Reply To: Replacement for a dead BV7-40

[jvezina]

Tabloka wrote:

“Hi Jean, my 7741 has also trouble with the backlight. Someday during televison the screen went black and never get back again. I sent the TV to my dealer for repairing but he couldn’t fix the problem. So I got the TV back unrepaired. I read a lot of backlight problems and also watched a lot of youtubes about this topic. In your comment it sounds that you maybe fixed a problem with the backlight by yourself. Do you have any suggestions to dismantling/disassabling the TV in order to get to the LED stribes? Meanwhile I checked most of the DC voltages of the PCBs compared to the service manual. So far I found only one DC voltage which should be 5V but it was only 3V (PCB03 P005 Pin2). Thanks in advance Michael”

Good morning Michael,

I am following this thread because  my own Beovision 7 Mark III (15 years old, now used in my bedroom) has now a backlight problem. The picture is displayed for about 30 minutes, then it starts flickering and goes black, If I just turn the TV off and on, the picture shows again for about 3 seconds and then disappears. I have to let it cool about 15 minutes. After that, I am good for another 30 minutes of viewing. I followed the “normal procedure”: I contacted my local dealer and they will schedule a visit by a technician. If the problem is caused by the backlight  and they cannot fix it, I will have to follow the procedure described in Youtube (or ask them to do it)

The service manual describes how to dismantle the TV and remove the LCD panel. But before, checking if the 24 volt supply to the inverter is present is the first step. The BV7 Mk III LCD panel uses fluorescent tubes (CCFL) for the backlight. In my own case, since he TV works for a short time, there is probably a component overheating. Using a component freezer spray to locate it would be the first step. Perhaps it is just a cold solder joint.

These TVs were expensive and top class when new and are in my opinion worth repairing.

Regards,

Jean