Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

[gdulisse]

Hi, I have a Samsung LN52A550P3FXZC 52" TV with a power supply board BN44-00200A.

The TV blew both T6.3A 250V ceramic fuses on inspection with my meter. So I went to replace them and then powered a thermistor (Inrush Current Limiter) NT811S which is an 8 Ohm on by the schematics and marked SCK 084 on it blew up real good. This is the one next to the relay (see the picture attached).

All the caps look good. Not sure if I should replace the relay or anything else though.

I need the specs for the thermistor above if anyone can help me out plus any other advice on what needs to be replaced.

Thanks in advance
Giancarlo (in Canada).

[budm]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

You have badly shorted out devices, start checking the resistance of the 3-leg devices and the bridge rectifier mounted on the heatsinks.

[gdulisse]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

You have badly shorted out devices, start checking the resistance of the 3-leg devices and the bridge rectifier mounted on the heatsinks.

Yes, tested them all and they are fine. I don't think anything else is blown since the thermistor blew at the same time one of the main fuses which will break the circuit (to the main rectifier anyhow) on this board (see picture). At least I hope.... since I unplugged right away.....

[gdulisse]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

So looks like it is an SCK-084 which is the same as an NTC SCK13-084. See specs attached (FYI for anyone else looking for these).

[drpj23]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

Even if nothing else got damaged/blown, something took out that thermistor and fuse, both of which are for circuit protection. So there is still an existing short, as budm has said, that caused it. I would check diodes too.

[anmol]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

Here is schematic for BN44-00200A.

wbr

[gdulisse]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

Here is schematic for BN44-00200A.

wbr

Thanks, I have this. I will see if I can figure out what else has been affected. I only have a multi-meter so is there a way to determine if a diode is bad other than continuity test? I will have to research how to test some of these components better but I fear without a scope it will be difficult.

I have ordered a new board so this is more to see if I can fix the existing one.

So if I unplug all of the connectors except the ground, and power connector is that better in terms of limiting any damage?

Thanks again
Giancarlo

[tom66]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

When diodes fail, they almost always go short.

[budm]

Re: Samsung LN52A550P3FXZC power supply board BN44-00200A thermistor

OK, put in a new fuse, put a jumper across the blown Thermistor, then take the resistance reading at the AC plug Hot and Neutral and tell us what you get.