Samsung 23" LCD P2350 Inverter Repair

[budm]

Re: Samsung 23" LCD P2350 Inverter Repair

I would suggest getting the correct transformer, you haver to match the DC resistance which you can check with the Ohm meter, but you also need to match the inductance of the transformer, and also the input/output voltages, the current output, so it will put out correct high voltage to fire up the lamps.

[jetadm123]

Re: Samsung 23" LCD P2350 Inverter Repair

The power board in post #11 uses a QGAH02113 inverter transformer available here:

http://www.ebay.com/itm/QGAH02113-In...item2578c0e1b3

Don't know if it will work because you may have a different revision of the same board. Perhaps budm, selldoor or others may have a comment about this.

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

the original inverter is this http://www.ebay.com/itm/Inverter-Tra...-/250862284136
I will buy it and replace it and then I´ll get back to u, many thanks.

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

the original inverter is this http://www.ebay.com/itm/Inverter-Tra...-/250862284136
I will buy it and replace it and then I´ll get back to u, many thanks.

Just out of interest did you test the old one - which pins?

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

Look at the attachment

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

transformer came in today... Has both secondaries at 996Ohm
Nothing changed, the monitor keeeps shuting itself down after 2 seconds

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

That is bad news, have you any spare ccfl bulbs or anything you can test the panel from this one in. ( Could be a faulty bulb or wiring)

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

nope, I dont have cathod bulbs.... I could buy one then test it.
Should I check anything else

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

I dont know exactly what you mean by cathod bulbs. I dont know if you have seen it but Budm has this - its a lot cheaper just for a test than buying ccfls.
https://www.badcaps.net/forum/showth...ght=test+lamps.

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

Cold Cathode Fluorescent Lamp = cathod bulb, just my term...
I could buy one ccfl tomorrow, but how many wats and any special specifications?

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

Will this one do the thing?
http://www.chipoteka.hr/artikl/95450...#tab-specs-tab

Do I need one or two?

[budm]

Re: Samsung 23" LCD P2350 Inverter Repair

Since you had indicated earlier that some of the MOSFETs had blown, did you rechek them?
Notes on the lamp per your link, I never try that kind of form factor, I tried other form factor, the twisted type as shown in my pictures work. I will have to get one like the one in your link to try out.

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

Yup, earlier monitor had the same symptoms as now... It turned on and off after 2 seconds, so I checked the inverter transformer and it was faulty, replaced the transformer and again it worked for 2 seconds and then nothing, I could not even turn it on, not even the LEDs, so I found out that the MOSFETs were shorted, so replaced them too, and now I have 2 seconds to black again.
Do u mean to check the new MOSFETs?

And, I´ve read that you can check the CCFLs without having a spare CCFL bulb, u can just unplug one connector and than try?

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

Checked out what PlainBill said about testing CCFLs... Unpluged one connector on the CCFL turned on, same thing 2 seconds to black only the brightness is 50% lower, pluged back in the one that was dsconnected, and disconnected the one that was connected in the previous test and the same thing happened again...

SO! I assume the problem is still in the power board unless both CCFL lamps are dead which I assume is not quite possible?

And the MOSFETS are OK

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

I dont know plainbills post but retiredcaps has similar in his 2 seconds to black guide. My understanding is that that one lamp test is ONLY a quick test to find out if a lamp (or the wiring)is definitely broken as against being faulty.
Using lamps that you KNOW are good is the best test. -

"Do I need one or two?"

It is easier if you have 2 test lamps.

[budm]

Re: Samsung 23" LCD P2350 Inverter Repair

I use test lamps for real verification of the inverter function.
Yes, it is very possible to have two bad lamps in the assembly as you can see here:
http://s807.photobucket.com/albums/y...klight%20lamp/

I have los of spare lamps!

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

buying 2 test lamps costs a lot... so I am thinking of buying those
checked the voltage regulators just out of curiosity, 3,3V gives 3,29V and 1,8V gives exactly 1,8V so those are fine too
now there is nothing else suspicious other than CCFLs?

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

Before you do that there is another thing you can try.

First find a pin on the main board connector labelled pson or pwr
Set it all up but without the main board connected then get a 3 volt battery or 2x1.5v
wire the negative of the battery to ground screw and apply the 3v from the battery
to the psonpin. With any luck the lamps may light.

It is difficult for us to say if there is anything else as we have not seen pictures of your boards.

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

So I should apply 3v here, like on the picture, with only power board and CCFLs connected?

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

Yes Pin 8 power and ccfls.

Have you tested the fuse at F201? that takes the power to the inverter.