benq gl2450 no power

[gasinmars]

i have a problem with this screen , when i plug it to the elecricity it doesnt turn on and the orange light beside the power button "turns on" all the time .
bytheway i opened the screen and didnt see any blown caps but in the logic board the main chip is so hot .............

could some one help me ?

[gasinmars]

Re: benq gl2450 no power

any helppppppppppppppp

[ReeceyBurger123]

Re: benq gl2450 no power

What voltage readings do you get ?

[viziks]

Re: benq gl2450 no power

In the component view of Powerboard the bottom right corner is scorched below which is a smd Mosfet.Check that for shorts and voltage on all 3 legs.
When you press power switch does orange light switch off ?
Seems the smd mosfet and or 16pin chip below it could be defective.These components feed the LED backlight of the panel.

[gasinmars]

Re: benq gl2450 no power

yeah still orange color when i press it.
so how could i messure the voltage of the 3 pins and what each pins should display in voltages ?

[budm]

Re: benq gl2450 no power

Did you check the capacitance and the ESR of those 4 caps to the right of the main yellow power transformer? if those caps are bad, it can cause over heat problem.
Bad caps can look normal.
Also check the rectifier diode (I cannot read the designator of the Diode) that feeds the DC to those caps for the LED BACKLIGHTS Voltage booster circuit.

[gasinmars]

Re: benq gl2450 no power

zoom in to the mosfet you will see that i wrote the voltages in the right side

[gasinmars]

Re: benq gl2450 no power

here is the voltages

[gasinmars]

Re: benq gl2450 no power

anyone could help me?

[konecma]

Re: benq gl2450 no power

Hello,
same problem, LCD in standby, voltage ok
Motherboard fail

[rddube]

Re: benq gl2450 no power

You might want to read this thread, it's the large chip on the mainboard that is probably shorted.

https://www.badcaps.net/forum/showthread.php?t=67285

If you want to confirm it, check the resistance on the mosfet I circled in the photo which is 3.3v in and 1.8V out...i was getting approx. 80 ohms. I replaced that big chip twice to find out that it was the mosfet on the power board providing the 5 volts to the mainboard that was the problem. After I changed that mosfet on the power board AND the big TSUM chip, monitor came back to life....I also installed a small video card fan inside the monitor as it has a tendency to heat up.

If confirmed, you can either get a new board but change the mosfet on the power board first.

In my tinkering, I came across a board that had the same board number as mine but different monitor model number but I bought it. I arrived after I had fixed the monitor but the monitor was still open so I tried it and lo and behold, it worked! Didn't need it anymore, so I put it up for sale on Ebay http://www.ebay.ca/itm/202291559401?...84.m1558.l2649

[rddube]

Re: benq gl2450 no power

Sorry, in my previous post:

on the power board providing the 5 volts to the mainboard

should have read

on the power board providing the 3.3V to the mainboard.