Acer AL1717A

[ehrja]

Acer AL1717A

This monitor was working great, it was working continually 8hrs at the office but now is having troubles the problem seems to be the back light.

I do a control test and notice that when I turn on the monitor it does well but at the minute it seems to shutdown I also notice that the status leed still on and green. Using a torch lamp I can see the windows environment and I thought that it can be a bad cap, to be easy and because in that moment I don't have my cap ESR meter I change all the caps because they looks flat, no evidence of physical bad caps.

I do the repair an test it with the same anomaly.
I thought it could be a could join soldering and reheat almost all trohole joins, the testing throw the same results.

What could be happening here, any idea?

[Dumah Brazorf]

Re: Acer AL1717A

It could be the inverter trasformer for the lamps or the lamps themself.
Do you have any spare lamp to test the inverter?

[ehrja]

Re: Acer AL1717A

Yes I do have one spread, I'll test one by one and check what is going on, I also have a cfl lamp tester I'll chech the lamps in the lcd also.

[ehrja]

Re: Acer AL1717A

Hello I test already the 4 lamps in the monitor they are in groups of 2 wraped with shrink tube. 3 of them toun on White light, just one is blinking red dark color like a mini storm, is obvious that this one is damaged and I wonder if is possible to use only 3 of them and just leave the bad one disconnected?
Could that damage other components like the inverter or the other lamp that is aside the bad one?

[mikey5791]

Re: Acer AL1717A

Hi ehrja,

I have experienced using two lamps out of four lamps in a Dell LCD monitor due to
only having two lamps connector on a different version power board replacing a bad
power board. The bad power board has four lamps connector.

Surprisingly the new power board works but at a slightly dimmer
screen which is still usable by adjusting the screen brightness to maximum.
BTW, I am still using this monitor for the past three months with no issue whatsoever.

[budm]

Re: Acer AL1717A

Hello I test already the 4 lamps in the monitor they are in groups of 2 wraped with shrink tube. 3 of them turn on White light, just one is blinking red dark color like a mini storm, is obvious that this one is damaged and I wonder if is possible to use only 3 of them and just leave the bad one disconnected?
Could that damage other components like the inverter or the other lamp that is aside the bad one?

It depends on the protection circuit design, most will shutdown the inverter circuit if one of the lamp is not detected in the first 3 second when the startup Voltage is applied to the lamp but the lamp fails to conduct or not present, it is done that way so you will not have high Voltage sitting there without the load so it arcs over.

[ehrja]

Re: Acer AL1717A

OK I got it, actualy I remember a tutorial to bypass the security circuit adding tree big resistors in series to dummy load the lamp I do not remember the details.

Fortunately I got an old monitor that is also bad but the LCD was ok same brand and size and also is compatible with the lamps and the video buss so I just change it, the monitor was working fine for about 30 minutes or so, actually the quality of the image was better, tomorrow I'll test it again a few hours.
and post a picture