Samsung BN44-00505A(PD23A0Q) psu, smd transistor types

[budm]

As I indicate thee board in question does not have PFC, but you still have SMPS circuit that will still generated the back EMF by that power transformer, please read up on when happen when energize and deenergize inductor then you will understand why they put in the 1000V higher cap in that section. That cap is exposed to much higher that 330vdc.
http://i.stack.imgur.com/REXp2.png look at c12 which has the same function as CM804 of your power supply board.

http://electronics.stackexchange.com...details/254675

http://ww1.microchip.com/downloads/e...tes/01114A.pdf
See page 13, (F) = Voltage across the MOSFET Q1
BTW, common failure mode of ceramic cap is shorted circuit.

[modrobert]

Originally Posted by Chungalin

Let me question the cause-effect order of this apparently recurrent failure. If ceramic capacitor is 1KV rated, and the TV is powered from 230V AC, at that point of the PSU there’s nothing that can generate more than 1000V. I’m starting to think that it’s the capacitor that fails first. The IC gets shorted because the cap shorts briefly before blowing to bits. What else can make a ceramic capacitor explode this way?

I see no problem in removing the white insulation glue. I use a small flat screwdriver to remove some big chunks and then I unsolder the IC. Once all legs are unsoldered, just pull the IC and all the glue that comes with it.

Thanks for the tip, will try to get the last gunk off after desoldering the bad parts, still waiting for the replacement parts.

I was just assuming the STR-W6052S failed first because in my experience with power supplies MOSFETs usually fail while ceramic capacitors rarely do so.

After looking at the datasheet for STR-W6052S I'm starting to understand it a little better, they have sample schematics in there which seems to match the board. I'm a bit of a rookie with this type of circuit though, anything involving high voltage stuff. On the bright side, at least I learned something new today, figured out what a "damper snubber" cap is.

[budm]

"usually fail while ceramic capacitors rarely do so. " if look through lots of threads at BC and fix lots of circuit in that power supply section you will this type of caps failed in this application and we also recommend going with even higher Voltage rating.

"After looking at the datasheet for STR-W6052S I'm starting to understand it a little better, they have sample schematics in there which seems to match the board. I'm a bit of a rookie with this type of circuit though, anything involving high voltage stuff. On the bright side, at least I learned something new today, figured out what a "damper snubber" cap is."
You should also look at the board and see how cap CM 804 is connected to the STR also, it is basically connected across the switch (Source and Drain, Pin 1 and pin 3 of the STR) in this case it is the internal power MOSFET inside the STR.

[modrobert]

OK, the LCD TV (Samsung model UA23F4003AR) works again, thanks for the help.

I had to replace the power IC (STR-W6052S), capacitor 220pF/1000V (CM804), resistor 0.36 Ohm (RM803), and the fuse 2A/250V (FP802S). Also had to solder a wire to fix a PCB trace that had burned off between resistor RM803 and the heat sink point for STR-W6052S.

[bansai]

Hi All.
I have the same power supply. After a power surge burned a lot. Help determine the capacitor SM853, it is not on the board, after another workshop.
Sorry for the translation in Google.
Thank you for your help.

[totof]

Originally Posted by bansai

Hi All.
I have the same power supply. After a power surge burned a lot. Help determine the capacitor SM853, it is not on the board, after another workshop.
Sorry for the translation in Google.
Thank you for your help.

Hello,
A have the same board as you and there is no SM853 capacitor.
On the other hand there is a CM853 capacitor (electrolytic, 47 microF, 50V).

[josecami]

Bn44-00505a

[xipbox]

Can anyone help-me with this borad to?!
my problem is DM861 (SR320 ), I replace it but it burns.. any idea ?!

[magos21]

I can't see the type of diode DM855 snd DM852 ,can anyone tell me the type or sent me the service manual?

[Liamcabrera]

Good afternoon, I have a question, I have a BN44-00505A source but bring the strw6053s, in my country I am not getting it, I also burn the capacitor 220pF / 1000V (CM804), the resistance of 0.36 Ohm (RM803), my question is the Next can I replace the 6053s with the 6052s? , my doubt is the difference of watts that the two integrated handle, I hope a quick response, thank you very much.

[Chungalin]

STR-W6052S is 60W, while STR-W6053S is 90W, this is why it’s not safe to replace 6053 with a 6052. But you can replace 6052 with a 6053.

[toxadi]

Originally Posted by magos21

I can't see the type of diode DM855 snd DM852 ,can anyone tell me the type or sent me the service manual?

DM852? Do you mean DM853?

DM855 is SF36G.

Το έφτιαξες;

[rruna1971]

Hi All,
For the record, and help someone, i replace the rectifier bridge was short circuit, the fuse was open, put new one, the diode DM801 was with dark burned area, replaced, the CM804 was with visible crack, replaced and after all this, didn't start. I replaced the STRW 6052S and, worked.

[roberto77]

My Samsung T24B301EW broke, blue status LED is on, so there is some power, if trying to switch it on the LED blinks 3-4 times slower then blinks very fast, nothing happens.

Found this thread, trying to understand, whats going on.

Took a look at my PSU BN44-00505A, some pictures here: https://imgur.com/a/AnmN8sD

CM855 seems to be damaged, could it be the only reason for behaviour? Can you pro people maybe spot other damage or suggest which parts I should inspect further?

Trying to locate other parts mentioned in thread, seems I can not find that STR-W6052S, any hint where to look?

Am a beginner, not totally clueless but bare with me please, have soldering iron and simple voltmeter. Managed to fix a dead old harddisk a few month ago with motivation from Louis Rossmann videos, "just try it" attitude, a lot of google, ordering and exchanging mainboard and switching smd rom chip with borrowed hotair station.

[roberto77]

FYI, replaced CM855 with a new 10 V 1200 µF, TV works again.

[Atavares]

Originally Posted by xipbox

Can anyone help-me with this borad to?!
my problem is DM861 (SR320 ), I replace it but it burns.. any idea ?!

Hello! I have the same problem, is the QM861 it´s in short circuit, but i cant see the reference,,, i need the service manual or the ref. anyone?

[tacosgr]

Hi All,
First time posting , i would like to thank all of you in this forum giving your experience and knowledge to all of us .My TV is T22B350EW and the power supply is BN44-00505A(PD23A0Q) , i replaced the rectifier bridge it was short circuit replaced , the fuse was open, put new one, replaced the CM804 was with visible crack, replaced the STRW 6052S and , worked.

[fardelejo]

Originally Posted by Chungalin

I have replaced IC STR-W6052S, ceramic cap [CM804] (0.22nF 1000V "221K 1KV") and the TV is working again.

Same happened to me, burned Ceramic Cap, but no VCC on switcher, so replacing both IC and cap, worked again.

Many thanks for your help, this thread helped me a lot.