COOL IT! Installing the cooling fan ATARI forgot. by Anthony M. Borbely Anyone who owns a 520STFM or 1040STF knows how much heat the built-in power supply gives off. Long hours of use can make this a real problem. The addition of more memory places a further load on the power supply, producing even more heat. I decided to add a cooling fan to my ST to solve the problem. After the installation, I let my machine run for 12 hours as a test, the result being that my ST never even 'warmed up'. I've had no problems in 3 months of daily use. BBS Sysops will especially benefit from this installation to their STs. It is not a difficult job, but some handiness is required, as this is not a 'plug in' job. First, you have to obtain a suitable fan, preferably a 'computer cooling fan' between 2" and 3" in size. A 3" fan is a snug fit, but will fit. A 2 1/2" fan would be better. I used a 3" brushless 12VDC, low noise, cooling fan (Radio Shack #273-243). Tools needed: Phillips screwdriver, Needle nose pliers, electric drill, soldering iron, mounting screws. Installing the fan requires complete disassembly of your ST as you will mount the fan to the motherboard's RF shield. Disassembly is as follows: 1) Disconnect all power and peripheral cables. Place your ST face down on a towel, and remove all Phillips screws from the bottom of the case. Turn your ST face up. 2) Carefully remove the top half of the case. Be careful around the disk drive eject button. 3) Disconnect the keyboard from the motherboard. Use needle nose pliers to carefully pull the connector up. Lift out the keyboard. 4) The fan will mount between the power supply and disk drive covers. Use a pen or marker and outline their respective locations on the main RF shield. 5) Remove the screws of the power supply shield and remove the power supply. Carefully disconnect the power supply connector from the motherboard. This has 5V, 12V and ground lines (red, blue, & black wires). 6) Remove the disk drive shield, and remove the drive. Again, carefully disconnect the cables. Make note how they are connected. 7) Remove the screws holding the main RF shield assembly. There are several 'twist holds' that will require straightening with the needle nose pliers. 8) Remove the RF shield. If it doesn't want to come, check that you've undone all holds. Be careful around the ports in the back, as things tend to get stuck there. Edges are sharp, so be careful! So far so good. You've got the RF shield in your hand. In order to exhaust the air from the ST, you got to mount the fan blowing upward. You also have to drill fan mounting holes, and holes (or hole) that the fan can draw the air through. Continue as follows: 9) Place the fan on the RF shield between the outlines of the power supply and disk drive that you marked earlier. Mark the fan's mounting holes. Drill suitably sized holes for the mounting screws. 10) Determine the diameter of the hole the fan will draw through. Draw this on the RF shield. You can then use a hole cutter to cut out this hole. It's much easier to drill a pattern of holes over this area. 11) Mount the fan to the RF shield. Be sure to mount the fan so it blows upward. (It won't be forcing dust into your machine this way.) 11) Reinstall your RF shield into your ST. Replace all holding screws, and give those 'twist holds' a bit of a twist. 12) Reinstall the power supply (don't forget the mounting screws), but don't reconnect to the motherboard. This is where you will connect the fan. The connector has 5V, 12V and ground (black) wires. 13) Plug in the power cable, turn on the power supply. BE CAREFUL! YOU ARE NOW LIVE! Use a volt-meter (if available) to determine which lines are 5V/12V. Or, you can just test connect the fan's wires to determine the proper connection. A DC fan is polarity sensitive. If nothing happens, reverse the wires and try again. Make a note of which way to connect the wires. Shut off the power. 14) You can remove the 12V and ground wires from the connector by pressing in the small metal tabs with a screwdriver and pulling them out. At this point I just cut the fan's wires to length, stripped back about 1/2" of the insulation, and soldered them to the appropriate connector, which was then snapped back into its place in the connector. You can do the same, or use jumpers to connect to the power supply wires. 15) After connecting the fan, turn on the power supply. See that the fan is working properly. Listen for vibrations, the fan mounting screws may need adjustment. 16) If everything seems OK, reassemble your ST in the reverse order of disassembly: -reconnect the power supply to the motherboard -reinstall disk drive and its cables -replace power supply and disk drive shields -replace keyboard and reconnect to motherboard 17) At this point, you may want connect your monitor and boot a disk to check you haven't forgotten something. If OK, replace the top cover, and replace the bottom case screws. Fan installation completed! You now have an ATARI ST which will run cooler and undoubtedly last longer. If you're running a BBS... especially so. Hope all who undertake this modification have no problems. If you take your time, follow the instructions, and standard precautions regarding static etc, you should have no problems.