Samsung LN52A750R1FXZA Turning on and off

[nomoresonys]

Re: Samsung LN52A750R1FXZA Turning on and off

Grab a hairdryer. Heat up the mainboard. All over it especially concentrating on the 2 processors and the various ram modules inside the white line area.

Did you try this?

[nomoresonys]

Re: Samsung LN52A750R1FXZA Turning on and off

C102 would be a lot cheaper than 35 bucks for sure.

[powerblackout]

Re: Samsung LN52A750R1FXZA Turning on and off

Would it be better to use a reflow station instead of a hair dryer? I'll check the C102 capacitor.

[budm]

Re: Samsung LN52A750R1FXZA Turning on and off

We are just trying to see if heat will have an affect on the main board operation or not at this point due to bad caps.

[freakaftr8]

Re: Samsung LN52A750R1FXZA Turning on and off

No because a reflow station would be to try to rectify the problem by reflowing the board, if there is no problem with the board there's no reason to re flow.

A hair dryer however will tell you if there is a pending problems by heating up the board just enough to get things to flex in the right direction Or bring things into close to the proper capacitance

[powerblackout]

Re: Samsung LN52A750R1FXZA Turning on and off

C102 measures 362 uf for me. My C102 is tan, not black like the other threads. Not sure if that matters. I'll try hitting the board with some heat.

[powerblackout]

Re: Samsung LN52A750R1FXZA Turning on and off

Got the two CPU's up to 220 F with no change in operation.

[freakaftr8]

Re: Samsung LN52A750R1FXZA Turning on and off

Heat up c102

[powerblackout]

Re: Samsung LN52A750R1FXZA Turning on and off

Heated up C102 as well as the back of the CPUs this time with no improvement.

[freakaftr8]

Re: Samsung LN52A750R1FXZA Turning on and off

Ok. Sense we have the heat gun out try heating up the two ICs above the main processor on the tcon board.

These problems I'm telling you to heat up, are issues I ran into before.

[nomoresonys]

Re: Samsung LN52A750R1FXZA Turning on and off

http://www.shopjimmy.com/samsung-bn9...a750r1fxza.htm found front of mainboard.

[budm]

Re: Samsung LN52A750R1FXZA Turning on and off

You may want to experiment replacing all those NEC TONKIN caps (black caps with NE u xxx) and see if that will fix the problem or not, those caps are known for failing I.E. C102 on other Samsung main boards.

[budm]

Re: Samsung LN52A750R1FXZA Turning on and off

You may want to experiment replacing all those NEC TONKIN caps (black caps with NE u xxx) and see if that will fix the problem or not, those caps are known for failing I.E. C102 on other Samsung main boards.

I did that on the LN52A650.
http://s807.photobucket.com/user/bud...?sort=3&page=1

Also
https://www.badcaps.net/forum/showth...750#post583562

[powerblackout]

Re: Samsung LN52A750R1FXZA Turning on and off

I replaced the main board and everything started working correctly.

Thanks everyone!

[vinceroger69]

Re: Samsung LN52A750R1FXZA Turning on and off

Thanks for the update.

[samanthad199500]

Re: Samsung LN52A750R1FXZA Turning on and off

What I found is that disconnecting the single cable to the tcon board allowed the tv to remain on with backlight on. The picture was obviously no connected. Initially, I unplugged the cable and placed it back on. The TV signal on the display remained stable for about 4 minutes before cycling again. Since the cost of a board is around $25, I have purchased the TCon board which is removed from a TV that had a broken screen and is verified and returns provided. Shipping is free for 1-5 day service.

My Samsung LCD TV is a LN52A750RLFXZA and the TCON board is LJ94-02346D FRCM_TCON_V0.1 the white label at the top just below the LCD screen connection contains the first numbers just after the initial letter. S2346D is the first part of the number on the label. This translate to the board part number above. If there is no zero before the number add a zero. to get the LJ94-02346D. LJ94 references the Samsung part for the LN52A750 or LN52A650 both end RLFXZA if I recall correctly.

If this does not fix the issue of a screen horizontal lines progressing to a washout image and subsequent shutting down and turning back on then I can try the cable and move back to the main board.

I tried heating the TCON board, may have overheated hit, but that did not help fix any potential solder joints as discussed in this thread.

The must be a specific reason the TV shuts off and turns back on that is in common with all the solutions mentioned in this thread. It seems that the signal from video input is amplified to a level that creates a resonance that eventually overwhelms the TCON output to the screen.

When an input signal to the TV is removed and only a setup or message is displayed, the screen seems most stable with no indication of lines or distortions. However, there has been a minor distortion on subsequent reviews without an input signal.

Also, noted that the computers stored images that are cycled were stable.

Input from another computer, DVD, or TV seemed to cause the most instability and the cycle of turning on and off.

If it is the TCON board that is sensitive to an input signal, I can see how a particular failure on the TCON board can create this common issue or a failure on the main processor can feed a signal to the TCON board that it can not handle.

The day that we had first observed the distorted screen and shutting down/on cycle is the day after our first cold weather and it was about 50 degrees in the home.

Will update on the results when I install the TCON board.

By the way, where do I get a metal shield and the conductive adhesive to cover the display cables ?

[nomoresonys]

Re: Samsung LN52A750R1FXZA Turning on and off

if you don't have the shield, it will prolly be hard to find, you can just add little heatsink/s to the necessary chips on the tcon board, doubt that you need the "conductive adhesive"