I have a SHARP tv with an AUO panel. When I got it, the backlight wasn't working. Found lots of bad LEDs. Replaced some with what I had (3v 1w LEDs) and tested. All the strips are working now, but the drive current is about 500mA on both drive circuits. Has anyone seen an LED drive at 500mA--seems quite high and likely to burn out these LEDs. I checked the current sensing resistors and they seem ok. I suspect I need to buy some 1.5w LEDs to do a correct repair.
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Re: Sharp LC-50UB30U backlight drive current
Are the original LED 3V or 6V (dual LEDs in series)?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=24809 -
Re: Sharp LC-50UB30U backlight drive current
The original LEDs are 3v. There are 32 on each string (2 total strings). When I tried to replace all of them with the 350ma replacements, the led driver would shut down right away. I added a few of the original ones that were working back and the strings light again with current measured at 500ma.Comment
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Re: Sharp LC-50UB30U backlight drive current
Are LEDs connected as ONE string or you have more than one string and with individual LED string drive circuit?
Is this your board? It has two LED drive circuit, so each string showing 500mA?
What are c304, c404 Voltage rating?
http://www.shopjimmy.com/sharp-0500-...-led-board.htm
Sharp 0500-0605-0840 Power Supply / LED Board
LED strips: http://www.shopjimmy.com/sharp-ic-a-...lc-50ub30u.htmLast edited by budm; 02-07-2017, 11:29 AM.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 LC-50UB30U backlight drive current
Yes, those are the board and strings. There are two strings and two drive circuits. The working voltage for c304 and c404 is 250V. I am getting 500mA of current in each string. The drive voltages are 117.16vdc with return of 26.569vdc and 117.16vdc with return of 25.857vdc.
A magnified photo of one of the original LEDs is attached.Attached FilesComment
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Hi everyone,
I'm in need of assistance with a Dell Precision 5820 Tower. The BIOS is locked with "Dell Security Manager," preventing access to the HDD-1 hard drive.
**Background:**
I recently purchased this Dell Precision 5820 Tower from a recycler who salvages equipment from abandoned office spaces. The computer was left behind by its previous owner and was password locked. Given that it can run Windows 11, I saw this as an opportunity to upgrade my setup.
**What I've Tried So Far:**
1. I accessed... -
So I've worked on dozens of HP and Dell laptops and have never encountered this before.
Steps taken in my usual process.
Reset security settings in the BIOS
Ensure existing HD comes up into the OS
Shut down the laptop and disconnected the main battery
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Replace battery connector and close up the laptop
Insert my USB drive with my Windows 10 image I've... -
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