Acer X223w ... keeps resetting after 5 minutes of warming up

[Porto]

Hello,

As the title says, I have this problem with this monitor that works fine for about 5 minutes and then it constantly keeps resetting (LED goes off, LED goes yellow, LED goes green with ACER logo in screen) etc etc.

I have desoldered all the electrolytic caps on the power board and measured them for capacitance and ESR and all seems to be within specs; none of the caps has visible damage. I also reflowed the power transformer.

Very likely something is becoming hot, too hot and goes in overheat protection... I suspect the mosfet or transistor on the right, with the heatsink on it, that one is becoming quite hot. Only, the text on it is made unreadable so I don't know what it is exactly...






Anyone have suggestions what to do next?

[budm]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

Monitor the DCV feeding the logic board to see if it drops out.

[Porto]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

Monitor the DCV feeding the logic board to see if it drops out.

I will do that after repairing some stupid mistake I just made.

That transistor on the right is a mosfet, hence the letters G,D and S printed very small on the board at its legs. I wanted to measure the voltage on the Gate but slipped with the probe and it hit the Drain and shorted out the mosfet immediately!

The 5v to the logic board has turned into 150v now and ofcourse the monitor won't power up at all.

Argh, have to be more careful when probing a live board!

[stj]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

you may have blown the driver ic if you shorted the gate.

btw, i had a tv doing similar stuff, it as the output rectifier for the low voltage.
once you get the fet sorted, meter the 5v and if it slowly drops, meter the ac side of the output.

[ben7]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

The 5v to the logic board has turned into 150v now and ofcourse the monitor won't power up at all.

Uh, I think you will need a new logic board if it put out 150V!!!!!!!

Yeah, !@#t happens, even to experienced people!

[Porto]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

And y'all must be right, I blew some tiny IC and a resistor on the back of the board; I even didn't notice it at first, but it's quite obvious!
(those holes must be the litte pops I heard!)



I found a service manual and it possibly an SG5841J PWM-controller? I'm not quite into mosfet driver chips but can this be the one?

Also that mosfet was a 2761i n-chan, 650V, 10A one... I replaced it with a STP20NM505 nchan, 550v, 20A... but ofcourse the problem stays.

I even suspect all the surrounding resistors have gotten a beating and even that yellow transformer.

I got this monitor for $15 so it's not a great loss, but it's not quite an example repair!

[ben7]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

And y'all must be right, I blew some tiny IC and a resistor on the back of the board; I even didn't notice it at first, but it's quite obvious!
(those holes must be the litte pops I heard!)

I found a service manual and it possibly an SG5841J PWM-controller? I'm not quite into mosfet driver chips but can this be the one?

Also that mosfet was a 2761i n-chan, 650V, 10A one... I replaced it with a STP20NM505 nchan, 550v, 20A... but ofcourse the problem stays.

I even suspect all the surrounding resistors have gotten a beating and even that yellow transformer.

I got this monitor for $15 so it's not a great loss, but it's not quite an example repair!

You'll need to replace the IC, any blown SMD resistors/diodes (check them with the ohmmeter!), the fuse (F801), and check the pink resistor near the heatsink where you shorted the FET. (Can't see it's component number clearly) It's a low ohm resistor, so if it is a good, don't be surprised if it looks like a short circuit.
It might even also be possible that the optocoupler has been blown, so you might want to replace that too. And just check all the components in this area of the board, to be sure you will replace all faulty parts. (There are a few through-hole parts that I can see are near/involved with the "accident site" xD
Also check the green thermistor thing near the AC inlet, sometimes dead/severe shorts can cause those to blow and go open circuit.

Also, I don't think that is a SG5841J, you can see it only has 7 pins when the SG5841J has 8!

-Ben

[Porto]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

Ben, I will check it all!

I finally found the right power board schematic. They say it uses the power board from the X223W, but it seems this is a power board for a X223HQ version, the ILPI-139.



It seems the IC is indeed a 7-pin PWM controller, the NCP1337.

http://html.alldatasheet.com/html-pd...1/NCP1337.html

The mosfet is the same as on the X223W power board, the 2761i.

NOW I can try and repair this thing!


BTW: I read in another topic that someone with exact the same problem with the HQ version had changed the power IC because it overheated... but which one IS the power IC to check?

[stj]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

power ic would be the NCP-leet or the fet.
so either way, your replacing it!

[Porto]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

power ic would be the NCP-leet or the fet.
so either way, your replacing it!

LOL!

Thanks!


BTW: now got myself an HP 2510i monitor with the ILPI-162 powerboard.
Monitor is completely dead, but after measuring 2 mosfets and one diode as per this youtube movie,
I'm certain I've found the problem with it!

https://www.youtube.com/watch?v=1tm5TosySAA

https://www.youtube.com/watch?v=pjFJdlAmSHs

Hopefully I won't blow this one also!

[Porto]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

At last got the right mosfet controller delivered and also replaced all the blown parts with parts out of a broken PC power supply.

The monitor is working perfectly!

It did go off after some minutes of running but now I have it test-running for like 30 minutes and it's holding firm... I'll keep it running for another 2 hours but I think I've repaired this monitor for sure!

Everyone thanks for the input!

[anton.tfile]

Re: Acer X223w ... keeps resetting after 5 minutes of warming up

Porto, hi!
Do you have the picture of the motherboard of monitor Acer X223.
I need a full picture of the other side of the board.
It was a lightning and most of resistor were burned.
My email: anton.tfile@yandex.ru