Diagnosis of a 40AO2USB TV that's stuck in Standby

[arizanotlari]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Thank you Arizanotlari & Dick_Barton for your suggestions.

Dick_Barton: I can't find U500 on my PSU Board! Am I searching in the wrong place or is my Board different to what you expected?

Also (and please excuse my ignorance), could you simplify your second point about connecting the two resistors to CN4?

(I do have a stand-alone Voltage Generator, and I can adjust Voltage & Current - could I switch the TV Off, disconnect the 2-wire connector driving the LEDs and apply a voltage to the two pins to test the LEDs? If so, what Voltage should I set?).

Arizanotlari: You suggest I check the MB: Any specific checks I should make?

Again, thank you both for giving up your time to guide me!

Vestel mainboards software breaks very easily. What is main board name?

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Understood. I will try and find a 1K Resistor and do as you suggest. That will be a good test to do.

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Hi Dick_Barton

I did as you suggested: Unplugged the CN4 Connector from the MB. Then connected my external 5V Supply in series to a 1K Resistor with the other end on Pin 5 of CN4 (which if my topology is correct is the 3rd Pin up from the bottom - Pin 1 has 24V on it). The other end of my 5V Supply was attached to the TV chassis. Turned TV ON, and no LEDs came On. Do you think that is a definitive Test that the LEDs have an Open Circuit?

Thank you!

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Hi Arizanotlari

The TV is Techwood 40AO2USB.

The Main Board is Marked as Vestel 17MB100.

Other Markings on Board (Yellow Label): 23306077 52763, V31336 LN7 SCY, 18/10-12/8-330.

There is also a White Barcode:10099021 23306075 121 40" 27452763 DIJ 31336.

Thank you!

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Just realised that the test I did earlier with the 5V supply was flawed!

As I could not find anywhere convenient to attach (or solder on) the external 5V wire onto Pin 5 of CN4 I turned the TV ON and then touched the 5V on the CN4 Pin 5. I realise now that this is not a valid test as I assume the 5V on Pin 5 is an enabler signal for the TV to then turn on & retain the Voltage for the LEDs. (I assume what happened was that as soon as the TV turned ON and the 5V level was not there the TV still dropped into Standby, and hence when I then touched the 5V onto Pin 5 nothing would have happened).

I shall repeat the test tomorrow properly and I shall post the result.

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Hi again

I repeated the test with the 5V this morning but no joy.
In fact if I unplug the MB from the PSU Board I can't get the TV to do anything (does not flash the blue led and does not go into standby).
When I plug the MB back (having removed the external 5V) it does as it did before (flashes the led for some 10 times, then steadies). When I press any channel it flashes the led again some 10 times and turns off the led altogether).

Is there a more definitive test I can do to check out the leds?

Thank you

[dick_barton]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

If I have this right, with the mother board disconnected from the power supply all the voltages on the power supply are correct. If you then apply 5V to BL_ON-OFF the backlights do not come on.

If that's the case then I would strongly suspect the led driver IC or a led(s) fault.

[arizanotlari]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

https://drive.google.com/open?id=0Bw...UpENkdTSHhOMnM
Check voltages.
Try installing this firmware via usb (dont use blue usb ports) : https://yadi.sk/d/WetNg-bt2I6_Og

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Hi Dick_Barton:

As I was struggling to make progress (due to my limited competence) I bought a 2nd hand MB for £12 from eBay and swapped with existing: No Change, exactly the same fault as before, so I suspect it is not the MB. As the PSU Voltages appear OK I am inclined to agree that some (or all) of the LEDs have failed or there is some key disconnect issue inside (unlikely).

I have looked to see if I can get replacement LEDs but these are no longer sold! So, I think I am coming to the end of the line.

Just one final question: I am happy to go carefully and open up the TV, remove the screen (I know VERY VERY carefully) and then the Diffusers and White Paper Underlay to get access to the LEDs - if nothing else as a learning exercise for me. Do you have any key advice for doing this - I have looked at some YouTube videos and feel reasonably confident to give it a go! If I do get that far and discover faulty LEDs do you know what replacements I should use? I assume RS (in the UK) would source a wide variety of these?

Arizanotlari: Thank you for posting the MB Drawing, but as outlined above it does not seem to be the culprit. As far as reloading the Firmware I have no idea how to go about doing this.

Finally, Thank you to both of you for supporting me and giving me ideas on the way.

[dick_barton]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

There are a lotof threads regarding removing the lcd panel and ensuring you do not mix up the order or direction of the layers below. 40" panel should not be an issue if you are careful and do not bend the panel.
I would take time to familiarise yourself and as you say there are plenty of Youtube video's to guide you.

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Thanks - yes, I will take my time, make sure I have help lifting the screen and will make good note of order etc. Re-assuring to know that it is not beyond attempting!

[cheeky2]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

I think I have a set of LED's from this TV set that came in with a broken screen. I will have a look as I was going to list them on ebay later on together with the working boards.
Reading the information I would say one or more of your leds have failed, if you can turn on and off your TV with the remote control.
I cannot recall if this set has a scart connector. If it does then I would hook it up to a fully wired scart lead and play media through the scart connection. Ensure you turn tv on first then turn from standby to on your scart connected device (ie dvd player with cd inside) then lay the media. If you get audio and you can adjust volume from remote then you can safely say your main board is good.
It would then point to leds or issue with PSU.
Good luck

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Thanks Cheeky2, I have checked and there is no Scart interface.
Let me know if you find the LEDs.

[cheeky2]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Just looked and I have the Techwood 40AO2B model and your model doesn't have any scart connectors. Though if your familiar with using the remote control with the TV you could select the different inputs and connect a input via one of the hdmi connections (playing audio through it) and see if you can get audio.
Aaah just read your post above after posting this!
Good luck just off to list the boards for it!

[vinceroger69]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Just looked and I have the Techwood 40AO2B model and your model doesn't have any scart connectors. Though if your familiar with using the remote control with the TV you could select the different inputs and connect a input via one of the hdmi connections (playing audio through it) and see if you can get audio.
Aaah just read your post above after posting this!
Good luck just off to list the boards for it!

cheeky2 slightly of topic just saw you sell used boards on ebay i have been selling used ones from cracked sceen sets i have tested as working etc im finding people are buying mine too fault find there own say a psu they buy mine put it in there tv and find out its a mainboard issue instead then request a refund saying mines defective or faulty (which it isnt) and ebay back the buyer up have you found a way around this issue? as im usually out of pocket after paying return postage etc.

[Varoshiotis]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

I am also going off topic and not an area I know much about! However, when I recently bought a 2nd hand MB from eBay (to try in my TV, which showed my original board was OK) the condition from the Seller was that they would consider a return (and a refund) however the return postage had to be paid by me (the customer); this I thought was more than fair. In my case, and for a board that cost just over £10, it did not make sens to go into the bother of returning it and I may as well keep the board as spare (assuming I fix the damn TV!).

[vinceroger69]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

I am also going off topic and not an area I know much about! However, when I recently bought a 2nd hand MB from eBay (to try in my TV, which showed my original board was OK) the condition from the Seller was that they would consider a return (and a refund) however the return postage had to be paid by me (the customer); this I thought was more than fair. In my case, and for a board that cost just over £10, it did not make sens to go into the bother of returning it and I may as well keep the board as spare (assuming I fix the damn TV!).

That certainly sounded fair from your ebay seller but because my ebay buyer stated on the return (he worded the board faulty/defective ebay made me send a returns label at my cost) i have read a few posts regarding ebay even if you list something as spares or repairs the buyer could still return it i even phoned ebay and explained the buyer was probably just using my working board too fault find his own tv they didnt want too know i had to just refund them once the board was returned too me.

[cheeky2]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Ebay always backs the buyer in pretty much every case. I advise people of any led TV of failed leds (which is most TV's now I repair), so I sell the whole set of boards for the TV rather than selling individually.
Idiot buyers on ebay just look at the pictures and tiltle in most cases I find! Though I have been harsh in warning people on ebay that I will cancel there bid (refund them cheaper long run) and block them from buying in cases where I expect a return as a result of misdiagnosis if they don't contact me before purchase with there symptoms! That so far has worked and saved me a return and earned me a £10 from one potential buyer who I resolved his issue without a purchase (generous guy who was very pleased as he wouldn't have found the fault without my help). They are out there but it is annoying when you have a return from an item you know works.

cheeky2 slightly of topic just saw you sell used boards on ebay i have been selling used ones from cracked sceen sets i have tested as working etc im finding people are buying mine too fault find there own say a psu they buy mine put it in there tv and find out its a mainboard issue instead then request a refund saying mines defective or faulty (which it isnt) and ebay back the buyer up have you found a way around this issue? as im usually out of pocket after paying return postage etc.

[nomoresonys]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

Indeed, that's the way to do it, I always ask them their symptoms and won't sell them one if I don't think it's their problem and try to help them with diagnosis.

[electro-raf]

Re: Diagnosis of a 40AO2USB TV that's stuck in Standby

hi i know this is an old post any idea what the number on the led strips are as i cant find any with model number. its for a friend and he hasnt opened tv yet.

cheers