Proview pl926wbi on for 2 sec and LCD turns off

[paziu]

Hello, I got this monitor hoping for an easy fix, well, it is not that easy ( for me ... ) - beside the fact that this is a very >cheap< made device, and its guts look like after a cat5 hurricane, I managed to replace 2 bad caps on the power supply and the inverter... there was a cold solder joint also on a 220uF..
it has 2 circuits x 2 CCFLs outputs ( for top and bottom ) - tested the outputs with a spare CCFL set i got, both TOP outputs are good, both BOTTOM are DIM ( 25% lit ) - the LCD have all 4 CCFLs good. The top and bottom circuit powers off with either 4, 2 or no CCFLs connected, the voltages on the power supply, and going to the VGA board look good and stable. there is two transformers, for top and bottom, two coils - black squares, and nothing that looks suspicious the voltages are same on both circuits ( difficult to measure since it cuts off quickly, after 2 sec of "good" display - and no, it does not go into suspend ) I am basically running out of ideas...

Thank you for any suggestions!

paziulek

[FIXITNOW]

Re: Proview pl926wbi on for 2 sec and LCD turns off

last one ihad i replaced 4 x 470uf Capcitors dead and 1 220uf Capcitor dead
if no better check the ams1117 regulator. is outputting a 3.3v.

[PlainBill]

Re: Proview pl926wbi on for 2 sec and LCD turns off

Hello, I got this monitor hoping for an easy fix, well, it is not that easy ( for me ... ) - beside the fact that this is a very >cheap< made device, and its guts look like after a cat5 hurricane, I managed to replace 2 bad caps on the power supply and the inverter... there was a cold solder joint also on a 220uF..
it has 2 circuits x 2 CCFLs outputs ( for top and bottom ) - tested the outputs with a spare CCFL set i got, both TOP outputs are good, both BOTTOM are DIM ( 25% lit ) - the LCD have all 4 CCFLs good. The top and bottom circuit powers off with either 4, 2 or no CCFLs connected, the voltages on the power supply, and going to the VGA board look good and stable. there is two transformers, for top and bottom, two coils - black squares, and nothing that looks suspicious the voltages are same on both circuits ( difficult to measure since it cuts off quickly, after 2 sec of "good" display - and no, it does not go into suspend ) I am basically running out of ideas...

Thank you for any suggestions!

paziulek

Bad transformer in the inverter (82% probablility).

PlainBill

[paziu]

Re: Proview pl926wbi on for 2 sec and LCD turns off

Thank you very much for the reply,
I will check the regulator - if there is 2, one for top CCFLs and another for the bottom, than this could be the reason... From what I see, there is 2 independent transformers, and I also will check for the part# availability, as soon as I have any results I will let you know, thanks again!

[paziu]

Re: Proview pl926wbi on for 2 sec and LCD turns off

before doing anything that involves spending a few dollars, and waiting another week, I decided to swap the transformers on the board - PlainBill - the 82% probability became 100% fact, one of the transformers is shot, now the top CCFLs are dim - bottom became bright... THANKS!
now I need to find a decent price, $20 for the part is still too high... I could get an another wide screen "patient" for this price.
What I also tried, is removing the bad transformer and connecting the CCFLs to just the GOOD circuit - the picture is quite bright, but it still cuts off after 2 sec.. so I am guessing the circuit cuts off if there is too much or too little current... I do not know, just a guess.. for sure it is not within the "norm" - is it possible I got an another bad part there or is it known, that the protection will disconnect the circuit if "one of two transformers is missing" ?

Thank you again! I will hunt now for the transformer or an another BAD Proview...

paziu