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I am going to be using an LCD screen for a project and the power supply gives only 2 voltages, 12V and 5V. There is 2 adjustment pins on the power supply board as well though, and I was wondering if anybody knows what they do.. It seems obvious enough, but the supply regulates the voltages so why would there be adjustment pins?.. The screen will become battery powered, so before advancing I probably should know what they do.. Anybody got any ideas?
Here's a few pics of the power supply board, and the controller board.
You can see the 2 separate adjust pins in this one
Registered Member #3215
Joined: Sun Sept 19 2010, 08:42PM
Location:
Posts: 780
usually an adjust pin on an LCD supply is for brightness of the CCFL inverter (bottom left of your second picture)... it commands a PWM (or needs a PWM signal, it depends)
the adjust signal + ground should travel around the whole board to the place just under where you have the self and blue rectangular capacitor... try looking at the datasheet of the IC there is under if there is one, if not there is a transistor commanding the oscillator and it should be analog command..
you cal also look at a random CCFL backlight inverter datasheet (one based on a basic inverter) as the adjust signal is pretty standard
@Shrad, I suppose that makes sense, and it turns out only one is adj, the other is the on/off control. I will measure the voltage at that pin tomorrow while adjusting the brightness.
Also real quick, does anybody have an idea how I can measure the output voltage of my CCFL inverter on the power supply board? I know it supplies 6mA, but at what voltage is a mystery as I can't find any info on the transformer.
Registered Member #1526
Joined: Mon Jun 09 2008, 12:56AM
Location: UK
Posts: 216
Got a `scope and ht probe?
edit: Or, use it to charge an ht cap through a known ballast resistor for a known time period (so the voltage is low) to fill it with a known energy. Once you`ve done that, measure the voltage and use:
Registered Member #30
Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706
No, a CCFL inverter won't charge a capacitor because the output is AC. It is also very high impedance, so the voltage depends heavily on the load. Just hook it up and see if it works.
EDIT: I am just going to cut the CCFL inverter off the power supply board, as the on/off and adjustment controls lead to it anyway. It will save the trouble of having to find a new one. There is however an inverter on the LCD panel itself, the model number is U40I008T01, and I can't find any info on it all. I tried using the supplied schematic in the drivers datasheet to find the +, -, on/off, and brightness controls, but was unsuccessful for the most part.. If anybody has any ideas on how I can use the one supplied with the screen that would make life alot easier.. :)
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LCD Screen Power Supply Question
