Samsung PS replacement

[anupkg1985]

Re: Samsung PS replacement

Since the bridge and the resistance test on the main cap are OK, all you have to do now is to replace that snubber cap, then you can try powering up the board by putting 75W 120VAC incandescent lamp in place of the fuse, if the lamp comes on bright and stay bright then you have more problem on the board..

That sounds like more kind of adventure, something better than writing software code Will try it and post the results. One question, can I use LED bulb in-place of incandescent lamp?

[budm]

Re: Samsung PS replacement

That sounds like more kind of adventure, something better than writing software code Will try it and post the results. One question, can I use LED bulb in-place of incandescent lamp?

It has to be incandescent lamp.

[anupkg1985]

Re: Samsung PS replacement

I replaced bad capacitor with 1nF capacitor as I had that only in spare. I did lamp test and looks like there is more problem with PS as lamp was lit and bright for longer time almost more than 10 seconds then I switched off the circuit. Let me know what should i check further on circuit?

[budm]

Re: Samsung PS replacement

Is the cap rated at least 1000V? 1nF is 1000pF way too much from 68pF. Wrong size cap can cause damage to the SMPS IC, they choose 68pf for reason.
How many Watts is that lamp? 75W? It does not look like 75W lamp.

[anupkg1985]

Re: Samsung PS replacement

Is the cap rated at least 1000V? 1nF is 1000pF way too much from 68pF. Wrong size cap can cause damage to the SMPS IC, they choose 68pf for reason.
How many Watts is that lamp? 75W? It does not look like 75W lamp.

Cap is 1KV and lamp is 45W, not sure if that is fine. I couldn't find any other lamp as i replaced all with LED lamps.

[budm]

Re: Samsung PS replacement

OK, for now with the set up you have, what is the DCV between the two legs of the main filter cap (larg lytics cap rated at 450VDC)?

[anupkg1985]

Re: Samsung PS replacement

I tested with this setup again and now lamp stays on for 5-6 seconds then goes off. VDC on main cap measures around 390V and also has 12.9V on PIN1 of the out pins. Let me know whats wrong now or is it working fine after replacing the bad cap? Do I need to do further checking on the board?

[budm]

Re: Samsung PS replacement

I tested with this setup again and now lamp stays on for 5-6 seconds then goes off. VDC on main cap measures around 390V and also has 12.9V on PIN1 of the out pins. Let me know whats wrong now or is it working fine after replacing the bad cap? Do I need to do further checking on the board?

Good, so that power supply section is working, the PFC Voltage booster is also working.
So just put in the right value of that ceramic cap then it should all be good.

[anupkg1985]

Re: Samsung PS replacement

Replaced cap with 68pf 1KV as didn't get 2Kv and TV is back on working as expected.
Thanks to budm!!!

[budm]

Re: Samsung PS replacement

Thanks for follow-up on repair.
I am glad that it is just simple failed cap replacement.
Make sure to turn down the backlights level (Not Brightness) on all input to help extending the life of the LED's.