Found the time to build my cooling system today (yay!)
Cabinet rear panel, 3 120mm fans, fan grilles; some fan extention wires (which I ended up not using); the timer board; a 12v relay (for isolation from the PC); a 1.5A 12v wall wart from Radio Shack, and a DC power jack for it.
Initial layout done (need to make sure it'll all fit...):
Masking tape is great for plotting things out on! Here, the layout is all drawn out (lay it down, and trace it with a pen - works for me!),
and, holes all plotted out. The screw holes for the fans were plotted by the 'screwdriver thru the holes' method.
The holes for the timer board, I had to do by careful measurement, because I'm mounting it 'backwards.' Reason: I want the adjustment pot to be accessable from outside of the cabinet.
Finding the center point for the fan holes, that's the easy part: just use a straightedge (or, a handy DVD case), and make an X off of the screw holes.
How to make big holes? Why, a Dremel (of course!), with the circle-cutting attachment:
All holes drilles and cut:
Never mind the naked areas on the panel - they've been there for years (they're from holesaw cutting the original
cable holes, and are hidden by the equipment in the cabinet. But, I'll touch those up with a Sharpie when I'm doing my new holes, too.)
View from outside, with the fans, timer board mounts, and power jack mounted:
And, a pic of the fully-assembled (and, running, too!) setup:
Note the second 1.5" hole - this was cut to replace the older top 1.5" cable hole (lost to a fan.) Need two holes, due to the sheer amount of cabling that passes thru the rear panel.
The timer board, I mounted with some 8-32 screws and nuts I scrounged up at the house (3 nuts per screw, creating a standoff mount.)
There's a extra hole in the panel, right behind the timer board, allowing access to the adjustment pot (in case I need to change it from its current 10 minute delay.)
Now, I just need to find the time to shut down the box, and put the rear panel back on.
I did need to re-read the board's wiring diagrams, after the fans were initally non-functional:
I hadn't realized that the relay's load side is electrically isolated from the board itself.
Hence, the wire that you see passing over the board - that one connects the fans' negative leads to the power jack's negative terminal.
The yellow wire jogging up the left side, that runs from the power jack's + terminal to the NO relay connection (fan + is connected to COM.)
As for the relay (which is wire-tied to the bottom of the lower (middle) fan): that was procured from K40 (they make hardwire radar detectors.) We get that relay from them at the dealership to install systems into our newer cars (no real load-capable ignition-switched power supplies.)
Really, really useful little thing, it is.