Samsung LNT3242HX/XAA (BN44-00192A)No picutre

[jretropie]

Hi friends,
I have a Samsung TV LNT3242HX/XAA with a power supply board BN44-00192A
No image, No back light, (no sound when I press the front buttons)(only red light on the button)

Checking the PS board, all the connector pins read 0 except for the Standby pin 5V.

Took the PS board out and I short the standby and PS pin, the Voltage on the big capacitor read 385Vdc.

I have try to clean the glue but make no different. I don't have anything on hand to test capacitors.

[budm]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

The main board is not sending the PS-ON to turn on the rest of the power supply.

[jretropie]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

Put my cheap multi-meter and I measure the "RM801"(0.22Ohm 1W) and get no resistance. Could this be the problem?

The main board is not sending the PS-ON to turn on the rest of the power supply.

[budm]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

Blown resistor, you also need to test those two MOSFET's on that heatsink next to that blown resistor.

[jretropie]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

How do I test MOSFET? I got zero voltage Vdc on all the legs.

Blown resistor, you also need to test those two MOSFET's on that heatsink next to that blown resistor.

[budm]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

You will use Ohm mode to check for very low resistance readings between Source and Drain pin. That resistor may have blown due to shorted MOSFET or shorted snubber cap (connected in parallel with S and D of the MOSFET).

[jretropie]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

Is this two points on the picture is the Source and Drain?
I got 10ohm on each on them.

You will use Ohm mode to check for very low resistance readings between Source and Drain pin. That resistor may have blown due to shorted MOSFET or shorted snubber cap (connected in parallel with S and D of the MOSFET).

[budm]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

That Source and Gate. Source and Drain are the two big solder pads.
You should look up the spec sheet of those MOSFET's to learn about the pinout of those two MOSFET's.

[jretropie]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

The two big solder pads has no resistance.

No continuity.

Does this mean is bad?

That Source and Gate. Source and Drain are the two big solder pads.
You should look up the spec sheet of those MOSFET's to learn about the pinout of those two MOSFET's.

[budm]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

That is good.
That 0.22 Ohms resistor is the Fusible resistor for feeding the 385VDC PFC Boosted Voltage to run the 24VDC SMPS section.

[jretropie]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

Thank you very much for your help!

Replaced the resistor and now I get picture. I am going to test more and see.

That is good.
That 0.22 Ohms resistor is the Fusible resistor for feeding the 385VDC PFC Boosted Voltage to run the 24VDC SMPS section.

[budm]

Re: Samsung LNT3242HX/XAA (BN44-00192A)No picutre

Thanks for the follow-up.