Acer AL1916W monitor backlight turns on/off twice

[wixxwa]

Hello,

I'm new in this forums and this is my first post.

I have Acer AL1916W monitor that comes on/off twice(only backlight), led turns green and then orange. No Acer logo, just white screen. What can be wrong?

All caps looks good.

[jetadm123]

Re: Acer AL1916W monitor backlight turns on/off twice

If all you're getting is a white screen (a black screen would indicate the backlights are off), then that's an indication that the backlights are on and the problem may be in the panel electronics control board. I suggest you put the power supply back in and look at the back of the monitor in a dim room to verify that the backlights indeed remain off. If the backlights are on, the light will "bleed" through the back of metal chassis.

[wixxwa]

Re: Acer AL1916W monitor backlight turns on/off twice

Link to video i filmed right now. When backlight flashes two times, lcd goes to stand-by mode. Nothing more happens. I can turn off lcd and turn on, still the same problem.

[alexanna]

Re: Acer AL1916W monitor backlight turns on/off twice

I think you may have a problem with the panel.Try unplugging the LDVS from the panel and see how the PLED responds

[wixxwa]

Re: Acer AL1916W monitor backlight turns on/off twice

I think you may have a problem with the panel.Try unplugging the LDVS from the panel and see how the PLED responds

Tried to unplug mainboard from LCD, PLED and backlight responds same.. No changes.

[Rtech]

Re: Acer AL1916W monitor backlight turns on/off twice

On the right hand side of the Board is a connector,and writtn just above it is a Legend,indicating,what voltages should be,on each pin.You need to measure them using a meter measuring DC Volts.Do this with just the Power lead attached to the Board,and do NOT have the lead from that connectior plugged into the Logic Board.Then re-connect the logic Board and measure again,advising what readings you get in both cases.

[wixxwa]

Re: Acer AL1916W monitor backlight turns on/off twice

Legend Pluged Unpluged
1.VCC5v -- 5.12 -- 5.17
2.VCC5v -- 5.12 -- 5.17
3.GND
4.ON/OFF -- 0.04 -- 0.0 -- When monitor turning on there is 3.3v
5.Brightness -- 3.12 -- 0.0
6.GND
7.VOLUME -- 3.3 -- 0.0 -- (not used)
8.Audio MUTE -- 2.07 -- 0.0 -- (not used)

On mainboard there is two voltage regulators:
LD1117AL33 Pin3- 4.8v pin2-3.12 pin1- GND
AS1117L-18 Pin3- 3.18 pin2-1.78 pin1- GND

I have checked almost everything. Dont know where to look.. searched whole google, didnt find same problem like mine..

P.S. Sorry for my English..

[trebo]

Re: Acer AL1916W monitor backlight turns on/off twice

wixxwa
check the fuse on the t.con panel, a failed fuse will give you a white screen as well as no voltage to the panel

[wixxwa]

Re: Acer AL1916W monitor backlight turns on/off twice

wixxwa
check the fuse on the t.con panel, a failed fuse will give you a white screen as well as no voltage to the panel

Where i should look for fuse? in both PCB i see only one fuse, near AC socket.

I checked all VCC pins of mainboard IC, everything OK.

I found one fuse in LCD, but everything is OK with him.. Checked VCC to LCD- OK too..

[retiredcaps]

Re: Acer AL1916W monitor backlight turns on/off twice

On mainboard there is two voltage regulators:
LD1117AL33 Pin3- 4.8v pin2-3.12 pin1- GND
AS1117L-18 Pin3- 3.18 pin2-1.78 pin1- GND

The reading for LD1117AL33 is low. Pin 2 should 3.3V DC. You have 3.12V DC. That could be enough to throw off the entire circuit and causing the lcd to restart.

A voltage regulator should be +/- 1%. So a 3.3V DC regulator should be

3.3 x 1.01 = 3.333
3.3 x 0.99 = 3.267

3.12 is off by more than 5%

If you have any junk boards (like an old PCI card), you can find these regulators quite easily as they are common parts. Otherwise, they are fairly inexpensive parts brand new.

[wixxwa]

Re: Acer AL1916W monitor backlight turns on/off twice

I measured again LD1117AL33 and it has 3.28v, i think i made mistake, sorry for that.

All in all i think LCD panel is bad. But i dont have how to check it..
-----------------------------------------------------------------------------
Finally found the problem: connection between panel and mainboard was bad. cleaned contacts with concentrated vodka and bit pushed harded and it works. now everything OK.

Thanks a lot for help.

[retiredcaps]

Re: Acer AL1916W monitor backlight turns on/off twice

Where i should look for fuse?

From the logic card, there is a connector that usually goes to a board at the top of the lcd. This board is underneath a metal shield. There may be a smd fuse on this board.

[PlainBill]

Re: Acer AL1916W monitor backlight turns on/off twice

I measured again LD1117AL33 and it has 3.28v, i think i made mistake, sorry for that.

All in all i think LCD panel is bad. But i dont have how to check it..
-----------------------------------------------------------------------------
Finally found the problem: connection between panel and mainboard was bad. cleaned contacts with concentrated vodka and bit pushed harded and it works. now everything OK.

Thanks a lot for help.

Just one more reason to keep a bottle of vodka around.

PlainBill