Samsung 23" LCD P2350 Inverter Repair

[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?

[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

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

Do I need one or two?

[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?

[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

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

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

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

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

Look at the attachment

[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

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.

[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.

[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.

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

I will try posting it

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

As I said in your other thread and someone else also mentioned we 'think' you have to replace like with like ie1200ohms with 1200 ohms OR perhaps change some resistors or something so that the protection doesnt kick in and switch the lamps off.
Unfortunately I dont know enough to be certain.
Perhaps ask the question in general electronics. eg "can I replace a faulty inverter transformer with 1200 ohm secondaries with a transformer with 1600ohm secondaries.
or visa versa and if not why not?

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

for am4512c I would have to wait about month or two... Both secondaries ar exactly at 1,68kOhm and the one I replaced had one at 1,21kOhm and other at 98kOhm. What could be the problem now?

[selldoor]

Re: Samsung 23" LCD P2350 Inverter Repair

AM4512C is available on ebay the important thing on inverter transformers is that the
secondary windings should measure the same (within 3%) if there are two secondaries on one transformer. If the transformer has only one secondary then it should measure the same as the other transformers if there is more than one lamp.
If there is a number of transformers ,as is often the case on a tv inverter board, each transformers pair of secondaries should be the same and every transformer should be the same.

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

mosfets had gates shorted, no replacements so I did the same fix like in post one... thought i have it fixed when it turned on but it turned off in a few seconds... now the red led stays on but the screen keeps shuting down after 2 seconds... did I put in the wrong transformer, does it need to have both secondaries at 1,21 kOhm cause I thought the most important thing about transformer is primary/secondary ratio

[Rtech]

Re: Samsung 23" LCD P2350 Inverter Repair

This might help.

http://www.4qdtec.com/mostest.html

[CroTech]

Re: Samsung 23" LCD P2350 Inverter Repair

The problem is mosfets are so small i cant read what is written on them... I will try taking a picture of it then zooming in. I read that u need a bias current so u can check a mosfet?