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Old February 9th 08, 07:02 PM posted to sci.electronics.repair
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Default Replacing EL backlit LCD with LED backlit LCD - Again

I posted about this a few weeks ago, but I still have a concern.

I deal a lot with a legacy device with an EL backlit LCD. The backlight
on this unit fades badly over time and the inverter is also prone to
failure, so I sometimes need to fix them. Not only that, but EL backlit
LCDs seem to be getting hard to find, and in particular the LCD module
used in this unit is now almost impossible to find.

So I'm thinking of using LED backlit LCDs, which are much easier to
find. The inverter for the original LCD takes 5V dc input and produces
100V ac at 400Hz. I'm thinking of just bypassing the inverter altogether
and route its 5V dc input directly to the LED backlight.

Here's my concern. The LED backlit LCD's I've seen all indicate a 1/16
duty method for the backlight. I assume that means a PWM source which
is on only 1/16 of the time. If that's the case, I think it blows my
plan, since that would require a microprocessor or something.

Is my concern founded, or should I just go ahead and hook a continuous
5V supply to the LED backlight?



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Old February 9th 08, 07:54 PM posted to sci.electronics.repair
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First recorded activity by DIYBanter: Jul 2006
Posts: 6,772
Default Replacing EL backlit LCD with LED backlit LCD - Again


"Jim T. Kirk" wrote in message
. ..
I posted about this a few weeks ago, but I still have a concern.

I deal a lot with a legacy device with an EL backlit LCD. The backlight
on this unit fades badly over time and the inverter is also prone to
failure, so I sometimes need to fix them. Not only that, but EL backlit
LCDs seem to be getting hard to find, and in particular the LCD module
used in this unit is now almost impossible to find.

So I'm thinking of using LED backlit LCDs, which are much easier to
find. The inverter for the original LCD takes 5V dc input and produces
100V ac at 400Hz. I'm thinking of just bypassing the inverter altogether
and route its 5V dc input directly to the LED backlight.

Here's my concern. The LED backlit LCD's I've seen all indicate a 1/16
duty method for the backlight. I assume that means a PWM source which
is on only 1/16 of the time. If that's the case, I think it blows my
plan, since that would require a microprocessor or something.

Is my concern founded, or should I just go ahead and hook a continuous
5V supply to the LED backlight?



I've used LCD panels with LED backlighting, and just run them from DC. Some
are specced to just run straight from 5v, and some require a series
resistor. I would just go ahead and try one of the panels that you are
intending to use, and put a resistor in series first, and see what the
brightness and current draw is like.

Arfa




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