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Old 04-26-2013, 10:05 AM   #1
tibimakai
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Default Samsung LN32C540 won't turn on

I have picked up this TV last night, so I haven't measured much.
It seems like it has a pretty common issue, but I'm not sure if it's a simple mainboard swap or there other things that I could do with it?
Basically looks completely dead and if I unplug the cable between the PS and mainboard I have backlight. If I plug it back it the backlight turns off.
Most likely the mainboard is not sending the PS_ON signal. I'm thinking of removing/cutting that wire and apply it from outside, to see what happens.
It also could be a short on the mainboard.
Any input would be appreciated.
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Old 04-26-2013, 10:40 AM   #2
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Default Re: Samsung LN32C540 won't turn on

You are correct, the main board is not sending out the PS_ON to the power supply. The newer Samsung makes it easy to find out if the power supply is good or bad by disconnecting the cable between the main and the power supply board, if the backlights come on, the inverter and the power supply is working. Samsung uses pull up resistor on the power supply board to force on the power supply, the main board keep this line low when TV is off and let the PS_ON to go high when TV is on. Check the voltage regulators and voltages on the main board.
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Old 04-26-2013, 08:44 PM   #3
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Default Re: Samsung LN32C540 won't turn on

I have pulled out the PS_ON wire from the connector and all the voltages look good, on the connector and at the VDOs. With the wire connected, there are no voltages at the connector(I have checked only one row, since I couldn't get to the second row) or VDOs.
The voltage at the PS_ON is 0.022 V only.
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Old 04-26-2013, 08:46 PM   #4
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Default Re: Samsung LN32C540 won't turn on

So when the PS_ON wire is disconnected, you should see 3V or so at the PS_ON pin of the power supply board. The PS_ON pin on the main board will about nothing.
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Old 04-26-2013, 08:51 PM   #5
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Default Re: Samsung LN32C540 won't turn on

Nothing happens even if I apply outside 3.3 V.
Sorry, I didn't understand the last sentence.
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Old 04-26-2013, 08:57 PM   #6
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Default Re: Samsung LN32C540 won't turn on

OK, when the PS_ON is disconnected, do the backlights turn on?
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Old 04-26-2013, 09:01 PM   #7
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Default Re: Samsung LN32C540 won't turn on

No. It blinks when I plug in the power cord, or when I pull the cord.
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Old 04-26-2013, 10:50 PM   #8
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Default Re: Samsung LN32C540 won't turn on

So right now main board is bad since the PS_ON stuck LOW and more likely the same for the BL_0N, the BL_0N pin on the power supply also has built-in pull up resistor, if you remove the BL_ON pin, the backlights should then turn on and stay on. If the Dimming control is PWM type, that line will have to be removed also.
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Old 04-26-2013, 11:33 PM   #9
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Default Re: Samsung LN32C540 won't turn on

Thanks. I will try both of them.
The problem is, that I can't find another board.
I read in another post that it's possible to use othe mainboards, even upgrade to a 550 model.
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Old 05-03-2013, 08:29 AM   #10
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Default Re: Samsung LN32C540 won't turn on

I ended up replacing the mainboard which I could not find.
I have used shopjimmy compatibility list, and I had only one match from a long list.
The original part number(sticker) it was BN96-14763A V1007.0 and the "new" one is BN96-14917A V1003.1.
It worked right away, but I have flashed it with the latest firmware and it's all good.
The problem is that I have spent to much on this one and won't make much money on it.
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Old 05-03-2013, 09:03 AM   #11
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Default Re: Samsung LN32C540 won't turn on

Thanks for the good news, at least you got it working and learn to figure out how to narrow down the problem to the bad board.
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Old 05-03-2013, 09:10 AM   #12
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Default Re: Samsung LN32C540 won't turn on

Lately, it's so slow the TV business and it seems that the competition is getting bigger. I have to pay more for a TV, just to be sure that I'll get them.
Need the money to change my car to a CUV, for TVs and my bad back.
I'm thinking 2014 Mazda CX-5. I have a 2008 VW Golf/Rabbit.
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Old 05-03-2013, 09:24 AM   #13
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Default Re: Samsung LN32C540 won't turn on

I no longer pick up new Samsung under 40" which have obvious main board faults (like standby LED but not turning on.) Too much chance it is the main board.
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Old 05-03-2013, 09:29 AM   #14
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Default Re: Samsung LN32C540 won't turn on

Usually I wouldn't pick up anything below 40", but when there is nothing out there, I don't have a choice.
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