TV will not power up
I've replaced all three boards, the power supply, the main and the T-Con boards. The TV still will not power up
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Hi @mikeb83239
The following is based on that the Power board is a BN44-00716A as this is what shows up most when searching for a Samsung UN60H7150 power board.
Here's an image of the power board that shows the Standby voltage reference point on the power board.
When power is connected to the TV the power board applies an 8V DC signal to the mainboard and it is the mainboard that turns on the Standby power LED in the bezel - with the power connected to the TV, use a Voltmeter and check if there is 8V DC on the reference link.
(click on image)
If it tests OK another test that you can do is to disconnect the power to the TV and then unplug the mainboard - power board cable at the power board end and then reconnect the power to the TV. The TV screen backlights should turn on and stay on. There will be no picture as the mainboard is disconnected. Note: I'm not 100% sure that this test will work on your model or not. Hopefully it will.
If the tests above work then its looking like the power board is OK and it may be the mainboard or the cable between the mainboard and the power board perhaps
Use the Ohmmeter and check each of the mainboard- power board cable wires for continuity from end to end. Do this with the cable disconnected at both ends.
Be safety aware when testing on the power board with the power connected. There is exposed lethal AC voltage on the board
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Great troubleshoot tips. Sadly with both the Main and T-Con boards disconnected, the power board unloaded the StBy voltage is 1.6vdc, with it plugged in the StBy voltage drops to 1.4 vdc. All 3 cards are new which leads me to think that the power card blew as soon as it was powered up. This leads me to think that the LED array has a short. Thoughts?
There should have been 13V DC on the Standby ref point when only the mainboard cable was disconnected as the power board has been effectively told to "turn on" and supply full power to the TV.
With everything connected there should be 8V DC on the Standby ref point.
Maybe try disconnecting only the LED backlight cable and then check what voltage is there.
What was the sequence of the board replacements?
First scenario is if you initially only replaced the power board, then perhaps if there was a problem on the mainboard for example, then this may have caused the new power board to fail as soon as the power was connected.
After doing this when it still didn't work you then replaced the mainboard because unbeknownst to you the new power board had become faulty and so on.
Second scenario is if you replaced all 3 boards at the same time - then it may be something associated with the LED backlighting or the panel or even the button control board.
You can buy TV LED testers online (examples only), that allow you to test the backlights in isolation i.e. no power connected to the TV. You disconnect the backlight cable from the board and connect the tester directly to the cable. It supplies the power to turn on all of the backlights or not if they're faulty.
With only the main board disconnected there was only 1.6vdc at the Stby test point, with all boards connected there is 1.4vdc. The sequence of replacement was the power board first, then the main board followed by the T-Conn board. I agree that it's possible that there was an issue with the main board which could have caused the power board to fail immediately. If so the power board didn't fail the same way since the failed component drew enough current to burn through the PC board. I'll pick up a TV LED Tester and verify the LED arrays are good before I replace the power board again.
What are the odds that the new main board is damaged with the newly failed power board?
Hard to say.
Was the TV on at the time it originally failed or was there a power outage or storm at the time?
If the LED backlights test OK then hopefully the new main board is still OK.
If you try a new power board, install it but without connecting the other boards maybe just the backlights. Then test for the Standby voltage.
Again not sure re your model but it shouldn't harm the power board doing this.
If it tests OK then connect the mainboard and tcon and check- remember to disconnect power before connecting/disconnecting cables.
Is the tcon connected to the power board as well or only to the mainboard and screen?
Tested the LED strips, they were good. Replaced the failed (2nd) power supply board and the main board and powered up the TV and all is well. Picture looks great. Thanks for all the help. mike
2 Comments
Hi @mikeb83239,
What is the model number of the TV?
Is the TV's red power standby LED on or off?
If it is off have you checked that the wall power outlet is working?
If it is on, have you tried using both the TV remote control unit and the TV control buttons to see if the TV turns on?
Asking because all you mentioned was that you changed all the boards so we don't know what else you've tried.
Do you have a DMM (digital multimeter) and know how to use it?
by jayeff
The TV is a Samsung UN60H7150.
There is no indication of power at all, although I do have power on the power supply board, checked with a DVM. Without a schematic or O-scope I have no way of diagnosing it further.
Yes, the wall power is good. Obvious to check but always worth asking.
I have tried both the remote and the TV control buttons, still no power indication.
Some background. The TV failed to power on. Turns out the power supply board was fried, I mean really fried, with a hold burnt through, which is not uncommon. After replacing the power supply board still no power so I replaced both the Main and the T-Con boards. I still have no power indications, no bezel standby light, nothing. I'm very perplexed.
Thanks for the input, mike b
by MIke B