of 4 ccfl,s and is working perfect now, in my monitor was only the 2 ccfl bad, thats all, it was a bit headaches during soldering them but finally got a fix. i had really really nice and clear suggestions from you guys, WHAT CAN I SAY only god bless you, thnx a lot,

[selldoor]

Re: HP L1702 goes on and off

Well done - its great to hear you got it fixed.

[alkuentrus]

Re: HP L1702 goes on and off

thanks for all the help.the moniter is working like a charm
i followed the your suggustions. i replaced the capititors and the back light.
heres a picture on what i changed.

Hello. I know there's is a while now... but did you replace the capacitors at both motherboards? I mean, power suply board and the other, the smaller one?

Regards

[selldoor]

Re: HP L1702 goes on and off

Hello. I know there's is a while now... but did you replace the capacitors at both motherboards? I mean, power suply board and the other, the smaller one?

Regards

In post 13 it shows what he replaced - do you need some help?

[alkuentrus]

Re: HP L1702 goes on and off

Hello. I know there's is a while now... but did you replace the capacitors at both motherboards? I mean, power suply board and the other, the smaller one?

Regards

For what I see, I believe it's not from the power suply board... I was just trying to be sure, to buy the right ones ( I live in madeira island and have to import them)

[alkuentrus]

Re: HP L1702 goes on and off

In post 13 it shows what he replaced - do you need some help?

I just ordered them all for both boards

[alkuentrus]

Re: HP L1702 goes on and off

In post 13 it shows what he replaced - do you need some help?

hello... Replaced all capacitors, but the problem is still there... Stay on for 1 second, hangs por two... looping like this... Now its time to test the side lamps, right?