hello, i have a sharp lc-50lb371u set thats has bad leds backlights. the first time i took the set apart i replaced 2 leds that were bad. the set worked good until i put it back togerther and then it only worked for about 10 minutes. i replaced the leds with some from another strip i had. took the set back apart and found 3 leds out this time. replaced with same ones i had. set worked for about 15 hours being on and then the bottom led strips were a little dimmer then the top ones. this set has 6 strips of leds, the top 4 are on led1 off the psu, the bottom 2 are off led2 off the psu. after turning the set off then back on no backlights again. i know these sets have a led problem, but what i need to know is the psu when you plug it in has no voltage on led1 or led2, when you power on the set the voltage goes to 64.8 to 95.6 then back to 64.8. i think that should be correct for this set. the problem is when you turn the set off the 64.8 voltage does not turn off. the psu still has a little hum of it working. seems like it should turn off completly. the only way to kill the 64.8 led volts once the set is turned on is to unplug it or unplug the logic board. someone plesae help, having a hard time finding led strips for this set and dont reaaly know if psu may be causeing this or logic board not shutting down psu like it should
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Re: sharp 50-lb371u leds problems
Were the replacements from another strip which matched the existing led strip for the set or just a set of similar leds?Willing to help but I'm no expert. -
Re: sharp 50-lb371u leds problems
just a set of similar ledsComment
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Re: sharp 50-lb371u leds problems
PicsAttached FilesComment
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Re: sharp 50-lb371u leds problems
I suspect that's your problem. Many leds look similar but can have different maximum current ratings. There are also 3V and 6V versions. You need to replace them with leds from an identical strip intended for that panel. It's highly probable that the ones you replaced them with were lower current rating and have stressed the existing ones causing further damage.Willing to help but I'm no expert.Comment
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Re: sharp 50-lb371u leds problems
but what about the psu not killing the 64.8 volts going to the leds when the set is powered off. should it go to 0 then when turned offComment
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Re: sharp 50-lb371u leds problems
im not thinking its just the leds here. the set is only 2 years oldComment
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Re: sharp 50-lb371u leds problems
If you were to read the many threads regarding led faults you will see that what you are describing fits the problem you have.
What is the LCD panel name and number as given on the metal back?
How many leds per strip and how many strips are there?Last edited by dick_barton; 03-31-2017, 03:46 PM.Willing to help but I'm no expert.Comment
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Re: sharp 50-lb371u leds problems
What is the spec of the replacement LED?
Vf and If rating are very important.Last edited by budm; 03-31-2017, 03:46 PM.Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: sharp 50-lb371u leds problems
But what about the psu not shutting down the 64.8 volts when you power the set offComment
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Re: sharp 50-lb371u leds problems
The leds I replaced worked for awhileComment
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Re: sharp 50-lb371u leds problems
What you need to find out if the PS-ON (ON = >2 VDC (OFF = <1 Vdc) goes low when the TV is off or not.
Same for the BL-ON (same as O/F).Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Re: sharp 50-lb371u leds problems
The panel number is tpt500j1-hvn07.u. there are 6 strips 11 leds per strip. 4 strips are off led 1, 2 strips are off led 2. Both have 64.8 volts all the timeComment
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Re: sharp 50-lb371u leds problems
Thanks buMD I'll try that in the morning and see what I can figure outComment
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Re: sharp 50-lb371u leds problems
I'm surprised that they are not balanced and that Led1 & Led2 support 3 strips each.Willing to help but I'm no expert.Comment
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Re: sharp 50-lb371u leds problems
Can you post a sharp photo of the bottom of the power supply to identify the led driver ICWilling to help but I'm no expert.Comment
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Re: sharp 50-lb371u leds problems
Here are pics of psuAttached FilesComment
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Re: sharp 50-lb371u leds problems
db needs to see picks of the under side of the ps to see the backlight circuitry.
clear straight on pics, thanks.WHY CAN'T PHILIPS USE PHILLIPS HEAD SCREWS?Comment
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Re: sharp 50-lb371u leds problems
the psu connector going to the logic board has 16 pins, 6 of them are 12v which is alway there on/ 2 are listed as 12v_a dont know what the underline means for these 2 pins. the ps_on , dim , and o/f are o volts when you plug the set in. when you power the set up ps_on goes to 3.34, the dim goes to 3.09 and the o/f goes to 3.32. when you power the set off the ps_on stays at 3.34v and the dim stays at 3.09 volts. the o/f does go to 0volts. meanwhile the led1 and led2 also stay at 64.8 volts any ideas of what could be going on. i have read these set are bad on leds but maybe its not the leds fault , maybe logic is keeping psu on all the time killing themLast edited by robert phelps; 04-01-2017, 04:35 PM.Comment
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Re: sharp 50-lb371u leds problems
http://www.shopjimmy.com/sharp-pltve...c-50lb370u.htm
Sharp PLTVEY701XAL5 Power Supply / LED Board for LC-50LB370U
Your board is XAL4, but this one looks to be the same as yours.
Pictures provided by shopjimmy.Attached FilesNever stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956
Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999
Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl
Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/
TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809Comment
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Hi There!
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Ok.. this is the story:
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This is kinda how it looked, just that mine were at the bottom of the screen:
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Hello Sharp TV experts
Our Sharp LC-80LE642U displays one short one long flash error code which is a backlight error. I went into service mode and there were 8 lamp error counts recorded. I reset the count to 0 and did a reset. The last monitor error cause was 16 B00014639:12. 16 is the code for backlight error. I tried to power the tv up but went back into error mode.
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