Acer AL718: It Goes On And Off

[RainbowSix]

Hi everybody, just found this great forum. A friend of mine gave to me (free) an "old" Acer AL718, it was working but last week it started, when powered up, to go on and off continuously. In a first time when I tried it, it was going on with clear picture, then after 10 seconds went off, and the only way to make it work, was unplug and replug to ac power. In the second time, after disassemble and a few testing, it started to goes on and off, on and off. I can see just a moment the picture clearly, then it goes black and it start to cycle on and then off. This display does not cost so much (about 30$ on Ebay here in Italy), but just for fun, I would like to see if I can repair it. Looking at Psu I can't see any bulging or leaked cap. Here are 2 pics about the Psu board. Any help appreciated

[PlainBill]

Re: Acer AL718: It Goes On And Off

Excellent pictures. What is the brand and series of the capacitors? The series is a two or three character identification; it often precedes the temperature rating of the cap. If necessary, post the complete information from the caps and we can pick the series out.

Odds are they used off brand caps in this, If so, the best approach would be to replace ALL of them (with the possible exception of those in the audio section).

PlainBill

[RainbowSix]

Re: Acer AL718: It Goes On And Off

Excellent pictures. What is the brand and series of the capacitors? The series is a two or three character identification; it often precedes the temperature rating of the cap. If necessary, post the complete information from the caps and we can pick the series out.

Odds are they used off brand caps in this, If so, the best approach would be to replace ALL of them (with the possible exception of those in the audio section).

PlainBill

Brand is Ltec, series is LZG. Thank you

[PlainBill]

Re: Acer AL718: It Goes On And Off

Brand is Ltec, series is LZG. Thank you

A couple of comments on Ltec are posts 2 and 4 of this thread. Replace them, I recommend Panasonic FC - don't forget to make sure they are the same physical size.

PlainBill

[EGuevarae]

Re: Acer AL718: It Goes On And Off

A couple of comments on Ltec are posts 2 and 4 of this thread. Replace them, I recommend Panasonic FC - don't forget to make sure they are the same physical size.

PlainBill

I agree with PlainBill. Replace all those LTec while you are there, with Panasonic FC or FMs. - Watch for height, as PlainBill advised -
And Welcome to the forums!

[cjmclellen]

Re: Acer AL718: It Goes On And Off

And if that doesn't work, check Q153 and Q156 inverter IC's (i think that's what they are labeled as). Check for shorts across one side to the next. I usually just "rake" my red probe down one side of the IC and the black probe up the other side.

In actuality, one side of these IC's is ground (4 pins) and the other side (4 pins) +power. Just leaving the black probe on the ground side, you can touch the other sides' 4 pins with the red probe. Put your meter to the "beep" setting, checking for continuity.

Any short circuit found across an IC like this is usually not good. And I've seen this actually cause the unit to power cycle (like yours is), and even cause some not to power on at all.

[RainbowSix]

Re: Acer AL718: It Goes On And Off

Replaced all the electrolytics and the X2 type, worked like a charm, thank you for all the tips

[Solder Boy]

Re: Acer AL718: It Goes On And Off

Nice job on the repair.. just a question from this LCD repair newb.. what exactly is meant by 2X type?

I saw it noted on your photo.. did you replace the fuse or did you replace those two coils? TIA..

[sofTest]

Re: Acer AL718: It Goes On And Off

Nice job on the repair.. just a question from this LCD repair newb.. what exactly is meant by 2X type?

I saw it noted on your photo.. did you replace the fuse or did you replace those two coils? TIA..

X2 is a film type capacitor, i.e. in this case the beige box on the photo.

[nick2012]

Re: Acer AL718: It Goes On And Off

Same problem with my Acer x223hq,go on and off continuis while diplaying Acer logo and
windows screens after few seconds picture go's black and endeless repeats the
process upon powering off

Mvg,

[newtothis]

Re: Acer AL718: It Goes On And Off

Check caps and replace

[nick2012]

Re: Acer AL718: It Goes On And Off

Caps look al clean and not bulged,wil later post a' picture.

[nick2012]

Re: Acer AL718: It Goes On And Off

Look at the power bord ?
looks like new,but will replace the Caps ,to be shure.

[budm]

Re: Acer AL718: It Goes On And Off

"Same problem with my Acer x223hq,go on and off continuis while diplaying Acer logo and
windows screens after few seconds picture go's black and endeless repeats the
process upon powering off" Does the power LED also going on and off at the same time?

[nick2012]

Re: Acer AL718: It Goes On And Off

yes the Led go from bleu to orange and off and starts alover again endless loop,

see youtube video that i' put on.

https://www.youtube.com/watch?v=8cmHyl4a4oQ

I there a solution for this defect ?

[budm]

Re: Acer AL718: It Goes On And Off

The on-off cycling can be due to the power supply is over loaded so it goes into shutdown/start-up cycling mode.
Can I see the back side of the board? We can try disconnecting the inverter circuit from the power supply section to see if it will stay on.
You can also check the DC voltage right at the two legs of that 120uf main filter cap to see if it also has large variation, the voltage on that cap should be about = 230V * 1.414 = 325VDC

[nick2012]

Re: Acer AL718: It Goes On And Off

I' will try that later tomorow

[nick2012]

Re: Acer AL718: It Goes On And Off

The main bleu filter cap shows a steady 319/320VDC ! so that is then defective,en shut
first to be replaced?
also I made a' test bench see the picture ,And when I ad curent to the main board and
withoud the screen atached ,then the bleu LED stays ON ,so this might be good I hope.

the bench piture.



The backside of the power board.





Top view.




Nick

[budm]

Re: Acer AL718: It Goes On And Off

OK, it is good that the power LED stays on solid, next thing to do is to connect all four lamps connectors to the board, still leave the ribbon cable disconnected, you then should see the backlights stay on.

[nick2012]

Re: Acer AL718: It Goes On And Off

ok will test it .