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Sony KDL-60NX720 Failed after 1 1/2 years! 4 LED Blinks

post #1 of 19
Thread Starter 
I've got the KDL-60NX720 that has now failed. When I power up, the screen comes on, led goes green, then after about 3-4 seconds the screen shuts down and I get 4 red led blinks. The "helpful" tech at Sony support says I need to bring it to a repair facility because the code is a failed board or screen problem. (Wow, that was helpful). Searching around I've found some sites say the 4 blinks is related to the backlight.

I am fully capable of fixing this myself once I find the problem (even to the extent of replacing hi-density SMD's). If anyone can provide any information as to the real failure and the fix, that would be appreciated. I'm sure I'm not the only one with this issue.

I've searched the net for a service manual but cannot find one for this set. If anyone knows of a source for the service manual, please post.

Thank you!!
post #2 of 19
FWIW, frequently, the 4 blink code for Sony indicates a BAL failure (e.g. main board).

post #3 of 19
Thread Starter 
Hi, thank you for your reply. I've see a number of different code tables for Sony's. Do you know if that one is specifically for my Bravia set? Also, is the "balancer" the name for the inverter board for the LED's?
Edited by firemanbob - 1/12/13 at 10:33am
post #4 of 19
That screen shoot was for KLD EX series service manual, which is why I said the 4 blinks are 'typically' failure of the main board.

Have many sources for repair manuals, but after a quick search, did not find one for your KDL-60NX720.

I'm a retired electronics engineer and before formal schooling, helped my uncle, who had a TV repair business.

Back then, the way TVs were made, you isolated a failure and replaced a vacuum tube or if necessary, to an individual component (e.g. resistor, capacitor etc.).

At this point, from what you have said, I would suspect a failure with either the power supply or main board.

There is a section of the power supply that is always on e.g. 7x24), and since you're getting the Sony SOS signals, it is operational.

It powers the remote control input circuitry and the processor on the main board.

When the' power on signal ' is received, the main board sends a voltage level to the power supply, for it to turn on the rest of it's circuity and power the rest of the TV.

I would check the voltage outputs on the power board (usually silk screened on the board) and , if absent, that the main board is sending the correct turn on voltage level.
post #5 of 19
Thread Starter 
I a little confused by the terminology regarding the boards. So far we've got the balancer, main board and power supply.
When I open the set back, I see a main power supply on the left. I checked the marked voltages coming from this board and they all appear to be correct (standby 3.3, 12 and operational 12).
This board feeds another power supply board (what I'll call the LED power supply) in the upper center of the back that appears to be the LED power supply judging by the silkscreen for the connector pins (LED Vcc, LED Gnd on multiple connector pins). Looks like this board takes AC from the main power supply, has an on-board switcher with dual planar transformers that feed an output section that has a good number of power resistors and electrolytic caps in parallel. The output from what appears to be the + and - rails on this board go to a connector with multiple shared pins labelled LED Vcc and LED Gnd, along with LED Err. That connector feeds another board (which I'll call the LED driver) in the center of the back that has 5 small ribbon cables going into the LED array. There's another ribbon cable going to another board just below it..
What I've done so far, in addition to checking the voltages coming out of the main board is:
1) Monitored the LED Vcc and LED Gnd while powering up on the LED power supply board. This voltage goes up to about 35vdc then drops when the screen shuts down.(Chicken or the egg?)
2) Disconnected the LED array from the LED Driver board and monitored the LED Vcc and LED Gnd on the LED power supply. With the panel disconnected, I get about 55vdc before it shuts down.
3) Disconnected the LED Driver board completely. Get the same result on LED Vcc as above in 2 on the LED power supply.
4) Connect each LED ribbon cable on the LED Driver board one by one and monitor the LED Vcc. In each case the voltage comes up to about 35vdc before the set shuts down.
5) I've taken the LED power supply and LED driver out and inspected for burnt/open/shorts/damage. They both look fine. The fuses on both boards are ok.
There's no marking on the LED driver board or 2nd power supply as to what the voltage should be. I can't isolate to either the power supply or the driver board since without the driver the supply gets to 55vdc. With the driver board connected, all the LED's come on for a few seconds.
I guess I would have expected the set to stay on if I removed the board that was causing the problem.
So what exactly is the "balancer" board?
Any ideas would be helpful. Thank you.
Edited by firemanbob - 1/12/13 at 6:24pm
post #6 of 19
Thread Starter 
Ok, so moving right along here, I've been able to get the set up and running by disabling the BL_ERROR signal from the main ps to the controller. I now get a picture but what I see is a dark area in the lower right of the screen. I guess the LED edge/backlight is indeed bad and not the electronics.

HOW THE HELL CAN SONY SELL THIS CRAP! 1 1/2 year old set and the LED backlight is bad and warranty is expired! WTF!

The general belief in the industry is newer is better so since LED's are new, they must be better. What a bunch of crap! I have an LG LCD with ccfl that's 5-7 years old and running strong. Since this set is no longer under warranty, Sony can go to hell. But here in the USA, if they were to even mention that they were going anywhere, I'm sure the hand-out administration would fork over a few hundred million to "bail" them out. Guess this is their way of getting us back for the bombs.
post #7 of 19
Glad to hear that you made some progress.

I was hoping to help further and come up with the service manual for you set, but only found service manuals for the EX, HX series and a MX800.

You mentioned 2 power boards and shopjimmy indicates that there is a G6 (e.g. primary power board) and G7 (e.g. secondary power board), which seems to power the edge LED modules.

Are you going to look into the second power board further?
post #8 of 19
Thread Starter 
I tried swapping the ribbon cables from the LED driver (G7) (there's 5 identical cables that go to the screen) to see if the dark area followed the board or stayed in the same place. When I moved the cables, I was not able to get the backlight to come on at all. Without the schematic for this board, I'm shooting in the dark. I would like to try and isolate the problem to find out if it is indeed the G7 board. That would be an easy fix. Not sure if it's possible to fix it if it's the LED array in the screen. I took a look last night at removing the trim around the screen and the screen assembly appears to be one unit encased in a metal frame. I was hoping I could get to the offending LED section and do something to test it.
Do you know how this edge LED array is assembled in the screen and if it's possible to just remove that part of it? Also, any ideas on trying to isolate between the G7 and the LED array?
Thank you.
post #9 of 19
While I did not find a service manual for your specific model, you may get some insight to your questions from looking at service manuals of similar Sony models.

I've been able to find service manuals for just about every TV I've repaired at:


The above site is a treasure chest of service manuals and as a guest, you can download 2 free manuals / day. If you can answer 5 questions in electronics, you can download an unlimited number. Just type in a few key words, select TV and type of document your looking for. Most files are in .pdf format (a few are zipped or DJVU files), so as long as you have a .pfd reader (e.g. Adobe), you don't need to download any additional software. After you select a manual (e.g. click on the blue arrow), you'll see a page to 'Get Manual'.

Alternatively you can try here.

post #10 of 19
Thread Starter 
Ok, thanks. I'll have a look. Hopefully I can find another set that uses the G6 and G7 boards for LED drivers.
post #11 of 19
Thread Starter 
I got my registration from the test for that site. Correction on the boards, it's the YL board that I think is bad (ST4055YL-S01).
I could not find the schematic with the chassis for this set.
post #12 of 19
Hey wondering how you went with your Sony TV? any progress or fixed?

I've got a KDL-55HX820 and sounds exactly like same problem:

powers up, starts up, displays screen then turns of after 5 sec, (top screen appears slight darker and at the bottom only in middle)
RED power light blinks 4 times.

4 times-Malfunction of 5V line (Voltage Supply to FE, etc)

The 55hx820 got the same components inside as yours G6 and G7 and YL Board (LED Driver),
Also I could not find a service manual for my model but found KDL-46/55HX920
post #13 of 19
post #14 of 19
Hello we have the same issue on a Sony KDL-55EX720, also is 18 months old.

We have a Sony KDL-55EX720. When the TV is turned on, it display the screen for few seconds and them it automatically Turn Off and give a signal of 4 red light blinks. This is suppose to be a backlight inverter failure. We requested Sony Part 147430211 (DPS-78 CH 1-883-933-11) G8 Converter/inverter and replaced it, But the TV Still give the same message. What can you recommend us to do?
post #15 of 19

Hi Firemanbob...  Just curious if you have ever found a solution to your problem with this set.  I have the KDL-55NX720 and have the exact same issue you've had with the 60.   Have been reading your post on many forums concerning the issue, but haven't seen that you've had any luck.



post #16 of 19

Thread just stopped?  What's up with this problem of 4 blink death.  No fix ever?

post #17 of 19

Hi! Recommend to replace the power LED-drivers ST4055YL-S01 or find and replace a defective chip on the block BD9276EFL.

post #18 of 19

Hello All I'm new here and felt the need to share this info:


I read through many manuals and many voltage checks to find this (temporary quick fix) for the 4 blink error on these NX models


As we know the 4 blinks comes from being a BALANCER issue determined by voltage protection checks through the BL_ERROR signal wire/s


I have found that on a good working set the BL_ERROR signal wire should read low/ 0V


so to simulate that I simply just grounded the BL_ERROR signal wire off of the connector cable on the G7 board or secondary power supply that powers the LD board


With that I was able to make the unit come on and stay on which allowed me to see the failing section of LEDs from the panel.


Again I will say this is a temp fix solely because im more than sure that because of the failing LEDs within the panel, the voltage output coming from that board is not distributed evenly thus possibly having over voltage which can lead to eventual failure of the secondary power supply or LD BOARD... But thats just my take on it.... and also from what ive read from others with similar sets and circumstances using these "round about" solutions ;)


I'm just sharing and confirming this method does work and I hope this helps others in troubleshooting their panel problems :)




Goodluck all Signing off...

post #19 of 19

Thankyou hipnotech83 for the update.  Many people may be depending on this thread in the future years,


I've had a 46hx820 fail (4 blinks) within the last week of year warranty and sony replace it with a 55w900a.  Still have in household 1 46nx720, 1 46hx820, and 2 55hs820 - all out of warranty.  So I will be following this column indefinitely.  Many thanks!

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