Samsung LN-S4041D Repaired... Not Quite

[rxchng]

I have some experience in replacing bad caps on several power supplies (primarily ReplayTVs) in the past and all went successfully.

Recently, my Samsung 40" LCD HDTV (Model LN-S4041D, Hansol Board BN44-00134A) all of a sudden was experiencing the common black screen problem but audio ok. Thinking that it was the power supply again, I ordered some good quality caps (some Rubycon and some Nichicon) on the internet and replaced a total of 7 caps (some bulging and some had no signs of problem at all, they just happened to be around the same area) on the board.

After that, the TV was running like new the first night for hours. I was so excited that I fixed another electronic equipment. But then the next morning, it turned on for just several minutes and then the black screen again, again audio was ok. I switched it off and back on again, the TV would stay on for another several minutes and went dark again, no sparks, no clicking sound or anything, it just went dark. The audio is always ok.

What else could be the problem? There are other caps scattered on the board that I didn't touch, such as several 50V 0.22uF, 50V 10uF, 50V 47uF and the giantic 450V 220uF cap. Should I replace those or am I in the wrong track?

Any ideas will be greatly appreciated. Thanks a lot!

[PlainBill]

Re: Samsung LN-S4041D Repaired... Not Quite

I have some experience in replacing bad caps on several power supplies (primarily ReplayTVs) in the past and all went successfully.

Recently, my Samsung 40" LCD HDTV (Model LN-S4041D, Hansol Board BN44-00134A) all of a sudden was experiencing the common black screen problem but audio ok. Thinking that it was the power supply again, I ordered some good quality caps (some Rubycon and some Nichicon) on the internet and replaced a total of 7 caps (some bulging and some had no signs of problem at all, they just happened to be around the same area) on the board.

After that, the TV was running like new the first night for hours. I was so excited that I fixed another electronic equipment. But then the next morning, it turned on for just several minutes and then the black screen again, again audio was ok. I switched it off and back on again, the TV would stay on for another several minutes and went dark again, no sparks, no clicking sound or anything, it just went dark. The audio is always ok.

What else could be the problem? There are other caps scattered on the board that I didn't touch, such as several 50V 0.22uF, 50V 10uF, 50V 47uF and the giantic 450V 220uF cap. Should I replace those or am I in the wrong track?

Any ideas will be greatly appreciated. Thanks a lot!

This COULD be the 'two seconds to black' scenario. Try looking at the screen from an angle while illuminating it with a bright light. If you can see the program, it's definitely an inverter or CCFL problem.

PlainBill

[rxchng]

Re: Samsung LN-S4041D Repaired... Not Quite

Could you please kindly point me in the right direction as to how to identify the inverter and what component(s) on the inverter seems to be the culprit? I googled but couldn't find much details.

My Samsung HDTV is now running smoothly for almost 20 mins now after leaving it off for about an hour. So, it doesn't appear to be the "two seconds to black" scenario, am I right?

Thanks again!!

[rxchng]

Re: Samsung LN-S4041D Repaired... Not Quite

Is the transformer on the inverter the culprit?

http://www.instructables.com/id/Tran...4_301_LCD_Bac/

[PlainBill]

Re: Samsung LN-S4041D Repaired... Not Quite

Is the transformer on the inverter the culprit?

http://www.instructables.com/id/Tran...4_301_LCD_Bac/

It COULD be. I was involved with a Philips TV (gosh, that sounds nasty ) that had symptoms similar to your TV's. But just because replacing a transformer in a Proton TV (Or a Philips) fixed it, that doesn't mean the same fix is going to work for a Samsung TV which probably doesn't use the same inverter.

FIRST establish that the image is still there, just the backlights turned off and we will continue troubleshooting.

PlainBill

[rxchng]

Re: Samsung LN-S4041D Repaired... Not Quite

After leaving the TV on for several hours, without warning, the backlights went off. Although audio is ok, the image can only be seen by using a flash light.

I attached two pictures: 1) the circuit board where the power supply is (a total of 12 caps have been replaced) and 2) the back of the TV with all other components.

Could you tell me which one is the transformer of the inverter? Is it the one behind the black plastic cover in the bottom left?

Thanks!

[PlainBill]

Re: Samsung LN-S4041D Repaired... Not Quite

After leaving the TV on for several hours, without warning, the backlights went off. Although audio is ok, the image can only be seen by using a flash light.

I attached two pictures: 1) the circuit board where the power supply is (a total of 12 caps have been replaced) and 2) the back of the TV with all other components.

Could you tell me which one is the transformer of the inverter? Is it the one behind the black plastic cover in the bottom left?

Thanks!

I'm not sure about the design, but the area under the black cover on the lower left of the first picture is a high voltage transformer. There appear to be long black covers on the left and right sides. The leads from the transformer go under the lower corner of the one on the left, and there is also a ribbon cable running back to the power supply from the upper corner of that one.

PlainBill

[Wizard]

Re: Samsung LN-S4041D Repaired... Not Quite

Hey, I once had a intermittent fault in one of small sub transformers on samsung panel, take both black covers off and put all screws back in to secure the boards.

Take a hard plastic stick and press each sub transformer firmly one by one. One will be more sensitive and panel will go dimmer (because one tube went out) and go BUZZ and shut off.

Replacing this board with transformers fixed it. Usually changed as a set.

Cheers, Wizard

[tuner55]

Re: Samsung LN-S4041D Repaired... Not Quite

My LN-S4041d sound does not always turn on, video is ok, I am not using HDMI plug but using audio out from cable to tv in and out to Theather sound, I already replaced the power supply board ( found some bad caps) but the sound still does not come on everytime. You have to cycle the tv on and off few times for it to come on.

[andocommando]

Re: Samsung LN-S4041D Repaired... Not Quite

Im having the exact same problem with the same tv. hopefully someone can lead us in the right direction

[Scenic]

Re: Samsung LN-S4041D Repaired... Not Quite

Not sure if this will help anyone, but I'll post it anyways..

edit: some Samsung LCD TVs with automatic backlight dimming (MagicBright?) had problems with just that getting glitched up..

[andocommando]

Re: Samsung LN-S4041D Repaired... Not Quite

Im not sure what that means

[andocommando]

Re: Samsung LN-S4041D Repaired... Not Quite

Any ideas?

[daveatm14]

Re: Samsung LN-S4041D Repaired... Not Quite

So my Samsung LNS5051 with a BN44-00134A power supply developed an intermittent back light issue. I have had this set for a while and had replaced some of the secondary filter caps several years ago for slow to come on. Now I find two more puffed and replace them. Worked for a week then intermittent back light out again.

On closer inspection I found two mounting grounding pins on the heat-sink for Q801 & Q802 with cold solder joints. One of the heat-sink pins is providing a ground signal to some of the circuit.

Touched up the solder joints and it is too soon to tell but I have back light back and can turn on and off.