How does PDIM work? (Soyo backlight problem)


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How does PDIM work? (Soyo backlight problem)

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bloodchange
New User

Dec 11, 2012, 1:27 AM

Post #1 of 2 (3510 views)
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How does PDIM work? (Soyo backlight problem)	Can't Post

I'm a newbie and I'm also new to flat screen TV's. (I've repaired a few CRT TV's before, but I'm not a pro.)
I'm trying to fix my Soyo MT-SYTPT3227AB that has a V144-JO2N backlight inverter board. I get sound, but no picture.
I'm getting power to the inverter board, but the lights won't light. I get 24V across each of the electrolytic caps. There is a twisted pair of green and yellow wires that connect to the OFF/ON pin and the PDIM pin (12&13). Both of them are at 5V (reference ground--not 5V between 12 and 13).
How does PDIM work? Is it either high or low (5V or 0V) or is it a range of voltage? (proportionate control) If it is the former, should it be at 5V with the backlight totally dimmed?

74f100
Enthusiast

Dec 20, 2012, 6:34 AM

Post #2 of 2 (3421 views)
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Re: [bloodchange] How does PDIM work? (Soyo backlight problem) [In reply to]	Can't Post

Normally it goes high to turn on the inverter (5vdc or less).

Well, actually the pdim will vary depending on the video. The off/on is initially the important one, make sure it goes high and stays. If not, there is a problem with the main (or rare cases power supply). If both the on pulse and the pdim go high with 24vdc drive the inverter should light. If not it's a problem with the inverter or panel.

Ok, my fingers are tired typing.

Good luck,
Jim
HDMI not working

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