Re: Samsung UE55H7080 black screen (sound is working)
OK. If that is the pin you are looking for, it means that the motherboard gives the command to backlight. The command follows a route and arrives at the LED driver. Measure if that command arrives and if something is not interrupted.
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Re: Samsung UE55H7080 black screen (sound is working)
Like I said, I don't have any connection to satellite or similar on my measurement place. BLU_ON raises from 0V when the TV is off to 4.6V when I switch the TV on.Leave a comment:
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Re: Samsung UE55H7080 black screen (sound is working)
I think BLU is the command for backlight ignition. With the TV in the socket, measure the voltage there (theoretically + 3v approx.). Press power on and see what voltage it looks like (theoretically 0v).Last edited by yokoono; 05-11-2019, 08:56 AM.Leave a comment:
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Re: Samsung UE55H7080 black screen (sound is working)
Sorry for asking so much but where is the bl_on located? I only find BLU_ON on the power supply board (on the right hand side).
The voltage at the wire which is labeled with STB and ON changes from 0 to 12.63V when I switch the TV on.
I have to note, that every external connection to my TV is disconnected, only the power is available at the station where I measure stuff.Attached FilesLast edited by Steradiant; 05-11-2019, 08:37 AM.Leave a comment:
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Re: Samsung UE55H7080 black screen (sound is working)
The motherboard does not command backlighting. Measure if there is voltage on the BL-ON pin when turning on the TV.
Theoretically when it is in stb on bl / on it must be + 3v approx. and start at 0.Last edited by yokoono; 05-11-2019, 07:47 AM.Leave a comment:
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Re: Samsung UE55H7080 black screen (sound is working)
Unplug this connector to see if backlights turn on.Attached FilesLeave a comment:
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Re: Samsung UE55H7080 black screen (sound is working)
Disconnect the connector between the motherboard and the source. The backlight must light up. If not most likely you have broken LEDs. With a stronger light, you can also see if it is an image.Leave a comment:
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Samsung UE55H7080 black screen (sound is working)
Hello,
some days ago my Samsung UE55H7080 broke. When I switched on the TV, the screen stayed black (2 hours ago I was still watching TV). The sound is still working, I can hear how I can switch channels, go into the menu and so on. I've already tried to plug the TV off for the whole night and plug it back on the next day and it didn't help.
I decided to open the TV because I thought it might be a problem with the power supply for the backlight. Attached you can find some pictures of the inside of the TV.
What I've already checked:
- The fuse on the supply board is ok
- I can't see any broken wires, bulged capacitors or similar.
- I've checked the voltages of the LED supply; they are as follows
CNL801A:
Pin 1 (N.C.) 0V
Pin 2 (N.C.) 0V
Pin 3 (L4+) 16.8V
Pin 4 (L4-) 0V
Pin 5 (L3+) 54.7V
Pin 6 (L3-) 0V
Pin 7 (L2+) 54.7V
Pin 8 (L2-) 0V
Pin 9 (L1+) 16.9V
Pin10 (L1-) 0V
CNL801B:
Pin 1 (N.C.) 0V
Pin 2 (R1+) 39.8V
Pin 3 (R1-) 16.9V
Pin 4 (R2+) 127.4V
Pin 5 (R2-) 54.7V
Pin 6 (R3+) 127.4V
Pin 7 (R3-) 54.7V
Pin 8 (R4+) 39.8V
Pin 9 (R4-) 16.8V
Pin 10 (N.C) 0V
What makes me wonder a little bit when looking at those voltage levels is, that they are not the same for left and right but I sadly haven't found a circuit diagram of the BN44-00715A in http://www.toms-service-manuals.com/ or elsewhere.
I also can't see any light coming through the tiny holes in the back of the tv when I plug it in and switch it on. I haven't tried that in the very dark yet though.
Do you have any suggestions what to check further? Mainly it would be interesting for me, where the failure is. If it is "only" the backlight or the screen.
Thanks in advance.Attached Files -
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