LG L1810B no life

[Thermaltake]

Hi, yesterday I got as a gift from one of my friend LG L1810B if I can fix it he is mine he said, problem is there is no life when I plug it and he said it is like that for a while. I reasearched a little bit and this power supply that this monitor have is same as in DELL 1800FP monitor. I read that main problem is soldering and that IC chip. As I look at my board I don't think that soldering is problem here because it look ok (check pictures) capacitors look fine too I mean I know that don't mean anything I have to measure them too but I will check that IC chip first I think It's him. My friend told me that I have to plug cord into power supply and measure pins(he gave me the picture how to do it, also attached) can someone confirm if that's okay I mean I don't have to push Power button right, just plug it and measure ? And does it have to be screwed on the back of the monitor or I can do It on the table unscrewed ? If anyone have anything else to add please do to help, thanks.

[Thermaltake]

Re: LG L1810B no life

And is this chip a good

http://www.ebay.com/itm/1pc-ICE2AS01...QAAOSwBLlVGp7U

It is ICE2AS01 but that letters and numbers under are not the same like on mine, is that a problem or that's just like some date when chip was made or something.

[Thermaltake]

Re: LG L1810B no life

Can someone help me please, are those solders good up there or not ?

And why some pins are solder like this (in red circle) is that normal ?

[Thermaltake]

Re: LG L1810B no life

And is this chip a good

http://www.ebay.com/itm/1pc-ICE2AS01...QAAOSwBLlVGp7U

It is ICE2AS01 but that letters and numbers under are not the same like on mine, is that a problem or that's just like some date when chip was made or something.

Okay I quote myself lol but I can't edit anymore so...
I just want to say I found out for those who have question like mine that those numbers and letter under the ICE2AS0 are manufacturer date and stuff that are not important if you look for that chip, important thing is just that ICE2AS0.

I bought one from ebay for 1.38$ and few more new capacitors so I'm waiting for them to arrive and resolder them with old ones and of course test monitor if he is working.

[momaka]

Re: LG L1810B no life

problem is there is no life when I plug it and he said it is like that for a while.

Check for standby voltage. It should be present on at least one of the pins on connector P902. For this voltage measurement, measure with respect to ground (monitor metal chassis), since this is the secondary side.

Also, post a picture that covers the whole solder side of the power supply board. That way, I might be able to tell you which pin(s) provides the standby voltage.

My friend told me that I have to plug cord into power supply and measure pins(he gave me the picture how to do it, also attached) can someone confirm if that's okay I mean I don't have to push Power button right, just plug it and measure ?

Correct.
The instructions your friend gave you to measure with respect to primary ground (pin 7 on that IC or the negative [-] pin of the big capacitor) are correct.

That said, the voltage you are getting on pin 6, Vcc, (13.8 Volts) suggests the ICE2AS0 PWM chip is working normally. If there was a problem, that voltage would pulse up and down (though, even this may be okay, as long as the voltage on pin 6 is above 8.5 Volts and below 21 Volts). Either way, I don't suggest you change this IC yet. I think the problem with the monitor may be elsewhere. Could even be possible that the problem is on the video board.

Once I see more pictures of the underside of the power supply and you determine that there is a steady standby voltage going to the video/logic board, then we should be able to narrow down where the problem is.

By the way, here is the datasheet for the ICE2AS0 IC, just for reference in case we do need it:
https://cdn.badcaps-static.com/pdfs/...5e0c7fe550.pdf

Can someone help me please, are those solders good up there or not ?

Solder looks okay to me. If it's cracked, you will see crack "rings" around the joint in many cases (though sometimes, they can be very thin and almost impossible to see).

And why some pins are solder like this (in red circle) is that normal ?

Yes, this is normal.
Sometimes, solder spots like that are used as "test" pads (where a needle or probe at the factory checks the voltages at those places). Other times, it it just leftover solder mask from a possibly previous (older) revision of the power supply board.

And does it have to be screwed on the back of the monitor or I can do It on the table unscrewed ?

I think you can test this power supply outside of the monitor. Just make sure to do it on an insulated surface. And preferably on something that isn't heat-sensitive and won't catch fire if a component blows or sparks on the board. Wooden table works well.

[Thermaltake]

Re: LG L1810B no life

Check for standby voltage. It should be present on at least one of the pins on connector P902. For this voltage measurement, measure with respect to ground (monitor metal chassis), since this is the secondary side.

Also, post a picture that covers the whole solder side of the power supply board. That way, I might be able to tell you which pin(s) provides the standby voltage.


Correct.
The instructions your friend gave you to measure with respect to primary ground (pin 7 on that IC or the negative [-] pin of the big capacitor) are correct.

That said, the voltage you are getting on pin 6, Vcc, (13.8 Volts) suggests the ICE2AS0 PWM chip is working normally. If there was a problem, that voltage would pulse up and down (though, even this may be okay, as long as the voltage on pin 6 is above 8.5 Volts and below 21 Volts). Either way, I don't suggest you change this IC yet. I think the problem with the monitor may be elsewhere. Could even be possible that the problem is on the video board.

Once I see more pictures of the underside of the power supply and you determine that there is a steady standby voltage going to the video/logic board, then we should be able to narrow down where the problem is.

By the way, here is the datasheet for the ICE2AS0 IC, just for reference in case we do need it:
https://cdn.badcaps-static.com/pdfs/...5e0c7fe550.pdf


Solder looks okay to me. If it's cracked, you will see crack "rings" around the joint in many cases (though sometimes, they can be very thin and almost impossible to see).


Yes, this is normal.
Sometimes, solder spots like that are used as "test" pads (where a needle or probe at the factory checks the voltages at those places). Other times, it it just leftover solder mask from a possibly previous (older) revision of the power supply board.


I think you can test this power supply outside of the monitor. Just make sure to do it on an insulated surface. And preferably on something that isn't heat-sensitive and won't catch fire if a component blows or sparks on the board. Wooden table works well.

Okay I'll do that.

One more question, how come then green led on monitor is not showing when I plug it, I mean If voltage is not coming to P902 I think green led would still show but monitor would have some problems turning on, right ?

here are picture of the whole board down and up

I forgot to mention I remove all the glue from the board I read it can make problems with conductivity after some time and turn brown (like case I had one Samsung LCD Tv).


EDIT:
Found a problem broken solder on D903 and on D906 that right one don't look good (pictures attached).
I will resolder them today. But when I resolder them can this happend again or was it just a factory fault with bad solder ?
Could just those solders be a problem or IC chip die when it cracked too ? I circled with blue color this solder it looks strange like solder was connected with that other solder and it's shorted or thats normal ?
And thermal paste under mosfets is dried and hard I know on PCs when it's like like that chip is heating up like crazy.

[momaka]

Re: LG L1810B no life

One more question, how come then green led on monitor is not showing when I plug it, I mean If voltage is not coming to P902 I think green led would still show but monitor would have some problems turning on, right ?

The power supply in this monitor has only one transformer. That means the power supply is turned ON all of the time, regardless if the monitor is ON or OFF.

Now, it's good that you provided those pictures (particularly, the solder-side shot), because I can see that connector P902 has the voltages labeled.
Pins 1 and 2 -> 12V supply (probably logic board and inverter)
Pins 3 and 4 -> ground
Pins 5 and 6 -> 5V supply (probably only to logic board)
Pins 7 and 8 -> ground

If you do some back-tracing, you will see that diode D903 with the bad joints is for the 12V supply and diode D906 is for the 5V supply. There is also IC905 - not sure what function it serves (my guess would be the PSU voltage output is lowered in standby mode and IC905 makes 5V from the 12V supply.)

Either way, with the monitor plugged in, you should definitely see 5V on pins 5 and 6 of connector P902 and anywhere between 7 and 14 Volts on pins 1 and 2. Let me know what voltages you get, though.

Therefore...

Found a problem broken solder on D903 and on D906 that right one don't look good (pictures attached).
I will resolder them today. But when I resolder them can this happend again or was it just a factory fault with bad solder ?

Yes, definitely re-solder those joints. Could well be the reason why the monitor is not working. Also, have a look at the joints for diode D901. One side appears to have a very small "ring" crack. Diode D901 is located right next to the yellow transformer. I suggest you re-solder both joints, just in case. This is the snubber diode for the primary side winding. If its joints go bad, it will make a lot of other things go in the power supply.

The bad solder joints could have been a factory fault, or they could have happened if the monitor was dropped or hit. Or it could be that someone else took the monitor apart before you and was too rough with it.

I also see that the leads on some of the capacitors are very long. Was the monitor recapped before? To me, it looks like it has. And Sam Young capacitors aren't that great in terms of reliability. I guess you can leave them in there for now. But you might have to recap the monitor again 2-4 years from now again (maybe more if you are lucky).

Could just those solders be a problem or IC chip die when it cracked too ? I circled with blue color this solder it looks strange like solder was connected with that other solder and it's shorted or thats normal ?

That's normal.
The solder connects the anode side to the cathode side through capacitor C923 and resistor R910. C923 and R910 form a secondary-side snubber network for diode D903.

And thermal paste under mosfets is dried and hard I know on PCs when it's like like that chip is heating up like crazy.

If you have some spare thermal paste, then feel free to apply a fresh new layer. The old paste probably dried because LCD monitors tend to run very hot inside - typically around 50-70C, and sometimes more.

[Thermaltake]

Re: LG L1810B no life

Now I just have to wait for new IC chip to come, I read that when that mosfets solder crack IC chip died if that's true I don't even have to measure IC chip I will just replace it with new one that I bought for 1,38$ pretty cheap. I don't know if someone disassembled the monitor after me, but I don't think so, because he was full of dust when I open it. They just bring it to me like that dead, and if I can fix it it's mine then I said okay why not I'll give it a shot.

I will replace both of those capacitors C907 50V 47uf and C924 25v 33uf with better quality Rubycon low esr one. Others look okay I mean they don't have bulged top, but if it's still not going to work after all the treatment I will measure the caps. and mosfets.

So I have to unsolder the mosfets put new thermal and resolder them again or bend them a little if that's okay I mean if they can hold bend remove that plastic behind them put new thermal and stick them back on metal. I don't know this whole putting a new thermal will take me forever I think, maybe I should leave it like it is.

[Thermaltake]

Re: LG L1810B no life

I noticed something on my PSU I have this zener diode, what is her purpose ? If she is protecting that IC chip maybe he is okay then, because on other PSU that I saw here on various topics on similar PSU from DELL monitors they don't have her. I need some details and explanation why is she on my supply and not on others is my like some revision 2 or something ?


On one of the topics budm said

...typical failure mode of the ICE2AS01: shorted VCC pin. You need to get the same IC, there is no sub for this ICE series IC. The later version of this power supply, they added 18V Zener Diode (Vcc pin to ground to clamp the max spike voltage to 18V) to stop the power supply from destroying this IC.

So I guess my IC chip is fine because of that zener diode I just need to resolder that mosfet and maybe change that caps around the chip. Ah there it goes 1.38$ in the air

[Thermaltake]

Re: LG L1810B no life

Forgot...

Is it okay if I replace those normal capacitors with low esr ones ?

[momaka]

Re: LG L1810B no life

Now I just have to wait for new IC chip to come, I read that when that mosfets solder crack IC chip died if that's true I don't even have to measure IC chip I will just replace it with new one that I bought for 1,38$ pretty cheap.

If the ICE2AS0 was bad, you wouldn't see the voltages you posted in this picture (especially the one in pin 6):
https://www.badcaps.net/forum/attach...8&d=1451921380

I will replace both of those capacitors C907 50V 47uf and C924 25v 33uf with better quality Rubycon low esr one.

Good idea.

Forgot...

Is it okay if I replace those normal capacitors with low esr ones ?

Yes, even better!

Others look okay I mean they don't have bulged top, but if it's still not going to work after all the treatment I will measure the caps. and mosfets.

Well, before changing anything, check the voltages on connector P902.

So I have to unsolder the mosfets put new thermal and resolder them again or bend them a little if that's okay I mean if they can hold bend remove that plastic behind them put new thermal and stick them back on metal.

Yes, you can bend the "mosfets" (they are actually common cathode dual diodes, and you will often see them called rectifiers) and apply thermal compound. No need to unsolder them.
But do NOT remove the silicone/mica "plastic" pad behind them! It is there for electrical isolation.

I don't know this whole putting a new thermal will take me forever I think, maybe I should leave it like it is.

You can leave it - at least for testing the monitor. Once we get it fixed, then you can change it.

I noticed something on my PSU I have this zener diode, what is her purpose ? If she is protecting that IC chip maybe he is okay then, because on other PSU that I saw here on various topics on similar PSU from DELL monitors they don't have her. I need some details and explanation why is she on my supply and not on others is my like some revision 2 or something ?

On one of the topics budm said...

Yes, that Zener diode (ZD902) is to protect Vcc (pin 6) of the ICE2AS0 IC from voltage spikes.

Ah there it goes 1.38$ in the air

Not really.
If you like playing with electronics (and power supplies, in particular), you can use it to build an SMPS.

Or keep that IC in your parts box until they become obsolete (i.e. no longer made). Then you can sell it for double or tripple the price.

[Thermaltake]

Re: LG L1810B no life

Can someone tell me is this glue under the mosfet or thermal paste I'm not sure because there is no screw only that metal holder.

[miclescu]

Re: LG L1810B no life

Can someone help me please, are those solders good up there or not ?

And why some pins are solder like this (in red circle) is that normal ?

hi,resolder D903 and D906.

[Thermaltake]

Re: LG L1810B no life

I am waiting for last capacitor to arrive and then I will start working on this PSU, I just need to know is that up on the picture glue or thermal paste ?

[lcdman]

Re: LG L1810B no life

Hello,

Its thermal paste.

Take Care,
lcdman

[Thermaltake]

Re: LG L1810B no life

Hello,

Its thermal paste.

Take Care,
lcdman

Thanks. I will change that paste too when I change capacitors.

But how is thermal paste doing it's job under that plastic thing under the mosfet, isn't that plastic blocking paste no matter if it's on both sides.

[momaka]

Re: LG L1810B no life

But how is thermal paste doing it's job under that plastic thing under the mosfet, isn't that plastic blocking paste no matter if it's on both sides.

That "plastic" is actually most likely a Mica insulator. Like this:
http://www.mouser.com/ProductDetail/...x4HNPDoaEIo%3d

Mica actually has good thermal conduction properties, and excellent electrical insulating properties. It provides electrical insulation between the MOSFET metal tab and the heatsink. Without it, your PSU will likely go as soon as you plug it in (or, at best, not start up at all.) The alternative to Mica insulators is Silicone insulators.

[Thermaltake]

Re: LG L1810B no life

It wasn't IC chip, two mosfets died 11N60C2 and 30CTQ060 I think that bad soldering got them dead. I order them today from ebay, will let you know more when they arrive and when I solder them.

[momaka]

Re: LG L1810B no life

It wasn't IC chip

Well, I don't like to say it like this, but... I told you so

(in posts #5 and #11)

Keep us posted what you find. I'm still reading this thread, at least.

[Thermaltake]

Re: LG L1810B no life

I didn't have much time to update this, but few days ago I replaced Q902,D906 mosfets, and after that glass fuse f901 blow up, any idea why and where to look anyone ?