Re: 17ips20 diagnosing
Thanks, I'll give them a try when i can spare a few quid.
formant84
Member
Last Activity: 11-22-2016, 03:14 PM
Joined: 11-05-2016
Location: merseyside
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Re: 17ips20 diagnosing
It's an ISIS 39227FHDDLED. Similar chassis to other cheap TVs with this vestel board.
The new LEDs are dimmer.
Is there any safe way to bypass the relevant LEDs to see if the backlight comes on?Last edited by formant84; 11-22-2016, 02:32 PM.Leave a comment:
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Re: 17ips20 diagnosing
Hi Alan,
Well the ones I've replaced are a slightly different brightness, they aren't the exact right ones but I would have thought that as long as they light up and don't blow they would be okay. I guess this is not the case?
Do you think this is most likely to be the problem, or is it still possible that a fault on the power board is resulting in a shortage of current to the LEDs despite the correct voltage being supplied?
Thanks,
John
PS: Dick, sorry for being short with you, this TV is...Leave a comment:
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Re: 17ips20 diagnosing
Yeah like I said the first two times, I have tested all of the LEDs individually and they're all working.Leave a comment:
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Re: 17ips20 diagnosing
Yeah tested every one, and like I said they all flash on for a split second as the voltage jumps to 190v, so they're all working.Leave a comment:
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Re: 17ips20 diagnosing
I Assume the LEDs are powered from a constant current source which isn't working, giving them a spike and then virtually nothing. I've tried measuring the current with my multimeter and it's either around 1ma or the fuse in my multimeter has blown :/Leave a comment:
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Re: 17ips20 diagnosing
Turns out the new LEDs are fine. They all flash once just as the voltage goes up to 190 but then go off straight away before it settles down to 115v. Any ideas?Leave a comment:
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Re: 17ips20 diagnosing
Replaced the dead LEDs, powered on... Still no backlight.
My guess is that my replacements couldn't take as much current as the originals and just instantly died. Got no more time to look at it today, might order the LEDs you linked in and have another stab at it during the week.
Thanks again.Leave a comment:
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Re: 17ips20 diagnosing
Yeah I'm an idiot. I was testing them wrong. Turns out there are 4 duds.
Not only that but I have some SMD LEDs that should be close enough to use. Gonna replace them now, I'll post the results.
Thanks for the advice!Leave a comment:
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Re: 17ips20 diagnosing
Yeah I realised that i had no picture or sound because it hadn't auto-selected the input like i thought it would *facepalm*
It's definitely the LEDs, but it seems like a LOT are gone. There are five strips of 9, so far i've tested three strips and found 8 working LEDs out of 27 :/
Is there anywhere to buy the SMD LEDs cheaply without having to buy the full strips?Leave a comment:
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Re: 17ips20 diagnosing
Further update:
Okay there was a problem with my hdmi adapter. The computer now detects that the to is connected but I get no picture or sound. Voltage to LEDs is okay, backlight seems to come on but rather dimly. Tried shining a torch at the screen, no sign of any kind of image.
Could this be the power board? Or am I looking at a logic board issue?Leave a comment:
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Re: 17ips20 diagnosing
UPDATE: The thought occurs that it's not powering down the logic board, but maybe exiting standby mode causes a fault either in the power going to the logic board or on the logic board itself? The logic board is a vestel 17MB55.Leave a comment:
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Re: 17ips20 diagnosing
Hi Sorry to hijack this thread but I have an ISIS branded 39" tv with this power board and I have the weirdest problem. When I press the power button, the power/standby light comes on and power goes to the logic board because my laptop detects the display over HDMI.
But when I press the power button again, the laptop can not longer detect the TV but suddenly it powers up the LEDs, going up to about 190v then down to a steady 115.5v
So basically it seems to power each part of the TV alternately, but not at the same time! ...Leave a comment:
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