Advice needed! Samsung tv

[Hamie]

Picked up a 42" Samsung with no power.
After replacing the faulty caps and a couple of resistors the tv came back to life.

However, it keeps turning off and on.
The longer it's on the faster and more frequent this happens.
So I assumed it was over heating. So started freeze spraying the caps to find out what one was causing this.
Eventually found the spot that was causing this but it turned out to be a resistor.
As long as the resistor is cold the tv stays on.

Assuming the resistor was bad I ordered a new one (without checking if it was actually bad) swapped it over and it still clicks on and off!

Now the real problem, I lent my multimeter to my dad assuming that i had located the problem and didn't need it.

I have loads of parts lying around that can be used to fix this problem but looking for advice on what one to take out first!





RS817 is the resistor that need frozen for the tv to work.

The board is BN96-03743A

Any advice will be much appreciated.

[tom66]

Re: Advice needed! Samsung tv

I'd check for cold joints in that area, should that fail consider replacing CS811 & nearby capacitors.

[Hamie]

Re: Advice needed! Samsung tv

Ok so update on this telly.
Status: still doing the same!
Don't think it's bad joints, gave the psb a good whack when it was on and it didn't turn off.
And reflowed everything around the resistor that needs chilled.

Tom you were right about that cap, it was out but still didn't fix it!
Checked all other caps around and all were good.

I have my multimeter back now, so any suggestions would be greatly appreciated.
Anyone got the schematics for this board.

Cheers

[stj]

Re: Advice needed! Samsung tv

i'd be more inclined to suspect the nearby diode or chip geting cooled at the same time.
that or the resistor is getting hot because it's connected to something that is pulling too much power.

[Hamie]

Re: Advice needed! Samsung tv

I thought the same, so I angled the spray so only the resistor was getting chilled, it's definitely just the resistor that needs cooled to stay on.
Replaced the diode next to the resistor as was slightly low, .46 if memory severs me right, but still didn't solve the problem.

The closet ic is viper22a can't find much information about it.
If all else fails I'll have to go through everything one by one, but hoping someone might have had similar issue.

[stj]

Re: Advice needed! Samsung tv

VIPer switching regulator.
made by ST
http://www.st.com/web/catalog/sense_...S1835/PF215018

[Hamie]

Re: Advice needed! Samsung tv

So it's the viper22a that's shutting the tv down.
But is it faulty or just doing it's job? How do I test this part?

If not do I conclude that it's should be a part on the left hand side of the board that maybe bad?

[martino]

Re: Advice needed! Samsung tv

pic from bottom side of board around that area? Any component there? Hairline crack in one of the traces?

[Hamie]

Re: Advice needed! Samsung tv

I'm happy to say the telly is now fixed.
it's been on for 2 hours so fingers crossed.

Incase anyone else finds a similar problem. Here's what i replaced.

Electrolytic Caps
Cs808
Cs806
Cs811
Cs404
Cm421
Cm422

Ceramic caps
Cs810
Cs813

Diode:
Ds805

Resistors:
Rs817
Rs822

Ic chip.
Ics801s

[tibimakai]

Re: Advice needed! Samsung tv

It would help even better if we knew the model number of this TV.
It's a good idea. to put it in the tile.

[Hamie]

Re: Advice needed! Samsung tv

PS42QHD

How to I edit the title?

[freakaftr8]

Re: Advice needed! Samsung tv

Nice good job on the fix!