It should be noted that this works ONLY with this power supply (the 1200W HP Hot Plug 1U 12V DL580G5 Power Supply 440785-001)
Information on other power supplies can be found on the links below.
Step 1: A Little Background
A couple of years ago I got interested in the whole DIY-Christmas-Lights-sync’d-to-music thing. I did some research and found the controller I was happy with and set about it.
For my first attempt I created a simple Mega tree using 16 strings of (50 pixels-each) 12volt WS2811 pixels, an Advatek PixLite16 controller and a modified ATX computer power supply. This worked fine for the simple 800 pixels I was using but knew I would have to find a better, more powerful supply for this year’s (2015) show.
Still thinking only about ATX supplies, I was surprised when I found a very low-cost alternative. A 12volt 1200W(!) power supply for less than $30(US). The problem? No paperwork. No pin-out diagram. No On-Off switch. Just plugging in the power cord did nothing. The HP website was practically useless, I could find plenty of information about the file server the PS is designed for, but no information on the PS itself.
Searching the web lead to several only slightly helpful sites and YouTube videos from the Radio Control helicopter groups. The problem was that the RC’s run on 24volts, and I needed 12volts. Eventually I found this article which lead to this article, and I found this video on YouTube along with many others.
Step 2: Making It Turn On
I had to wade through a lot of information to figure things out, especially since it ended up being such a simple fix.
So, to save everyone else a lot of reading and watching of various videos, I decided to make this short Instructable.
To make a long story short (too late!), all that is really needed is to solder a resistor 330 – 1k Ohm resistor between pads #33 and #36 and I should have plenty of power for my Christmas lights. (Only pads #33 and #37 are labeled, but you should be able to figure it out easily enough.)
(Alternatively, you could solder a toggle switch inline with the resistor to give you an on-off option rather than just unplugging it.)
The 2 large pads (#51 and #64) are for the -12v and +12v outputs, respectively, so just solder your output wires there.
Step 3: 120vAc Vs 240vAC Input
Now a word about input voltages: This particular PS uses a standard PC power supply socket on it (any power supply cord should work) and has an automatic voltage range sensor. Now the tricky part… at 110vAC to 120vAC the PS will only supply 900 watts and 200vAC to 240vAC input is required to get the full 1200 watts out. This means that the standard power cord will need to be modified if you intend to use it at 1200 watts. If you are not experienced with working with high voltages, DO NOT ATTEMPT TO DO THIS YOURSLEF! (I assume NO RESPONSIBILITY if you do it anyways and get killed or burn down your house!)
If you do decide to attempt this modification, leave the female end of the cord alone and change out the male 120v15amp end to a 220v20amp. (sorry, it's upto you to figure out which wire goes where)