Problem with Acer AL1715 Monitor

[SilverArcher]

Hi all,

I have a problem with a LCD monitor that I recapped today(as per images), but before I start I will mention what happened to the Lcd before the recapping:

When the Lcd was turned on it displayed the Acer logo but very faint, then after 2 seconds or so it when dark, the green led remained on.

Read some posts on this forum they mentioned that when this happens there are some bad caps on the inverter board.

So I managed to replace the following 6 caps (as per images):

2 x 470uF 16v
2 x 1000uF 16v
2 x 150uF 50v

Now the the Lcd´s green led falshes and does not turn on at all.

Checked the fuse, measures at 0.4 ohms.

Any ideas?

[Rtech]

Re: Problem with Acer AL1715 Monitor

I Would recheck all the soldering on the caps you have replaced .I would also check that plugs etc have been refitted firmly.The photos are also very dark,and they need to be updated,as a quick glance suggests there may be another problem with this sort of Power Supply/Inverter board

[SilverArcher]

Re: Problem with Acer AL1715 Monitor

Sorry, it was overcast. I took some pics today. Also recheck all my solders they seem to be making good contact.

[Lumberjack777]

Re: Problem with Acer AL1715 Monitor

OK, this is going to be a 2 stage repair.

The first stage will be to figure out what went wrong with your cap replacement. You power/led should be solid. I suspect a problem with at least one of the capacitors. What type of capacitors did you use to replace the old ones with? Something went wrong with your capacitor replacement and you need to either use better capacitors or fix this issue.

Once you get a solid power/led light you can move onto stage 2.

The dimness is caused in the inverter section. Retiredcaps has an excellent guide called the 2 seconds to black. Your board looks very similar to the BenQ design. You need to test the 2 inverter transformers as it shows in the guide. But I think the problem is a shorted transistor. Notice the 2 transistors on both sides of the blue ceramic caps?(4 total) I believe 1 says Q211 on the board. One the other side it says Q218. There's 2 more I can't read the designator on the board. It's the 4 transistors on both sides of the blue ceramic caps. Test those as retiredcaps shows in the guide. https://www.badcaps.net/forum/showthread.php?t=10419

Start with post #19 and test the inverter transformers and the 4 transistors.

In summary. Redo the capacitors with high quality capacitors and get your power/led light solid. Then move on to stage 2 and test the inverter section. I'm thinking you'll find one of those little transistors is shorted.

[Rtech]

Re: Problem with Acer AL1715 Monitor

Lumberjack gives you what is probably the cause and that is faulty transistors,AND that may also be the cause of the led problem as follows.Initially you had the 5v feeding the Logic Board and so the power Led came on,and I suspect the faulty caps you replaced then allowed voltage to the inverter part ie the transistors,and if they are faulty that could change the fault symptom ref the led.So check and change the transistors as the first step and then see what happens.