Sony kdl-46hx853 no power

[budm]

Re: Sony kdl-46hx853 no power

So far you have not reported the Voltage readings at the power supply connector as requested.
You said the Voltage readings are OK, so what are they showing? What are the control Voltages showing?
Also show us good clear straight shot pictures of the power supply and the main board so we can easily see the pin labels of the connectors.

"the backlights I really don’t think so bcuz all the voltages was even on every set of wires I tried" That is wrong thinking because you may be seeing the feeding Voltage to the boost converter after backlghts circuit shutdown, not the boosted Voltage for driving the LED strings, there is a proper step to test that when TV is first turned on with meter in place and after the shutdown occur, but that test will be valid only if the BL-ON (and DIM control Voltage) is present and stays present.

[imran333]

Re: Sony kdl-46hx853 no power

So far you have not reported the Voltage readings at the power supply connector as requested.
You said the Voltage readings are OK, so what are they showing? What are the control Voltages showing?
Also show us good clear straight shot pictures of the power supply and the main board so we can easily see the pin labels of the connectors.

"the backlights I really don’t think so bcuz all the voltages was even on every set of wires I tried" That is wrong thinking because you may be seeing the feeding Voltage to the boost converter after backlghts circuit shutdown, not the boosted Voltage for driving the LED strings, there is a proper step to test that when TV is first turned on with meter in place and after the shutdown occur, but that test will be valid only if the BL-ON (and DIM control Voltage) is present and stays present.

I will do that but I did show a picture of the power supply connector which has the voltage markings on it, but I did match the voltage readings to the markings on the power supply and matched them to the service manual and everything matched and I tried another power supply so, Thats why I never wrote down the power supply voltages bcuz everything seems good , but I can do that but I thought the next step was trouble shoot main board as I ruled out the power supply and the service manual tells me the same, it says if you got standby voltage on pin 10 on main board connector, then it’s your main board that’s faulty

[imran333]

Re: Sony kdl-46hx853 no power

I removed the backlights to check them and they are all functioning and I borrowed a working tcon and backlight driver but still same issue , the only board I haven’t been able to borrow is the main board as my friend who sells parts has already sold it and next I’ll post results of power supply voltages, but I have already tried replacing that board but still same problem

[imran333]

Re: Sony kdl-46hx853 no power

So far you have not reported the Voltage readings at the power supply connector as requested.
You said the Voltage readings are OK, so what are they showing? What are the control Voltages showing?
Also show us good clear straight shot pictures of the power supply and the main board so we can easily see the pin labels of the connectors.

"the backlights I really don't think so bcuz all the voltages was even on every set of wires I tried" That is wrong thinking because you may be seeing the feeding Voltage to the boost converter after backlghts circuit shutdown, not the boosted Voltage for driving the LED strings, there is a proper step to test that when TV is first turned on with meter in place and after the shutdown occur, but that test will be valid only if the BL-ON (and DIM control Voltage) is present and stays present.

About the backlight test I wasn't checking the voltages with the backlights in circuit , I removed the wires going to the backlight driver and checked with a backlight tester to see if I got any difference with the voltages on each set of wires and the voltages was all the same on each set of wires, normally if leds are bad, I'll either get short circuit or the voltages will read very high on the strip that has a faulty led, but I removed the backlights to check to rule them out and all functioning

[imran333]

Re: Sony kdl-46hx853 no power

Quick update my friend has a the same main board from the 55 inch tv sane model but 55 inch, tv works fine with it to my surprise , but he wants too much money for it £50 which I don’t have right now which is a discount as he’s selling it for way more online, so just thinking how to trouble shoot the main board as I got similar board which has same components on which I can Salvage parts from, but I’m stuck on what to check on the main board , as I checked for any shorts on smd caps and nothing getting hot, but some advice will be great on what to check on the main board as I know for sure that’s the faulty board

[budm]

Re: Sony kdl-46hx853 no power

That is why we need to know what Control Voltages you are getting, right now with the bad main board we do not if it is sending out the control Voltages. So far you did not provide that, if we see what you have then we could tell if the problem is on the main board or the power supply board, etc. Right now it looks like the bad main board is not sending out all the control signals.
It is possible that the main board may have corrupt EEPROM.

[ngth82]

Re: Sony kdl-46hx853 no power

+10 to budm.

This thread hurts. Please start with Post #2... nomoresonys asked you to run Test number 3 in his signature line.

"3) Test connector from mainboard to powerboard on powerboard side with all boards hooked up, test with tv plugged in but off then hit power, report both conditions here, give pin number, pin description/name and condition both off and when you hit power on. So we can see all the voltages and what they are doing."

Something like this and use the "code" block to format this nicely. The text below is an example only. Look at the power board connector, there should be a key in white or black silkscreen describing what each pin is for.

Pin #	Name	(V)OFF	(V)ON
1	P_DIM	0.4	1.992
2	BL_ON	0	3.314
3	GND	0.06	0.06
4	P_ON	2.578	2.575
5	NC	0.02	0.02
6	A_DIM	0	3.41
7	GND	0.07	0.07
8	GND	0.07	0.07
9	12V	12.17	12.16
10	12V	12.17	12.16
11	12V	12.17	12.16
12	12V	12.17	12.16
13	12V	12.17	12.16
14	N/C	0	0

[imran333]

Re: Sony kdl-46hx853 no power

That is why we need to know what Control Voltages you are getting, right now with the bad main board we do not if it is sending out the control Voltages. So far you did not provide that, if we see what you have then we could tell if the problem is on the main board or the power supply board, etc. Right now it looks like the bad main board is not sending out all the control signals.
It is possible that the main board may have corrupt EEPROM.

Yh I will do that post the voltages but I have access to the boards at the moment as the tv is at my work place , Maybe I could try jump starting the power supply , but I’m no expert, I just want to know this for knowledge but now I know which board is faulty why are we still concentrating on the power supply and if the service manual says it’s definitely the main board , then why are we still concentrating on the main board ?

You said by the control voltages we will know which board is faulty , but I did say I tried another power supply but same problem and I tried same mainboard from 55 inch and tv works perfectly , so doesn’t that indicate it’s the main board that’s faulty ?

About the eeprom , this tv uses a emmc so it is possible it’s faulty but how do we know for sure what is the problem with the main board ?

I don’t think there’s any way to write firmware unless I had a dump and removed emmc to write it directly to the emmc

[ngth82]

Re: Sony kdl-46hx853 no power

Okay, so the TV is not necessarily accessible at all times. Got it.

On most of the newer TVs, you can disconnect the power cable between the power supply and the main board. The supply should turn on automatically. From there, you can quickly determine if the backlights turn on and you can measure the voltages at the connector that supplies power to the main board.

If the supply doesn't turn on by itself, unplug the TV from the outlet. Look at the silkscreen on the power board. According to your picture in post #16, take a 10Kohm resistor and connect pin 28 (POWER_ON) to pin 23 (STBY3.3V). When you have that done, plug it in. If it turns on, then measure the voltages on the connector to the main board.

If it doesn't do anything at all, and there are no voltages present, then we continue looking at the power board.

[imran333]

Re: Sony kdl-46hx853 no power

Okay, so the TV is not necessarily accessible at all times. Got it.

On most of the newer TVs, you can disconnect the power cable between the power supply and the main board. The supply should turn on automatically. From there, you can quickly determine if the backlights turn on and you can measure the voltages at the connector that supplies power to the main board.

If the supply doesn't turn on by itself, unplug the TV from the outlet. Look at the silkscreen on the power board. According to your picture in post #16, take a 10Kohm resistor and connect pin 28 (POWER_ON) to pin 23 (STBY3.3V). When you have that done, plug it in. If it turns on, then measure the voltages on the connector to the main board.

If it doesn't do anything at all, and there are no voltages present, then we continue looking at the power board.

Yh that's the problem I don't have the tv at home just the boards And that's one of the reasons I never posted the voltages, and uk is on lockdown so I can't just keep going there all the time , maybe I can bring it hone after bank holiday on Monday , but I'll look for 10k resistor, I don't know if I got one , but does it have to be 10k , I got 1k for sure but I haven't checked if I got anything close to 10k

[nomoresonys]

Re: Sony kdl-46hx853 no power

Ok that's a good question, what does determines the size resister that is needed??

[imran333]

Re: Sony kdl-46hx853 no power

Thanks for everyone’s help , I’m not being awkward or ignoring advice, it’s just 1 reason is I don’t always have access to the tv and the other reason, I did measure the voltages but I never wrote it down , which is my fault bcuz I just matched the voltages to the service manual and what’s written on the board and I thought that would be good enough, bcuz I did try another power supply and it made no difference and I tried another main board from 55 inch tv yesterday and tv worked perfectly , so I presumed it’s pointless keep wasting time on the power supply when I kind of know the power supply is not faulty

[nomoresonys]

Re: Sony kdl-46hx853 no power

Yes, you did confirm that, you need a schemo of the mainboard, suppose you could borrow the good mainboard again and write down whatever you can test on the good mainboard and compare it to yours and feel the chips, see if any are hotter or colder on yours in comparison.

[nomoresonys]

Re: Sony kdl-46hx853 no power

Might not work but could try a firmware update, if you do follow install instructions exactly: https://www.sony.co.uk/electronics/s...loads/Z0000283

[imran333]

Re: Sony kdl-46hx853 no power

Yes, you did confirm that, you need a schemo of the mainboard, suppose you could borrow the good mainboard again and write down whatever you can test on the good mainboard and compare it to yours and feel the chips, see if any are hotter or colder on yours in comparison.

Yh I can borrow the main board again and I can try comparing some readings , what kind of things shall I take readings from?
Maybe things like dc converter chips but what else shall I compare ?
Because we got no standby light on the faulty board, what area of the board shall I concentrate on or try and troubleshoot ?

I did check if anything's getting got but I never felt anything getting hot, maybe a small cap might be getting hot but I missed it when I felt

[nomoresonys]

Re: Sony kdl-46hx853 no power

Ok, also make note of the temps of things on the good board, say a chip or component is warm and with your board the same chip or component may be ice cold, that would mean there's a problem there, probably meaning it's bad or not getting voltage or sum such.

[nomoresonys]

Re: Sony kdl-46hx853 no power

Try that firmware update on your original board, kind of doubtful but see what happens.

[imran333]

Re: Sony kdl-46hx853 no power

Try that firmware update on your original board, kind of doubtful but see what happens.

I'll try all that hopefully tomorrow

[budm]

Re: Sony kdl-46hx853 no power

OP post #28
"You said by the control voltages we will know which board is faulty , but I did say I tried another power supply but same problem and I tried same mainboard from 55 inch and tv works perfectly , so doesn’t that indicate it’s the main board that’s faulty ?"
The main board sends the control signals to the power supply board ,no control signal then the rest of the power supply will not turn on, and if no BL-ON and Dim then there will be no backlights either, that is why we ask for control signal Voltages, if you would have reported the control Voltage in the begining then it would have saved time troubleshooting.
Right now we still do not know what control Voltages are missing, you may have multiple missing control Voltages but we do not know at this point.
The main board should have some Voltage regulator IC's, SMPS IC.s, and may be fuses too.

[imran333]

Re: Sony kdl-46hx853 no power

OP post #28
"You said by the control voltages we will know which board is faulty , but I did say I tried another power supply but same problem and I tried same mainboard from 55 inch and tv works perfectly , so doesn't that indicate it's the main board that's faulty ?"
The main board sends the control signals to the power supply board ,no control signal then the rest of the power supply will not turn on, and if no BL-ON and Dim then there will be no backlights either, that is why we ask for control signal Voltages, if you would have reported the control Voltage in the begining then it would have saved time troubleshooting.
Right now we still do not know what control Voltages are missing, you may have multiple missing control Voltages but we do not know at this point.
The main board should have some Voltage regulator IC's, SMPS IC.s, and may be fuses too.

Sorry I'm no expert, and I never always had access to the tv, I still don't have access at the moment , still waiting for my work to open, I might be able to go there weekend and I can report the voltages, this main board doesn't have any big regulators, maybe there's some really small smd regulators and there's a couple of dc concert it's near the connector for the wire that goes , to the power supply , I did check the 3 smd fuses and they seemed ok , I'll see if I can fetch the tv this weekend