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Author Topic: Planar PT1545 Monitors
Mark Gulbrandsen
Resident Trollmaster

Posts: 15887
From: Bountiful, Utah
Registered: Jun 99


 - posted 07-26-2017 02:33 PM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
Just an update on the direction I went with these. Repairing the CCFL circuit can be done, but is basically a waste of time as the semiconductors are only available out of China and a bit pricy. So I have been converting them to LED back light. Taking the LCD panel apart on these is fairly easy to do and I have done about a dozen of these now, and have my repair time down to about an hour not counting time for the silicone to cure that I use to glue the LED strips into the metal reflectors. Locating the back light switching voltage was also a bit tricky. The LED lighting needs to shut off with loss of video just like the CCFL does. If anything the LED back light is a tad bit brighter and has better contrast then the CCFL does.

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Dave Macaulay
Phenomenal Film Handler

Posts: 1939
From: Toronto, Canada
Registered: Apr 2001


 - posted 07-26-2017 09:29 PM      Profile for Dave Macaulay   Email Dave Macaulay   Send New Private Message       Edit/Delete Post 
Although elegant, why "must" the LEDs shut off on video loss?

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Buck Wilson
Jedi Master Film Handler

Posts: 828
From: St. Joseph MO, USA
Registered: Sep 2010


 - posted 07-26-2017 09:38 PM      Profile for Buck Wilson   Email Buck Wilson   Send New Private Message       Edit/Delete Post 
Excellent! Start a return/service program!

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John Roddy
Expert Film Handler

Posts: 114
From: Spring, TX, United States
Registered: Dec 2012


 - posted 07-26-2017 10:41 PM      Profile for John Roddy   Author's Homepage   Email John Roddy   Send New Private Message       Edit/Delete Post 
What's the power draw of the display with LEDs compared to CCFL? I'm wondering if it's possible to just junk the power board and replace it with a 12V/5V external brick. That would open up some interesting possibilities for power delivery…

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Marcel Birgelen
Film God

Posts: 2233
From: Maastricht, Limburg, Netherlands
Registered: Feb 2012


 - posted 07-27-2017 08:20 AM      Profile for Marcel Birgelen   Email Marcel Birgelen   Send New Private Message       Edit/Delete Post 
quote: Dave Macaulay
Although elegant, why "must" the LEDs shut off on video loss?
To save power and hours on the LEDs I presume.

It's pretty normal for a monitor to go into standby mode after the input signal is lost.

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Mark Gulbrandsen
Resident Trollmaster

Posts: 15887
From: Bountiful, Utah
Registered: Jun 99


 - posted 07-27-2017 11:01 AM      Profile for Mark Gulbrandsen   Email Mark Gulbrandsen   Send New Private Message       Edit/Delete Post 
quote: Dave Macaulay
Although elegant, why "must" the LEDs shut off on video loss?

Because if one loses the video feed as in shutting down the server, the LED's stay on but the actual screen power still shuts off, and then the screen goes bright white. It would do the same thing if the CCFL lamps did not shut off.

quote: John Roddy
What's the power draw of the display with LEDs compared to CCFL?
LED = .9 amp. CCFL = 1.15 amps. So the LED's draw just a tad bit less power. I could also include a potentiometer to be able to adjust the LED brightness. But it is just about right the way it is.

Mark

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