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.
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.
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.
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.
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?
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?
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.
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.
AUSTRALIAN KDL BLINK CODES :
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
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?
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.
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...
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!
I have a 55Hx820 and it had the 4 blink error.
As per above the BL_ERROR signal can be earthed and the TV will then work. Our backlight led problem was intermiitent, top and bottom RHS of the screen, it worked about once every 20 times it was turned on if you were very lucky.
Hence its either a faulty panel or faulty Led Driver. Having an electronic background my money was on the led driver, particularly as it is intermittent on our TV.
Bought one from ShopJimmy and it now works as new :)
Sony (Australia) don't supply this as a spare part, it is part of the panel (service manual says not available), which explains why the 4 blink error 'usually' requires a new panel - I wonder how many TVs have been trashed when all that was required is the led driver PCB.
I have a 6 blink count, and the tv turns on but has a dark area where the LEDs don't turn on. (6 blinks on the diag menu refers to "Backlite")
I have ordered a new (Samsung manufct LED Driver) as sold on Shop Jimmy but also on sale on Ebay for $10.
While I wait for the part can someone advise me how to prevent the tv from doing a shut down? something about grounding the ER Cable?
I don't know what that means, I don't want to cut the ribbon cables that feed the different boards as I may need to reconnect them in the future?
The method I wrote above is simply for troubleshooting purposes if your repair extends further than the LD_board being replaced. It was not intended as a solution its more of a quick fix for troubleshooting... in my case on my 55NX720 the technical writeup for the television was correct, it was a PANEL issue (Backlight starts then cuts of into 4 blinks).
As far as explaining the method... I no longer have the television anymore so I cant take any pictures sorry, I will say its pretty simple. Look at your boards, there are wire tables printed on the board telling you which wire is the BL_ERROR wire. I did not cut any wires so you shouldn't have to either... the connector the wire is on is plastic. If you look close enough the wire is held in place by a small clip... use a razor blade to lift the clip up and pull the wire out... its that simple then ground the wire anywhere and that will bypass the 4 blink error...
Remember you do this at your own risk I am not liable or responsible and neither is this Forum. If you have warranty and even if that warranty is off by a month Try calling sony for the replacement. Be patient and persistent and good luck.
I replaced the LED Driver with no change/improvement,
The TV turns on and looks fine, but auto powers down within 1 minute.
so my diagnosis is a bad LED strand (with 1 bulb out) that is sending an error and shutdown signal.
I understand grounding the error cable is not a supported option and has risks, but I would like to do this until I can afford a new tv. (as the 1 LED that is out, really doesn't ruin the viewing experience)
Anyway, I see 2 tables on the the Sony G9B Power Board.
Image of G9B Power Board
The table that directly links to the LED Inverter/Driver Board has the following:
The closest I see is GL-ERR in the #1 Pin location.
I do not see any BL-ERROR text on the power board.
I taped the aforementioned GL-ERR wire to the metal frame of the tv, but still get the same power down and 6 Blink Code.
Last edited by AMRivlin; 06-22-2014 at 01:55 PM.
The parts I am looking for come from a Sony KDL-40NX711
I need 1 strand of LEDs. Shopjimmy and ebay were not useful in my search.
3 codes are printed on the bar of 63 LEDs
KM-8 94V-0 1028
On the back a barcode with
The Bracket the LEDs is attached to is labeled
D001005A0 40-UP LJ64-02635A
This edge light assy linked below *might work * what you have there is a Samsung 40" LED edge light panel
lots of other TVs use Samsung panels try posting the panel sticker # here and also seach that part # we can also look it up at panlelook.com and see if Sony bought it with or without the backlight FWIW I think they bought it complete on yours though . The lamp below is out of a 120 Hz Samsung 1080p panel in a SEIKI TV and *might work if it fits*
Yours looks like a tough one to find so far. Your exact part # is as you corectly assumed
This is the panel out of the Seki 40" the linked Ebay lamp came from a decent 450cd/m2 5000:1 cr 120 Hz 10 bit panel . used in several other sets including Mitsubishi and Toshiba
There should be a 40" Samsung panel light bar assy somewhere if this doesn't fit( it might? ) Your light assy is probably in ~a Million 40" sets and not necessarily unique to Sony or there is always the waiting game on E pay good luck .
Edge lamp Link
Last edited by tubetwister; 06-27-2014 at 03:58 AM.
Here are 2 photos:
$10+24 shipping. I can live with that. Was expecting to pay over $100.
Now I just have to hope i can reassemble the tv from memory.
|Sony Bravia Kdl55nx720 55 Inch 1080p 3d Led Hdtv|