When I was cleaning up my cellar I found my old LCD-Monitor with a broken LCD Panel. I thought it would be a pity to just throw it away, so I thought about what to make out of it. The idea was a large lamp for taking pictures. This is what I needed for it:
LCD-Monitor (of course)
Potentiometer (my has 20Ω)
Resistors 2.2 Ω 3x, 10Ω 1x (depending on the voltage the monitor needs and the resistance of the potentiometer)
LM317 voltage regulator
A piece of perfboard
A 2 pin header with jumper
A 3 pin header for making the potentiometer removable
A piece of Plexiglas with the size of your Monitor
Drill whit the diameter of the potentiometer
Step 1: Take Apart Monitor
First remove the stand. Then use a small screwdriver and push between the two plastic frames. One should come off. If you are not sure how to open your monitor ask Google. Now remove the second plastic frame. In my case I had to push away a piece of plastic. After that remove the cables from the speaker, the buttons and the Backlight. Unscrew the screws at the side and open up the monitor.
Step 2: The Internal of the Monitor
Under the top of the monitor there is a flex cable from the motherboard to the logic board of the LCD panel. Unplug it by pressing the two metal pins together and pull. On the logic board there is a plastic cover. Remove it and unscrew the logic board. At one side there are two metal clips. Bent them away and at the side there are plastic clips. Push them with a screwdriver and the metal frame should come away. Now you can remove the LCD panel and replace it with the Plexiglas. If you want you can put a colored foil between the lamp and the Plexiglas or remove the polarization foils to extend the beam angle. Mount the monitor back together.
Step 3: The Electronics
Now to the back plate. At the back plate there are three boards: the large one is the Power supply and the inverter board, remove all the wires and unscrew it carefully because we need it later. Next there is a smaller board with the VGA and DVI connector on it, the mainboard. You can remove it, because we don’t need it anymore. The third board is the board with the buttons on it, you can also remove it.
Step 4: More Electronics
Now you have to modify the power supply to turn it on without the mainboard and control the brightness of the lamp. In my case there were marks on the board for each connector, so I only had to follow the conductors to locate the CCFL Controller. It was an OZ9910SN so I downloaded the datasheet. There was written that the dimming is analog and it is working with 1.5V-3.5V. So I designed the following circuit to set the voltage, using a LM317 voltage regulator. I calculated the resistance for 1.5V and for 3.5V as you can see in the following pictures. The idea is that when the potentiometer is turned to 0Ω the current flows true R1 and R2. They are in series so the resistance is 4.4 Ω what is about 1.5V. Perfect. If the potentiometer is turned to 20Ω the current is flowing over R1, R2 and P1. They are also connected in series so the resistance is 24.4Ω what is about 3.5V. On other monitors the brightness is might dimmed whit PWM, then you have to make a circuit with a ne555 timer or an op Amp.
Step 5: The Most Electronics :-)
After prototyping the circuit on a breadboard and measuring the output voltage I soldered the circuit to the perfboard and glued the perfboard to the power supply. You also have to drill a hole into the case to make the potentiometer fit through.
Step 6: Reassembly
Connect the potentiometer to the perfboard and mount the power supply back in. Make sure every wire is going his right way and northing makes contact whit the case and remount the back cover. Plug in the wires of the backlight and attach the stand. You can also drill a hole into the plastic covers and remount it but I think it looks better with the metal case.
Step 7: Testing and Other Usage Possibilities
Now you only have to set it on power (if possible the first time over an isolation transformer) and see if it works or not. If it works try to change the brightness by turning on the potentiometer.
Useful usage possibilities:
Of course as a Softbox
As a slide or an X-ray pictures viewer
As a Tracing table
… (Feel free to post other usage possibilities)
Thanks for reading my third instructable (and thanks to my teacher for correcting it)!