Sony KDL-46EX700 - No Screen

[drpj23]

Ok so I have this sony and it does power on (red to solid green) but there is no display.

I have found there is no voltage for the backlight completely and the T-CON but there is voltage otherwise on the powersupply.

Now, I know y'all love pics but I can't get to it till prob Monday or so but maybe if someone has had this prob they could help me test or diagnose.

So far my my thoughts are either in the power supply but more towards the main board.

I know this description is really in the dark but I will get more info for you on Monday such as the pics and voltages on each pin.

Thanks

[killian6pk]

Re: Sony KDL-46EX700 - No Screen

Check all the connectors for proper voltages. They each should be labeled as to which pin has what voltage. Be careful (don't short pins) use a screw on each board for ground. Make a list with the connector label and then each pin with what it is supposed to be and what it actually is.

[Sonylistens]

Re: Sony KDL-46EX700 - No Screen

Ok so I have this sony and it does power on (red to solid green) but there is no display.

I have found there is no voltage for the backlight completely and the T-CON but there is voltage otherwise on the powersupply.

Now, I know y'all love pics but I can't get to it till prob Monday or so but maybe if someone has had this prob they could help me test or diagnose.

So far my my thoughts are either in the power supply but more towards the main board.

I know this description is really in the dark but I will get more info for you on Monday such as the pics and voltages on each pin.

Thanks

Hello!

And good afternoon! My name is Amanda Maffei here with the Sony Support team. We do apologize to hear that about your KDL40EX700. Have you been in contact with our Technical Support? If not please do call them at your earliest convenience at: Priority Service: 239-768-7547 Hours:

■Mon-Fri 8:00am-12:00am (Midnight) ET
■Sat-Sun 9:00am-8:00pm ET

They will provide you with troubleshooting tips over the phone, and if that doesn't fix the issue they will look into further options on getting this resolved. We hope this helps! Thank you! =)

-Amanda Maffei

Sony Support USA

[killian6pk]

Re: Sony KDL-46EX700 - No Screen

Hello!

And good afternoon! My name is Amanda Maffei here with the Sony Support team. We do apologize to hear that about your KDL40EX700. Have you been in contact with our Technical Support? If not please do call them at your earliest convenience at: Priority Service: 239-768-7547 Hours:

■Mon-Fri 8:00am-12:00am (Midnight) ET
■Sat-Sun 9:00am-8:00pm ET

They will provide you with troubleshooting tips over the phone, and if that doesn't fix the issue they will look into further options on getting this resolved. We hope this helps! Thank you! =)

-Amanda Maffei
Sony Support USA

It sure is nice to see that at least one company thinks enough of their product to offer support. Thanks very much for helping this person.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

Ok so here are the voltages I found.

(Pins 1 through 15) (To the main board)
1- STBY3.3V: 3.3V
2- AC_OFF_DET: 3.3V
3- POWER_ON: 3.3V
4- AUDIO12V: 12V
5- AUDIO12V_GND: --
6/7- REG12V_GND: --
8/9- REG12V (X2): 12V
10- BL_ERR: 3.3V
11- BL_ON: 0V
12- DIMMER: 0V
13- DIMMER-DC: 2.8V
14- T-CON_Vcc12V: 0V
15- T-CON_ON: 0V

(Pins 1 through 4) (supply to the T-CON)
1/2- T-CON_Vcc12V: 0V
3/4- T-CON_12V_GND: --

And ya wow was not expecting that from Sony. Well I will definitely give y'all a try then.

[budm]

Re: Sony KDL-46EX700 - No Screen

OK, the main board is sending out the PS_ON signal of 3.3V which is enough, so you need to check the DC voltages on those two large DC filter caps to see if the PFC is working or not, when the TV is plugged in, the voltage on the caps should be around 165~170Vdc, when you hit the power switch, the main board will send out the PS_ON, that should start the PFC voltage booster that should bring the voltage on the caps to be about 400Vdc.
The BL_ON and T-CON on signals are generated by the Main board. Since this an edge lit LED, there should be some small boards for the LED's power supply some where. Can we see the whole back of the TV?
So check and see if the PFC is working first.
The BL_ERR (backlights error) of 3V, I am not sure if 3V= good, 3V = bad.
Do you have the model number of the LCD panel, the spec sheet will tell you what it should be.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

I will be around it tomorrow so I will check that cap and can get that model number.

Actually those are the only boards on the back surface of the panel. It kinda threw me that this was an LED since I was used to that driver board (as I call it) for the LED's that is on the later models (well a 46nx800 and maybe some ex series) but the wires going to the panel were really skinny nor was there any inverter on the p/s. Maybe its on the side? But on the left (top right in pic) of the power supply those are the two connectors for the LEDs I would presume.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

Well irregardless of what the front display is (red or green) the power supply is emitting those voltages posted above and the voltage on the caps is 396v. There is an initial click when you plug it in but thats it. Oh and here is the whole back.

Panel is a Sharp LK460D3LA8S

[budm]

Re: Sony KDL-46EX700 - No Screen

It looks like the two plugs with red and blue wires are for the backlights LED's.
The PS_ON and the PFC circuits are working. So it is either the Main board is bad because it is not sending the BL_ON to the power supply board.
What you need to do now is to monitor the BL_ON signal to see if it even change state at all, put the DC meter on that BL_ON pin, then plug the TV in, see if it change, if not, turn on the power switch and see if it changes state or not. If it stays lo, then do the same at the BL_ERROR pin to see if it changes state also with the same procedure.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

The BL_ON does nothing at all.
The BL_ERROR is .74 (when that power savings switch is on (so set is off)) and then whether it is "on" or "off" it is the 3.3v

[budm]

Re: Sony KDL-46EX700 - No Screen

The BL_ON should at least change when the TV is turn on because it should at least try to turn on the backlights, and after that if the backlights do not turn on then the error signal will be generated. Since the BL_ON is generated by the Main board, that is the next place you need to look at, there should be voltage regulators on that board.
I do not see them on that side of the board from you picture, but I do see that the main board has fuse/s on the board, you can see F1001, mad may be more that I cannot see, the voltage regulators may be on the other side of the board also.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

Just out of curiosity, what is the generated signal? Higher voltage or no voltage...since there is already 3.3v on it?

And ya, there is a few spots that say F1000, F1001, F3700, F3701, F3702 with that 3.15 amp marking but I do not see what it is referring to. That may be for a different design of the board.

[budm]

Re: Sony KDL-46EX700 - No Screen

The generated signal can be HIGH or LOW; I.E. most power supply will need PS_ON signal to swing HIGH (usually >3VDC, the PS_ON will be sitting at LOW (0V) when power supply is OFF) to turn it on, that means the main board will have to generate the HIGH signal (done by the processor chip and associated components) and send that signal to the power supply board. Some other power supply board may need to have the PS_ON isgnal swing from HIGH to LOW to turn it on.
"since there is already 3.3v on it" which signal is this one?

[drpj23]

Re: Sony KDL-46EX700 - No Screen

That is BL_ERR.
Oh and I did find the fuses :P....they are very minute and look like small smd resistors....the back of the board was much clearer and what it was referring to so now I see them. The only thing close to a regulator I see has the numbers 55 250 A0 9A on it unless Sony uses a 6 to 8 legged IC or bigger. But if things are pointing to a main board I might as well go for that but I can continue working on it......especially since this part is unavailable right now :P

[budm]

Re: Sony KDL-46EX700 - No Screen

What we need to do is to feed about 5V from the standby power supply through 1K resistor to the BL_ON PIN, but you MUST disconnect this line that goes back to the main board since the transistor that is used for switching the BL_ON may be stuck on, that will load down the BL_ON line which will not allow the BL_ON to go high when we apply the signal through the 1K resistor.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

My standby is 3.3 I don't have a 5 on that board, but to be clear, jump that voltage to BL_ON and just take that line out of the connector.

[budm]

Re: Sony KDL-46EX700 - No Screen

That BL_ON from the main board that is fed into the power supply board BL_ON pin will have to be disconnected some how by taking that line out off the connector.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

Ok so I jumped it and no backlight but the (-) out for the LED was around .5 volts (unsteady) the (+) out for it was always at 178v. The jumper seem to have no effect.

The (-) out is the top connector and (+) out is the bottom one

[budm]

Re: Sony KDL-46EX700 - No Screen

Those connectors are for the backlights LED's. I am surprised that it has 178V there all the time, and the voltage is really high to drive the edge lit LED assemblies. I am not sure what is next at this point without having the diagram to see how this TV works.

[drpj23]

Re: Sony KDL-46EX700 - No Screen

Ok, I actually found a repair guide for the tv so if there is no dimmer signal, the backlight will not cut on. On the outputs of the p/s for the LED the (+) out is supposed to have a constant 160vdc while the (-) out can vary from 145-85vdc. In the event of no backlight the set is "supposed" to shut down but if not that is usually isolated in the T-CON (since it controls dimmer settings). If that doesn't fix it then it says panel ....which kinda doesnt make too much sense to me......but Im still weary of the main board due to no BL_ON signal and the fact that the power supply always remains in an "ON" state, it never goes into standby (but the standby light and on light will change normally).

BTW here is the guide, it is extremely informative for other stuff too.