Acer AL1711

[Demix]

Hey guys im back again =P

I thought this one would be no problem and I could do it without even bugging you guys but I guess i was wrong hehe.

Okay So I guess i will go ahead and say, usual symptoms.. switches on for a second then the backlights go off. So I opened it up to find Crapxon caps all over the place, I replaced the majority of these (all of them excluding a few tiny ones) I re-soldered the transformers and tested (well i say tested.. i tried to test :P im still new at this) the transistors, from what i understood they were okay anyways.. so I put it back together and still the same... although it now lasts for around 3 secs instead of an instant switch off. I unplugged the two monitor connectors in yellow and the screen stayed on for an extra few seconds, i tried variations of this and it seemed to me the problem is on that side of the PCB. Screenshots below of what I mean by the way hehe. Also below is a pic of all the caps i replaced (in red) and the fuses i tested (in red). and the area i think may be the culprit hehe. Anyways I wanted to know what you guys think i should do next now I have assessed that the probem is located somewhere on that side of the PCB, maybe the transistors really are gone? (even though i got the same readings back from them that the two on the other side gave me) or maybe i didnt re-solder the transformer well enough? I will give re-soldering properly another go in the morning but until then I thought i would use this time productively and let you guys take a look, Thanks ^^

-Demix

[PlainBill]

Re: Acer AL1711

Hey guys im back again =P

I thought this one would be no problem and I could do it without even bugging you guys but I guess i was wrong hehe.

Okay So I guess i will go ahead and say, usual symptoms.. switches on for a second then the backlights go off. So I opened it up to find Crapxon caps all over the place, I replaced the majority of these (all of them excluding a few tiny ones) I re-soldered the transformers and tested (well i say tested.. i tried to test :P im still new at this) the transistors, from what i understood they were okay anyways.. so I put it back together and still the same... although it now lasts for around 3 secs instead of an instant switch off. I unplugged the two monitor connectors in yellow and the screen stayed on for an extra few seconds, i tried variations of this and it seemed to me the problem is on that side of the PCB. Screenshots below of what I mean by the way hehe. Also below is a pic of all the caps i replaced (in red) and the fuses i tested (in red). and the area i think may be the culprit hehe. Anyways I wanted to know what you guys think i should do next now I have assessed that the probem is located somewhere on that side of the PCB, maybe the transistors really are gone? (even though i got the same readings back from them that the two on the other side gave me) or maybe i didnt re-solder the transformer well enough? I will give re-soldering properly another go in the morning but until then I thought i would use this time productively and let you guys take a look, Thanks ^^

-Demix

It is possible that one (or more) of the transistors are gone. I see several possible approaches. Which of those you take is up to you.

One approach is to determine if the CCFLs are working. You can either disassemble the LCD panel to the point you can see the CCFLs directly, rig dummy loads for the the inverter, or use a second set of CCFLs as loads.

Anther approach would be to replace the 4 caps I have circled in blue. These are in the inverter section, and are probably in the transformer drive circuits. One of those bad COULD be responsible.

A couple of other points. Two of the links between the inverter / power supply board and the logic board control the brightness (Bri) of the LCD and turn it on and off (On/Off). Try to locate those and make sure they to not change state when the backlight goes off. Also, I have circled an IC in yellow. What is the part number?

PlainBill

[Krankshaft]

Re: Acer AL1711

Yup the circled IC looks like the PWM IC for the inverter section I'm used to seeing them surface mounted.

I usually do a complete recap accept for the line filter. The low value caps are just too cheap not to replace.

[Demix]

Re: Acer AL1711

Thanks for the fast replys :-)

Well im sure the CCFL's are all working perfectly but i will check none the less (they all light up individually if i only plug 1 in at a time, the circuit just auto-shuts off). Anyway as for the IC I have a picture below with all the details for it, and I will look in to replacing those 4 caps then just in case, i guess i may as well as its best to replace the lot if i am replacing caps.

Thanks guys

-Demix

[Demix]

Re: Acer AL1711

Also about replacing the 4 caps in that area, i was looking to see what rating they were and i found two of them are 1uf 50v - fair enough, i assumed they would all be like that.. however when i checked the middle ones one of them says 2.2uf 50v and the other says 22uf 50v..... this just strikes me as strange, not that i know a thing about this really but i mean they all look exactly the same so maybe a manufacturing mistake? im not sure =P or maybe the "." on the 22uf one has just rubbed off lol

[Demix]

Re: Acer AL1711

Sorry for yet another post in a row =p i just wanted to post a pic + i wonder where i can find more of these transistors? Im fine with finding caps and fuses but any other component and i just get lost in the vast amounts of similar products =p

No really i just enjoy taking pictures.. lol xD kidding, anyways thanks again guys and ugh i do feel bad tripple posting lol, I used to be a mod on several reasonably large forums and i would have crucified anyone for doing this haha

[etnietering]

Re: Acer AL1711

Well I won't be much help on the first post - but about the middle one: It's perfectly likely that all those caps have different values, and that this is correct. I would guess they use the same can size just with a different label to save on manufacturing costs (economies of scale). I bought an assortment of caps a while back, and all of the caps from 0.1uF all the way to 47uF have the same can size.
And about the last one: I searched for 13N06 on digikey, and I'd say that the one you have is this one http://search.digikey.com/scripts/Dk...FQU13N06LTU-ND Unfortunately, they only sell it in packages of 5040. Mouser, however, has them for 80 cents a piece http://www.mouser.com/search/Product...jG1fWrqEnkqQ==

Good luck!

[Demix]

Re: Acer AL1711

I Replaced those 4 capacitors and resoldered everything to be sure and still no luck, im certain it must be the dang mosfets then, also thanks for the info etnietering =] hmm only problem about ordering from mouser is they charge stupid amounts for shipping to the UK for such a small order >_< ive been trying to locate a UK Seller who sells the FQU13N06's but i cant find a thing as of yet lol. Also I tested the CCFL's and they are fine, also if i switch them about and start the screen with 1 or 2 or 3 and in various orders etc i get slightly different results when i turn it on, some setups it swiches on shows the acer logo then the screens on for a few seconds, other setups it flashes on and back off without the acer logo etc. I know thats probably not important but still. Oh also its 100% the backlights as the screen stays on when the backlights go out. If i can get hold of some of these mosfets im sure it may solve the problem xD hehe ah well i better start looking at UK sellers

[Bobdee]

Re: Acer AL1711

I tested the CCFL's and they are fine, also if i switch them about and start the screen with 1 or 2 or 3 and in various orders etc i get slightly different results when i turn it on, some setups it swiches on shows the acer logo then the screens on for a few seconds, other setups it flashes on and back off without the acer logo etc. I know thats probably not important but still.

Yes that is important it tells you there is a fault on one side of inverter
Just a suggestion
As suggested and as you now assume its probably is a faulty fet
Check them to be sure, one pair will give you a much higher reading than the other pair (in circuit, with MM on diode setting)

[Demix]

Re: Acer AL1711

Yep I checked them out of circuit and bingo, 2 of them were fried giving me back strange readings (i still dont fully know how to test transistors in all honest, ive looked it up but its still confusing) anyways from what i understood atleast 1 of them was bad, so ive just ordered them from mouser, expensive yes but ive got a list of targets i want to complete by the end of the year and repairing all the current broken monitors i own is on that list =P lol

:Edit - Read your edit and ahh okay thats what i was getting so thats okay, one was coming back around 600 the other was coming back at about 350

[Bobdee]

Re: Acer AL1711

as they are out of circuit check them on continuity (buzzer or 200 ohms MM setting)
Looking for shorts between pins
Example 1+2
............1+3
............2+3
Any continuity and they are your bad ones

[Demix]

Re: Acer AL1711

managed to fix this screen but ruined it all lol >_< was just plugging the last ccfl in while the plug was in and everything was exposed, bad move I know.. so anyway I reached down to do it and got a MASSIVE electric shock which in turn made me pull my hand away sharp and drop the thing, so i ripped all the ribon bits attatching the screen to the ccfls lol, damnit! all that just to scrap this thing ¬_¬ its not my week.. hit by a car on monday and now shocked on wednesday lol

[lucky13]

Re: Acer AL1711

That rippon is detachable on a lot of the screens. Take a closer look. Some of them uses a fold down latch to secure the flat cable.

Otherwise, stay home Friday and take care of yourself ;-)

[Demix]

Re: Acer AL1711

Ahh no my friend I most definitely destroyed it when I dropped it :P Atleast i can put it down to experience and now i have an inverter which i can use to test other monitors CCFL's n such so its not a total waste =] i mean im sure i will come into a few more monitors with completely friend circuits but perfectly good screens i can swipe (if compatible) and use with this one so its all good, i was annoyed when I broke my other screen though, i was being so careful and managed to remove the screen bit with all its ribons etc, but i was heavy handed and you know the bit that plugs from the gfx board into the screen, i actually ripped that socket bit clean out lol =P oh dear.. i mean i think i could bodge solder it back but it would never be safe to use so i dont see a point =P also thanks for the kind words. Yeah its definitely not a great week for me so far, maybe things will pick up soon hehe =]