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...
Varoshiotis
Member
Last Activity: 10-08-2021, 04:10 AM
Joined: 10-17-2020
Location: Merthyr Tydfil
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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.Leave a comment:
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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!Leave a comment:
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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...Leave a comment:
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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...Leave a comment:
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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...Leave a comment:
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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!Leave a comment:
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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!Leave a comment:
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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.Leave a comment:
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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...Leave a comment:
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Re: Diagnosis of a 40AO2USB TV that's stuck in Standby
Dropped to 0.1V over some 10-15 mins (and slowly continues to drop).Leave a comment:
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Re: Diagnosis of a 40AO2USB TV that's stuck in Standby
On Power Up I measured 104.5 V on the Pin with the White Wire out of the PSU Board going to the LEDs. As you say this then starts dropping.
I did try shining a bright torch on the TV - Nothing seen!Leave a comment:
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Re: Diagnosis of a 40AO2USB TV that's stuck in Standby
Thanks Dick_Barton
I tried to reply twice and somehow managed to lose the response - I wonder if there is a time limit on response!)
Anyway, Yes, I think you are right - it is the 17IPS20 Revision 9 PSU Board.
Thank you for the Manual, I will study it. I am surprised that still you cannot see the photos with enough resolution - I have no difficulty doing so when I log onto the Website and read the Post. If allowed I can send the photos to you via an email?
I have located the...Leave a comment:
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Re: Diagnosis of a 40AO2USB TV that's stuck in Standby
Thank you Dick-Barton
Yes, I have realised there are several deviations of the PSU Board. I have taken a few more photos, hope they have better resolution. There is a label on the last Photo (Bottom Right) reading: 071114 R9; does that mean anything to you?
Thanks again!...Leave a comment:
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Re: Diagnosis of a 40AO2USB TV that's stuck in Standby
Thank you Dick_Barton.
I have taken some measurements from the black connector on the PSU feeding the MB. Unfortunately I do not have a drawing and so I don't know how the pins are numbered. And, I can only take the measurements from the six (6) outside pins of the connector as if I try to measure the voltage on the row of pins behind this I run the risk of shorting things out. I don't know if I pull the board out and see on the underside whether access is going to be easier! Anyhow, the Voltages on the 6 pins...Leave a comment:
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Re: Diagnosis of a 40AO2USB TV that's stuck in Standby
Hi, thanks for responding.
1. The markings on the PSU Board are: Vestel 17IPS20, 23250360 - 27447736 1006.
2. No, I have not taken any measurements as yet, but will do so once I have a table confirmed such as the one you suggested.
Thank you again!
[url]https://www.badcaps.net/forum/attachment.php?attachmentid=222042&stc=1&d=1603037237[/url]Re: Diagnosis of a 40AO2USB TV that'...<br /> 1. The...Leave a comment:
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Diagnosis of a 40AO2USB TV that's stuck in Standby
Hi, this is my first post!
I have a Techwood 40AO2USB TV which when turned on flashes a blue led and then steadies this. I assume this is a Standby Mode. I can not make the TV do anything else (other than switch off - blue light flashes again and then goes off). I assume the TV goes through it's checks, then finds something that is not right and goes into Standby. Can someone please suggest what I should check/test to narrow down whether it is the PSU Board (markings: Vestel 17IPS20, 23250360) or the Main Board (markings 10099021) or the Backlight Assembly, OR something else. I have a Fluke... -
Re: New Members - please post your introductions here
I am also new to this Forum. I looked at several before joining this one and it was clear that the members here have the in-depth knowledge to trouble-shoot a variety of devices to the nth degree and resolve faults. I did electronics at University but did not practice it afterwards, instead moving into engineering software & design, subsequently into Project Management. I retired a few years back but often diagnose and resolve faults at home and for immediate family and I am always keen to expand my knowledge and be self-reliant....Last edited by Varoshiotis; 10-17-2020, 02:29 PM.Leave a comment:
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