Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

[Geniee33]

I have a Samsung LA46S81BDX/XSA that starts up fine, its all great, but after a period of time, can be 5-10 mins, the whole screen is showing horizontal and verticle lines over it.
I have replaced the Tcon, nothing, also checked all cables put pressure on the rubbons, cant change the output.
I also put the main board through the oven for 10 mins to re-flow any solder as this has worked for me in the past.
Once its all garbled up, i can turn the tv off, and back on and it will be fine for another period of time.

Can anyone please help me?
I can get readings on output voltages and what not, but the power supply seems ok it never has issue starting nor does it make odd noises.

[Andrew F. Ali]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

Bad panel IMHO.

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

hmmm, but i dont understand why it is fine for a period of time after a restart?
I initially thought it might have been part of the heat cycles, and possibly a very fine connection problem on one of the ribbons, and the very micro heat expansion creates a short or a connection loss... but i removed the front panel/cover and while the LCD was in that state touched on all of the connectors and couldnt change the output.
Is there anything to gain by testing / getting all the PSU output voltages? although i am not hearing any relays or strange noises occuring.

[ReeceyBurger123]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

Mainboard fault, what board does it use ?

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

I will have to get the name/numbers tonight.

[Diah]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

I will have to get the name/numbers tonight.

neither mainboard.....

its voltage filter caps on power supply board issue ... only use cool spray to discover with cap make this fault.

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

oh really? I was thinking it might be worth replacing the caps just because of the cost is so low and the job is rather easy...
If i can get the voltage outputs on the power supply board in the good state and compare against the bad state, i have a theory that it may show up some differences.

[Diah]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

oh really? I was thinking it might be worth replacing the caps just because of the cost is so low and the job is rather easy...
If i can get the voltage outputs on the power supply board in the good state and compare against the bad state, i have a theory that it may show up some differences.

no this we call it noise.. out put voltage may read correct in average.. but it had absolute different Hz. this easy to know with oscilloscope. which if you want to have one will cost on your prise of 10 tv as the one now under your hand. also cool spray will be yours oscilloscope.

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

ok, i will give it a shot.
I will update the post when i have more information in the hope it helps other forum users.
thank you.

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

FYI the board is IP-301135A

[budm]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

Power supply board should be BN44-?????
This one?
http://www.shopjimmy.com/samsung-bn4...upply-unit.htm Samsung BN44-00166B
I have not seen bad power supply causing horizon lines like that. O have seen bad caps in power supply to cause this symptom as shown in attached pictures, and it will go away when lytics caps are heated up which will cause the ESR to go down and the circuit will function normally again. When lytics caps are cooled, the ESR will go up and cause problem.
You can use canned air spray upside down for cooling.

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

Yes thats correct.
I just counted and cross checked against a list of caps from an ebay ad.
Will be getting
2200uf 10v (i will get a 25v) * 2
1000uf 25v *2
1000uf 100v *1
47uf 50v *7
10uf 50v *5

They dont look bad at all, but for about $16 and an hour, cant hurt to try it out.
I wont be replacing the big 450v caps.

[budm]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

There is 1000uF 100VDC cap on that board?

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

yes, 1
located at the lower side with all the other caps "CB850"

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

Power supply board should be BN44-?????
This one?
http://www.shopjimmy.com/samsung-bn4...upply-unit.htm Samsung BN44-00166B
I have not seen bad power supply causing horizon lines like that. O have seen bad caps in power supply to cause this symptom as shown in attached pictures, and it will go away when lytics caps are heated up which will cause the ESR to go down and the circuit will function normally again. When lytics caps are cooled, the ESR will go up and cause problem.
You can use canned air spray upside down for cooling.

Yea, im kinda just *hoping* it helps.... guess for the small price, i can knock one more thing off the list.
With the cooling spray, if i spray some parts, like the caps on the main board, do i leave the tv on and see if it starts working again? or whats the procedure?

[budm]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

yes, 1
located at the lower side with all the other caps "CB850"

Hmm, the schematic for the REV C board shows the cap as 1000uF 10VDC used for the 5.2VDC power supply filter.

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

yes, sorry my mistake.... it was very small text and i read the cap wrong.
it is a 1000uf 10v.
thanks, you saved me another trip to the store

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins


replaced all the caps on the power board, (except the big mofo 450v ones) ... started up fine, after 5 mins, back to junk.
Turn off
Turn on
Working for another 2-3 mins, then garbage.
I also tried switching sources to analog TV thinking maybe it was the digital tuner, but nah still junk.

[Geniee33]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

hmmm, whats interesting is, while i was trying to cool the back with a fan... LOL (no freeze spray on me)
I removed 1 of the 2 tcon board ribbon cables, half the screen went white, but the other half came back to a normal picture.
I put it back in, went junk again, wiggled it, nothing.
Removed the other side, still junk.
So i think it might be that ribbon cable... because even tho putting pressure on it does nothing, i finally got it just plugged in in a way that the picture was fine on both sides for a good 10 mins.
I also have tried replacing the tcon board on that set, so i am sure the board itself is ok.
Are those ribbons replaceable? they are short and i remember connect to the circuits on top of the tv before then going into the panel
see pics.

[budm]

Re: Samsung LA46S81BDX/XSA - Lines after 5 mins, restart... fine for another 5 mins

That is bad panel, more likely the TFT driver ICs (they run hot) that when they get hot and cause the problem you see on the screen.