Folks,
I am troubleshooting the backlight problem in this presentation monitor. The backlight is comprised of 14 pairs of LED strips; each strip has 15 LEDs => there are 30 LEDs in series per each driver channel.
The LED PSU has 14 channels. Each channel provides 180v DC so it appears that each LED sees 6v DC applied to its terminals.
According to page 12 of the attached LCD datasheet each individual LED sees 57ma of current passing through it.
I connected a 70v DC power supply to a series of 5 LEDs (instead of connecting a 90v DC power supply to the whole strip of 15 LEDs as I did later) for testing purposes and one LED went "zap!" before my eyes. Call me an idiot if you must. Should've bought that awesome automatic LED tester from China...
Now I am trying to replace this one LED that I burnt out of negligence. Attached are some pictures of one burnt LED and one good LED. Please note that this LED has two chips connected in series. It measures 2.8mm x 2.8mm and has a lens on top of it. It looks like one of those super bright Cree devices.
I have a bunch of LED strips scavenged from several Vizio TVs with busted screens. However they appear to be different (only one chip is visible) and I am reluctant to put one of those into the Sharp. I have attached a picture of a Vizio LED also.
Before I dive into the Digi-Key catalogue, could you folks please confirm my assumptions that I need an LED with 6v DC forward voltage, ~60ma current and presumably cool white illumination hue? Does anyone know what kind of LEDs Sharp uses?
I am troubleshooting the backlight problem in this presentation monitor. The backlight is comprised of 14 pairs of LED strips; each strip has 15 LEDs => there are 30 LEDs in series per each driver channel.
The LED PSU has 14 channels. Each channel provides 180v DC so it appears that each LED sees 6v DC applied to its terminals.
According to page 12 of the attached LCD datasheet each individual LED sees 57ma of current passing through it.
I connected a 70v DC power supply to a series of 5 LEDs (instead of connecting a 90v DC power supply to the whole strip of 15 LEDs as I did later) for testing purposes and one LED went "zap!" before my eyes. Call me an idiot if you must. Should've bought that awesome automatic LED tester from China...
Now I am trying to replace this one LED that I burnt out of negligence. Attached are some pictures of one burnt LED and one good LED. Please note that this LED has two chips connected in series. It measures 2.8mm x 2.8mm and has a lens on top of it. It looks like one of those super bright Cree devices.
I have a bunch of LED strips scavenged from several Vizio TVs with busted screens. However they appear to be different (only one chip is visible) and I am reluctant to put one of those into the Sharp. I have attached a picture of a Vizio LED also.
Before I dive into the Digi-Key catalogue, could you folks please confirm my assumptions that I need an LED with 6v DC forward voltage, ~60ma current and presumably cool white illumination hue? Does anyone know what kind of LEDs Sharp uses?
Attached Files
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