Equipment - Viewsonic 4 Computer Monitor 24kV High Voltage Power Supply

I made this power supply by converting a Viewsonic 4 computer monitor into a 24kV DC power supply. It was extremely simple to do.

Close up of the top of the power supply with my fancy connecting and discharging arrangement.

The hinged door for easy access to the inside.

There are two things to make sure of if you do this. The first is to make sure that the monitor is not plugged in at any time. The second is to make sure the monitor is not one of the newer ones that has the green power saving feature that requires that it be plugged into a computer in order to function. If you turn on the monitor, without it being plugged into a computer and you do not get a signal then you may as well not use that monitor.

Once I was sure of these things I opened up the case. There was a thick wire going into the vacuum tube through a rubber suction cup (see diagrams below.) This was the high voltage wire. The cathode ray tube that this suction cup is attached to is a high voltage capacitor. If the monitor has been turned on recently then there may still be high voltage in the capacitor. Make sure the monitor has been off for at least a day before removing the wire. Basically all I did was drill a hole in the case of the monitor and put this wire through it.

For the ground wire I looked to where the power chord entered the monitor. In the power chord there were three wires with different colored insulation on them: black, white and green. Inside the monitor, the end of the green wire was screwed to the chasis, a large sheet of metal that a lot of things were mounted on. So I simply made a hole in this same chasis and screwed my own wire to it. This was to be my ground wire. I then drilled another hole in the case and put this ground wire through it. Done.

Then, as the pictures above show, I got fancy, probably needlessly. I made a fancy arrangement on the side of the monitor (which is now the top of my power supply since it will always sit on its side) for connecting to but also for making it easy to discharge after each use. That's what the balls are for. I also cut up the top of the monitor and added a hinge to make a door for easy access to the interior of the monitor without having to remove the case. Like I said, probably needless.

I measured the voltage using my Fluke 40kV high voltage probe. It turns out that it puts out about 24kV. I tested with the probe tip and ground clip right at the wires coming out of the case as well as with the tip and clip closer to the device under test at the time. Both times the results were around 24kV with no noticable difference.

One thing I didn't do but I should have was to put a large resistor in series with the high voltage output. Because I didn't do this the monitor died after too much sparking during use. You should put at least a 250 kilo ohm, 2 watt resistor somewhere on the high voltage wire before it gets to whatever you're powering. Be sure that when you solder the resistor in place you use thick, round blobs of solder. Sharp points tend to leak charge and will decrease the high voltage you get at the outputs.

Cutaway view of computer monitor before wiring changes.

The wiring after the modifications.

Links

• Advices for Powering a Lifter (by Claude Dupr)