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Shahid, Technician
Category: TV
Satisfied Customers: 9368
Experience:  I have been repairing electronic gear since 1993 as a qualified Sony tech
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Sony KDL-46XBR9 Power Issue. Looking "TV Expert" .

Customer Question

Sony KDL-46XBR9 Power Issue. Looking for a "TV Expert" for help. Please note that my question was submitted once already but it is my opinion that the wrong expert attempted to answer so I am going to try one more time. In lieu of going into all of the details I am attaching a link to my original question and correspondence that I had with the first expert.
Please let me know if you need any additional information or if the link is incorrect. Thanks.
Submitted: 5 months ago.
Category: TV
Expert:  Shahid replied 5 months ago.
Hello and Welcome. My name is ***** ***** I'll assist you today. I'm sorry you're having trouble with it. I need additional info to troubleshoot the issue.- Does TV still turn On normally with back cover removed?- What does the power light do when TV refuse to turn On, does power light blink in specific pattern?Thanks.
Customer: replied 5 months ago.
Thanks for the quick reply. TV is doing the same thing it did when the problem originally started. Pressing the power button would make the power light come on for about 3-5 seconds, no blinking, you would hear a click (relay) and then the light would go out. I believe I could do this three times and then nothing, no light. I could unplug the TV and then could repeat the process. The TV did nothing else, no lights, sounds, etc. I had a local Sony repair shop diagnose as far they could without fixing and they thought it was the main power board. I purchased and replaced the power board. After installing and prior to re-installing the back cover, I plugged the TV in and the back light did come on. I only left it on for a few seconds though. I unplugged the TV, re-installed back cover and then set it up with the power and cable connected to verify everything was working, picture, etc. The back light did not come on this time and it started doing the same thing again. Power light for a few seconds, the relay would click and then power light would turn off.
Expert:  Shahid replied 5 months ago.
Thanks for detailed reply, power indicator light status/ response is very important in troubleshooting process and I need to know does the power light turn to red and flash when TV doesn't turn On/ you get 2nd click of relay.In Sony TVs, power light flashing in specific pattern like 5 blinks, pauses for 3 seconds and again blinks 5 times etc is an error code that helps to figure out problem section in TV.So please check and focus on power indicator light only and ignore the relay clicks sound for a while, press Power button and check power light what does it do.
Customer: replied 5 months ago.
Sorry for slow reply, atypical past couple of days. I had to reinstall main board, which only took a minute, as I wanted to make sure my answers were detailed and accurate. After I installed the main board I plugged in the power cord and heard one click. I did not press power button prior to this first click. Relay had closed. I then pressed the power button, no click and power light came on (solid, no blinking) for approximately 9-10 seconds followed by a click (relay opened) and then power light turned off. I pressed power button a second time, heard an immediate click (relay closed), power light came on (solid, no blinking), for two seconds at which time I heard a second click (relay opened) and power light turned off. I can't remember if I could repeat this process for a third time but I could do this either two or three times and then nothing would happen when I pressed the power button. I could unplug the TV for a few seconds, plug back in and then it would repeat the entire process mentioned above. The power light was always solid, no blinking. I hope this answers your questions.
Expert:  Shahid replied 5 months ago.
Thanks for detailed info. There are two questions come into my mind which will help me to troubleshoot the issue.- Does screen glow/ show backlight when TV turns On for short time?- What circuit board(s) you have already been replaced in TV so far?
Customer: replied 5 months ago.
The backlight does not come on. The TV does nothing else.
I replaced the main power board (G7N). Please refer back to my first reply above dated "20 May 2016 12:44" in regards ***** ***** coming on after I replaced the power board.
The "main board" that I referenced earlier today and had to reinstall was the "BU" board. I had removed it to inspect for any signs of damage.
Were you able to pull up the link to my 1st question with the other expert? It may have been a bit too much to read and follow. No big deal either way. If you need any more information or need me to look at something please do not hesitate to ask.
Expert:  Shahid replied 5 months ago.
Thanks for the info, I have gone through your previous post as well.TV symptoms indicate BU Board internal failure and not necessarily the burnt parts are visible on board because they work on low volts and lots of processor chips/ ICs are mounted on BU board that can cause the issue. Did you replace BU Board?If not yet, please go ahead and replace it in TV which will help to resolve the issue. Please reply back with the result and if problem resolved then a positive rating to answer would be highly appreciated.
Customer: replied 5 months ago.
BU was not replaced and I am hesitant to replace as I am now concerned the new power board was damaged and will need to be replaced as well. Can the BU board damage the power board? As previously stated, when I installed the new power board several weeks ago the backlight did come on but I only left it on for a few seconds before turning off TV, unplugging and reinstalling back cover. When I went to test TV with power and cable connected the backlight did not come and TV was back to doing the same thing as detailed in my previous replies. After this happened I took everything apart again, removed the power board and looked for signs of damage. I did not see anything but I am not an expert. I reinstalled the new main power board but the backlight did not come on this time. I had hoped there was some sort of reset that would occur if I disconnected it from everything but this does not appear to be the case as the backlight did come on this time. Did the new power board get fried somehow? Due to cost I am not sure it is worth buying a used BU board and another power board. Your last response states that I need to replace the BU Board and that this "will help to resolve the issue"? Did you mean to include the words "help to"? "This will resolve the issue" sounds much better. I am to the point now where if I replace the BU board I will be at the max of what I was willing to spend on repairs vs. buying a new TV. The BU board will be used which is another gamble. I have not seen any new BU Boards available and if they were the cost would be to high to justify. Right now I have spent $50 for a local Authorized Sony repair to diagnose, $25 for power board plus $28 if I include Justanswer = $103. A used BU will probably cost $75-100 unless you know of somewhere I can get cheaper. This would put me at approximately $203. If the new power board has to be replaced again that will add $25 = $228. Spending $100 would have been clearly worth it but I am not sure about $228 when you factor in a "used" BU Board as you don't know how long it will last. Are you 100% sure that replacing the BU Board will fix the TV? Will I need to purchase another main power board? Is there anything else I can check? Thanks.
Expert:  Shahid replied 5 months ago.
Power board of TV wasn't/ isn't bad as it works and BU board is main processor board that controls all the functions of TV including power on-off, backlight control, menu option controls, video audio signal processing etc.If power board was/is bad then TV will not stay On and switches off with specific pattern of flashing power light (error code) and same will happen if backlight system has failed.This TV has self diagnostic feature that can check power board, backlight inverter board, audio section problems and present the error code by flashing power light, all this diagnostic circuitry is build on main board that works with main controller chip, now if main controller chip has failed then TV will act as you're TV is doing so that is why I diagnose the BU board is bad and causing the problem. You can return unnecessary boards later to suppliers once get the TV up and running.I hope these info will help to make decision about this TV repair or invest the repair money on new TV. Please feel free to respond if you have any additional questions.Thanks.