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View topic - KDL-55NX720 Problem

KDL-55NX720 Problem

This Forum is questions on any problems you could have with your Sony Televsion set (i.e. Sony Wega grainess problem, cable problems, so forth)

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by J_Palmer_Cass » Tue Nov 11, 2014 6:45 pm

I looked closely at the various service menu resets, and they all do the same thing no matter what part of the service menu that you start the reset procedure from. They are all resets to factory shipped conditions, and you must unplug the TV to complete the procedure.

The TV started to act up again a few times, so I had to repeat the reset procedure a few times. It takes longer and longer to act up the more resets that I do.

I ran the TV over night, and it was still working properly this morning. I turned the TV off, and then turned it back on after a 4 hour rest. The TV seems to be working properly for the past day. About 2 hours after a cold turn on seems to be the critical time it takes for problems to show up.

Danny at Tristate said that I should try to pickup a TCON board if I can find one. He said that new TCON boards do not exist. That seems to be the consensus of everyone I have talked to who carry the boards.

I am going to buy a used TCON board just in case I need one. I want to try a different TCON with my old BATL board just to confirm what is going on. I want to put the TV back together, but I need to make sure it is repaired before I do that.
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by J_Palmer_Cass » Tue Nov 11, 2014 7:02 pm

I forgot to mention that I tested the output voltage of the G7 LED power supply board. The voltage varies from 31 to 36 VDC as you adjust the Backlight in the main menu from MIN to MAX. The voltage did not vary with the flashing on the screen.

The backlight brightness looked steady when viewed from the rear of the screen, so the white flashing is in the video and not in the Backlight. The video freeze happened yesterday, but has not shown up again in the past 24 hours. It would take about 2 hours of run time for the skipped frames to start after a cold start, and then an eventual single frame for most of the screen. The freeze frame or white flashing has not occurred since the last reset.

I will leave the TV off overnight and see what happens tomorrow upon restart plus a few hours of evaluation time.
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by jehill » Wed Nov 12, 2014 3:10 pm

Hummm! I doubt that the TCON board is your problem. What is the part number listed on the white tag on your TCON board?
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by J_Palmer_Cass » Wed Nov 12, 2014 4:13 pm

The TCON board has the H suffix. One problem is there are no trouble codes.

When the TCON board is replaced in this TV, the service manual says that the firmware needs to be updated at the same time.


http://www.tristatemodule.com/p-19380-l ... nx720.aspx
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by jehill » Thu Nov 13, 2014 4:21 pm

I just verified that the TCON board in my KDL55XBR8 is not the same. I thought I might be able to help you.
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by J_Palmer_Cass » Thu Nov 13, 2014 6:28 pm

The TV was working for a few days, and now it just acted up again. No picture, or a fixed (non momentary) Sony startup emblem.

Looking at the flow chart, it could be the BATL board or the TCON board. It could also be the panel. I have 2 BATL boards so that does not seem to be the problem board. I have to order a used TCON board and see what happens. They go for around $50, so it is not a killer price.

The TCON on this TV drives the 3D emitter as well as the LD board, so ti is right in the middle of everything.
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KDL-55NX720_No_Video_Flow Chart.JPG
KDL-55NX720_No_Video_Flow Chart.JPG (71.52 KiB) Viewed 38436 times
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by jehill » Fri Nov 14, 2014 1:17 pm

Have you tried unplugging the LVDS connector as described in the flow chart? If not, I would.
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by J_Palmer_Cass » Fri Nov 14, 2014 4:54 pm

I am not sure if that flow chart is correct. I previously tried to unplug that LVDS cable and then turn on the TV, and all that did was produce a trouble code for the TCON as I recall.

I ordered a used TCON and will try that in the TV when I get the board.

I have the Sony Level 3 servoice manual with schematics for some of the boards, but they are not 100% accurate. At least I can check for proper power supply voltages going to different boards.

The TV is working for the moment..
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by jehill » Sat Nov 15, 2014 1:35 pm

I'll keep my fingers crossed for you. Monday I am going to my township to pay a $20 fee to have my KDL-55XBR8 picked up at the curb. It appears that no one is interested in an HD TV that is missing every third line and exhibits vertical video smearing. This is after I tried replacing the TCON, CB and FBU boards as described in my posts. When I paid over $5700 for the set nearly 6 years ago, I had high hopes that it would last at least 10 years due to the fact that it is built like a tank. Not so!

The KDL-60W850B that I bought as a replacement has provides a fantastic picture, but exhibits a problem unique to edge-lit TVs, vertical banding. It appears when the camera is panned horizontally across a white or very light colored object. I find it very annoying, but my wife doesn't notice it. I have decided to live with it for now, since I only paid $1425 for the set.
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by J_Palmer_Cass » Sat Nov 15, 2014 4:25 pm

I know what you mean. My trusty old 32" Zenith CRT TV is still plugging along,and this 3 year old Sony may be junk.

Maybe you should strip out the boards and harness/connectors in the TV and try to sell them on Ebay. Even the TV stand and remote control has sold on Ebay. The power supply and FBU board seem to be worth some money.

Maybe even ask Tristateor others if they are interested in the boards.

Here is a list of completed sales for the KDL-XBR8.

http://www.ebay.com/sch/i.html?_from=R4 ... te=1&rt=nc
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