Soniq E40W13C-AU TV Stuck on standby

[zantesu]

Hi everyone

Attempting my first ever LCD/LED TV repair. The problem is that the TV has power but is stuck on standby. When the power button on the TV or the remote is pressed, there is no response. The LED at the front of the TV just stays red and doesn't blink or flash or do anything else.

I opened the back of it apart and saw no visible sign of the typical capacitor faults discussed in other threads; bulging, leaking etc. However, I decided to replace all the capacitors, except for 2 (The big one and the second biggest one) because I'm still waiting for it to be delivered, with panasonic, rubycon and nichicon ones (Low ESR where appropriate).

I checked the voltages at the terminal connector to the mainboard, before and after the capacitors change and the results are the same.

12 V ~ 12.4 V
12 V ~ 12.4 V
5 V ~ 5.1 V
5 V ~ 5.1 V
5 VS ~ 5.0 V
STB ~ 5.0 V
ON/OFF - 0V
ADJ - 0V

From these results I am assuming the issue is with the mainboard. I try finding another mainboard online but no luck. There's no schematic as far as I can tell, so I'm thinking of trying to fix the mainboard myself.

Can anyone please point me in the right direction on where to start my diagnostic of the mainboard? Which are the usual components that fail?

I try doing a bit of diagnostic myself and these are my findings:

1) All caps seems to be working fine under load (but I might replace them later just to be safe)

2) Tracing where the signal from the IR goes when I press the power button on the remote

Refer to the Attached picture

When I press the power button on the remote control the voltage at the IR terminal connector on the IR input pin changes (I think from ~5 V to 4.6 V from memory). I did a continuity test and found that the signal from that pin goes to the two SMD components in the picture I attached before it goings into the big Chip. However, the white looking component seems to fail the continuity test. The voltage change does happen on the left side of that component when I press the power button on the remote but there is no voltage change on the right side. I'm not sure what that component is to perform a proper test on it. Does anyone know? Thanks.

3) From visual inspection of the photo (I have attached this photo as well) I took of the mainboard, I also found that one of the Voltage Regulator the BM1117-ADJ looks discolored compare to the rest of the components on the board. Is this normal? or is it burnt?

Any help would be much appreciated. Thanks

Best Regards

Max

[budm]

Re: Soniq E40W13C-AU TV Stuck on standby

On/off - 0v: Backlights ON/OFF
ADJ - 0v : Dimming Control

So you are missing two signals. It may be hardware or firmware.
What you can do is you MUST remove those two signals wires that go the main board first then use one resistor (500~1K) between that ON/OFF wire and the 5VS, and another same value resistor between the ADJ wire and the 5VS.
If the other sections of the main board are OK, then you should be able to see the pictures and hear the sound an all other functions, if not then you have more that just two missing signals problem on the main board.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

Cheers thanks budm, I will try that and let you know the results.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

So I did what you said, and the backlight and screen turned on (and stayed on). However, nothing came up on screen.

It seems I'm still stuck on standby because the red LED at the front of the TV did not change; it just stayed lit up the whole time even though I was pressing buttons on the remote and the controls on the side of the tv.

I also measured the voltages across that discoloured voltage regulator (BM1117 - ADJ) and these are my findings.

Assuming pins are numbered left to right:
Between GND - Pin 1 = 141.4 mV
GND - Pin 2 = 0.790 V
GND - Pin 3 = 5.18 V

I also measured the other voltage regulator (BM1117 - 3.3)
Assuming pins are numbered left to right:
Between GND - Pin 1 = 0V
GND - Pin 2 = 3.295 V
GND - Pin 3 = 5.17 V

Not sure if the both info would help. What should I look at next?

Thanks

[CherryNOD]

Re: Soniq E40W13C-AU TV Stuck on standby

Hi, my name is Cherry. I am new here. Nice to see you. I am from China. And now I am working in an electronics company named NOD Electronics.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

Hi, my name is Cherry. I am new here. Nice to see you. I am from China. And now I am working in an electronics company named NOD Electronics.

Hi I think you posted this in the wrong thread. There's a welcome thread for new members.

[budm]

Re: Soniq E40W13C-AU TV Stuck on standby

"Between GND - Pin 1 = 141.4 mV
GND - Pin 2 = 0.790 V
GND - Pin 3 = 5.18 V"

So you have 5V at the input pin, and 0.79V at the ADJ pin, so if the IC is OK then you should have .141V +1.25Vref = 1.39VDC at pin 2, so you do have bad regulator since you are getting only 0.79VDC. You should take the resistance reading (no AC to the TV of course) between pin 2 and Ground to see if it shows low resistance, it can also have bad filter cap that is connected to pin 2 so you need to check that also.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

Hi budm, thank you for your assistance. I measured the resistance as you have suggested and here are the results:

Voltage Regulator 1 (shown in picture 1)

Assuming pin number from left to right.

Between GND - 1 = 0 Ohms
GND - 2 = 341 ohms
GND - 3 = 4 Ohms

I have also checked the capacitor, with a multimeter set to ohms, that is connected directly to Pin 3 and it seems to be charging and discharging fine.

Voltage Regulator 2 (shown in picture 2)

Between GND - 1 = 102 Ohms
GND - 2 = 454 ohms
GND - 3 = 1k Ohms

So because of these results are they faulty?

If so I can't seem to find any supplier in Australia for the BM1117 series, can I use the LM1117 series instead?

Their datasheet:

BM117


LM1117


They both have similar specs except the LM1117 series has a max output current of 1.5A.

[budm]

Re: Soniq E40W13C-AU TV Stuck on standby

"Between GND - 1 = 0 Ohms
GND - 2 = 341 ohms
GND - 3 = 4 Ohms"
This one does not look right, it is showing that the input pin has only 4 Ohms of resistance. Is this the one that has pin 2 output of 0.79V but pin 3 input pin has 5V input?
I would remove it and then do the resistance testing again on the pads of the board where the IC was soldered to see if the low resistance will go away.
Either one of those two will work as long as they are adjustable type.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

"Between GND - 1 = 0 Ohms
GND - 2 = 341 ohms
GND - 3 = 4 Ohms"
This one does not look right, it is showing that the input pin has only 4 Ohms of resistance. Is this the one that has pin 2 output of 0.79V but pin 3 input pin has 5V input?
I would remove it and then do the resistance testing again on the pads of the board where the IC was soldered to see if the low resistance will go away.
Either one of those two will work as long as they are adjustable type.

No thats the other one. Below is the overall findings so far

BM1117-3.3 (voltage Regulator Number 1)

Between GND - Pin 1 = 0V
GND - Pin 2 = 3.295 V
GND - Pin 3 = 5.17 V

Between GND - 1 = 0 Ohms
GND - 2 = 341 ohms
GND - 3 = 4 Ohms

BM1117-ADJ (voltage Regulator Number 2)

Assuming pins are numbered left to right:
Between GND - Pin 1 = 141.4 mV
GND - Pin 2 = 0.790 V
GND - Pin 3 = 5.18 V

Between GND - 1 = 102 Ohms
GND - 2 = 454 ohms
GND - 3 = 1k Ohms

[budm]

Re: Soniq E40W13C-AU TV Stuck on standby

BM1117-3.3 (voltage Regulator Number 1)

Between GND - Pin 1 = 0V
GND - Pin 2 = 3.295 V
GND - Pin 3 = 5.17 V

Between GND - 1 = 0 Ohms
GND - 2 = 341 ohms
GND - 3 = 4 Ohms

BM1117-ADJ (voltage Regulator Number 2)

Assuming pins are numbered left to right:
Between GND - Pin 1 = 141.4 mV
GND - Pin 2 = 0.790 V
GND - Pin 3 = 5.18 V

Between GND - 1 = 102 Ohms
GND - 2 = 454 ohms
GND - 3 = 1k Ohms
OK, one thing for sure is that the one with 0.79V output on pin 3 is not right so I would replace it.
But the other one that shows 5.17VDC on pin 3 but it has 4 ohms to GND, that has to be error in resistance reading since @5.17V with 4 Ohms you are talking about 1.3A of current with >6 Watts of power dissipation! That has to be an error.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

BM1117-3.3 (voltage Regulator Number 1)

Between GND - Pin 1 = 0V
GND - Pin 2 = 3.295 V
GND - Pin 3 = 5.17 V

Between GND - 1 = 0 Ohms
GND - 2 = 341 ohms
GND - 3 = 4 Ohms

BM1117-ADJ (voltage Regulator Number 2)

Assuming pins are numbered left to right:
Between GND - Pin 1 = 141.4 mV
GND - Pin 2 = 0.790 V
GND - Pin 3 = 5.18 V

Between GND - 1 = 102 Ohms
GND - 2 = 454 ohms
GND - 3 = 1k Ohms
OK, one thing for sure is that the one with 0.79V output on pin 3 is not right so I would replace it.
But the other one that shows 5.17VDC on pin 3 but it has 4 ohms to GND, that has to be error in resistance reading since @5.17V with 4 Ohms you are talking about 1.3A of current with >6 Watts of power dissipation! That has to be an error.

I think you're right I double checked it again with 2 multimeters and the results are:

BM1117-3.3 (voltage Regulator Number 1)

Between GND - 1 = 0 Ohms
GND - 2 = 341 ohms
GND - 3 = Increase / decrese in ohms (possibly due to the capacitor it is attached to?)

[budm]

Re: Soniq E40W13C-AU TV Stuck on standby

Good, go ahead and replace that ADJ LDO IC with the 0.79VDC output then. I would get more than one in case it gets damaged.

'GND - 3 = Increase / decrese in ohms (possibly due to the capacitor it is attached to?)' Can be due to some left over Voltage that the caps did not completely discharged.
It is good to always check when the readings do not make sense, you can use Ohms law to see that what you are seeing is impossible.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

Cheers thanks budm. I've ordered the part and will update you on the result.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

Hi Budm, thanks for your advice I replaced the ADJ LDO IC and the TV finally turns on. It behaves while no input is in but when I plugged in the chromecast, it behaves for about 5 second and then the image is distorted. Please refer to the pictures. Thanks

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

Sorry does anyone have any idea what I should test or have a solution for this problem? Thanks you.

[stj]

Re: Soniq E40W13C-AU TV Stuck on standby

when it does that, do the osd menu's still work?

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

No the menu does not seem to work at all. The problem has evolved, if you can say that, so instead of bad picture, the TV just keeps on restarting. So it will turn on, picture is good, then restart.

[zantesu]

Re: Soniq E40W13C-AU TV Stuck on standby

I think I'll closed this thread as the original problem was solved. The TV is no longer stuck on standby and the fix was to replace a faulty ADJ LDO on the main board. Thanks budm for your assistance.

[stj]

Re: Soniq E40W13C-AU TV Stuck on standby

maybe check the other regulators incase one is overheating

infact maybe your replacement is bad because something is overloading it?