LN46a500T1FXZAA with seeming broken power board

[Vowswithin]

Hi guys, my TV has been doing the turn on off thing when I go to boot it up. Can here it clicking and I get display eventually but it's messed up for about many tries and eventually I get a working picture. Some times it comes up fine and soon as I try using the remote it reboots others I get scramble or discoloured picture... Thought it was the main board but replaced it and it still is doing the same thing. Looked at the caps none are leaking or bulged. I was thinking maybe I should test the power section before buying new caps and not fixing the problem?

Power board is the ip-271135a aka the bn44-00202a how would I go about that exactly?

[budm]

Re: LN46a500T1FXZAA with seeming broken power board

Post good clear pictures of the boards and the whole back of the TV so we can see how the boards are connected will be a good start.

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

Back of TV

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

Power board

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

Caps

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

Main board

[audiofreak19]

Re: LN46a500T1FXZAA with seeming broken power board

I bet tv's gonna be a fault in the t con board. The board that's under the metal piece at the top of the tv. With it shutting off and on the main could be sensing a fault and with the picture being scrambled or messed up could be the fault the main board is sensing and very rarely could be making the correct connection. Just my guess from what you have said so far.

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

I bet tv's gonna be a fault in the t con board. The board that's under the metal piece at the top of the tv. With it shutting off and on the main could be sensing a fault and with the picture being scrambled or messed up could be the fault the main board is sensing and very rarely could be making the correct connection. Just my guess from what you have said so far.

Is there a way to test it then?

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

Anyone ?? Not sure how to
Proceed with testing here either the power board
Or the t con

[johnboy1313]

Re: LN46a500T1FXZAA with seeming broken power board

Unplug the T-con. If the set powers on, then plug the t-con back in and disconnect the panel from the t-con. If the set still powers on then your screen probably has a short and isn't fixable. If the set won't power on, then it's probably your t-con. If the set won't power on with the T-con disconnected and the panel disconnected, we'll look elsewhere.

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

So I unplugged the tcon and the set is still powering on and off like it would do before.

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

Any thoughts?

[Vowswithin]

Re: LN46a500T1FXZAA with seeming broken power board

Unplug the T-con. If the set powers on, then plug the t-con back in and disconnect the panel from the t-con. If the set still powers on then your screen probably has a short and isn't fixable. If the set won't power on, then it's probably your t-con. If the set won't power on with the T-con disconnected and the panel disconnected, we'll look elsewhere.

its been a long time but this tv is still sitting in my basement.

I just tried it and same thing, no tcon plugged in and it is clicking away still.

[dick_barton]

Re: LN46a500T1FXZAA with seeming broken power board

Why don't you start by measuring the voltages on the connector CN801 and the one above it and give the readings. This may help to solve your problem.

Connector xxx
Pin1 PS_On = xx volts
Pin2 Sync = yy volts
etc


Do the backlights come on when you disconnect the mainboard and power up?

[Unspun01]

Re: LN46a500T1FXZAA with seeming broken power board

Hi Vowswithin:

Unless the power supply has visibly bulging capacitors in the secondary circuit, this does not sound like a power supply issue.

From your initial description, this sounds like a mainboard issue common to A-series Samsung LCD and plasma TVs.

You state that you had resets, and glitchy video, perhaps also accompanied with audio screeching?

You also state that you replaced the existing mainboard with a different mainboard. I suspect that both mainboards may have the same issue.

I think you need to replace C102 and C131 on mainboard, adjacent to white 24pin connector.

Both caps are polarized surface mount caps. C131 is on the top and C102 is on the bottom. Marking C131 easy to spot. Marking C102 may be difficult to find, but capacitor should be next to IC101.

Measure the voltage across the capacitors before removing the capacitors. They have a polarity marking, but it is opposite to what you think. The band indicates positive which is not consistent with other can type electrolytic capacitors. Installing electrolytic capacitors backwards by accident may cause them to blow up.

I think I used 47uF/50V caps.

See this thread for more information:

https://www.badcaps.net/forum/showth...ight=C102+C131

Also, you may not need to remove the bad capacitors C102 and C131. In my TV, it was sufficient to solder the new capacitors across the existing ones, and even makes it easier not to damage solder traces if you are not a good at soldering. NOTE THE CORRECT POLARITY!!

[nomoresonys]

Re: LN46a500T1FXZAA with seeming broken power board

Maybe check DB803 and all the rest of the diodes.