Author Topic: Hitachi LCD 42HBT42u Issues, Stanby Lights Flashe but Screen is Blank  (Read 461 times)

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downunder

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If you have access to the terminals on each LED, the Fluke in diode mode should illuminate each individual LED (This is not always the case). The polarity of the meter leads is important. If no light when connected one way, try reversing the leads.

If not, count the number of diodes in each strip, multiply it by 3 (3V per LED) gives you the voltage you need to apply to the input of each strip. So a strip of 12 LEDs will need 36V. Any strip that doesn't light up will have faulty LED/LEDs on it. Heat discolouration on a particular LED may give it away.

Most of us have a LED tester by now. Connect it to a strip, and it automatically adjusts the voltage up until the strip lights up.

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vinceroger69

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you can use two aa batteries like in this video some people also test the leds in each direction using the diode mode on there multimeter
https://www.youtube.com/watch?v=eEJoPCa7Kt0
https://www.youtube.com/watch?v=ZSJ4ETkLTF4
https://www.youtube.com/watch?v=K_VfM4grw3I
https://www.youtube.com/watch?v=YgaL6X6eSaU proper led tester
« Last Edit: March 10, 2017,05:46:46 by vinceroger69 »

jjuk26

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Hi Guys, i wired up an 18volt drill battery and tested, the one strip did not work, there is a strip on eBay for sale but its a used one do you know the best place to get a new one?

LB43007 VO_01_38S

KS-D 94V-0 E465853 15 16 (IN GOLD BIGGER WRITING) 7193A 81010

17DLB43VLXR1   and the letter A

Thanks

Jason

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Turnip

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Hi,

When first trying check Leds, I assumed that the Copper area either side on the strip was anode/cathode. It isn't of course, just the heat sink connected to the larger cathode area of the Led.

The anode connection is to a thin printed track leading to the next Led in line, and next to the -ve which runs along the length of the strip (With usual LG strips)

Currently use a current limited power supply but notice China does automatic Led testers showing voltage and current for less than 15.00 inc post - Chris.

jjuk26

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Hi Turnip, thanks i have located the faulty strip, just need to know best place to purchase now :)
Thanks

Jason

vinceroger69

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Hi Turnip, thanks i have located the faulty strip, just need to know best place to purchase now :)
Thanks

Jason

If your in the uk you can try ohms supplies, how many leds have failed on yours? as maybe possible to replace them all in one go

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jjuk26

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Hi Vinceroger69, the whole strip has gone

Thanks

Jason

vinceroger69

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I have never had a whole strip go before yes one or two have you tested each led with 3v battery? as if one is shorted may stop the whole strip lighting up and depending on what lcd panel your set uses maybe this strip
http://www.ohmsupplies.co.uk/epages/62027733.sf/en_GB/?ObjectPath=/Shops/62027733/Products/LED13-Z1.01
« Last Edit: March 10, 2017,14:34:57 by vinceroger69 »

Davy

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Just wondering that's all. If one or more LED's have gone, would it not be better to change the entire lot and have done, better than to do it once than keep having to do it, my way of thinking is when are the others going to 'pop their clogs'.... might be next week or never?

Dave

vinceroger69

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Just wondering that's all. If one or more LED's have gone, would it not be better to change the entire lot and have done, better than to do it once than keep having to do it, my way of thinking is when are the others going to 'pop their clogs'.... might be next week or never?

Dave

yes this is my thoughts too now, as in changing the lot in one go then turn down backlight level as should last a lot longer then as each time you have to strip the lcd panel down more chance of cracking it or tab bond damage.

t1412

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when you replace the led strips is it best to do a firmware updated if possible thanks

shaun   

 

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