Tool?

January 31, 2006 9:07 AM

I'm looking for a tool I can use to prevent users from shutting off the computers in the public library.

We just added a new timeout software, and it messes up the program when computers are restarted. Is there anything like a waterbottle cap and duct tape that would look more professional?

posted by madmath to computers & internet (15 comments total)

This isn't going to be immensely helpful, but some computer cases have a key lock next to the power button. If you could retrofit your case with something like that, I think it would do the trick. I'll try to find one online.
posted by shinynewnick at 9:11 AM on January 31, 2006

Also, depending on the operating system, you might be able to change the action when the power button is pushed. With Windows XP, you can set the power button to do something other than turn the system off. Check under Control Panel, Power Options, Advanced.
posted by shinynewnick at 9:15 AM on January 31, 2006

Isn't it the case that, if you hold down the power button for longer than X seconds, the computer just powers off regardless of what the OS says?

If so, the second suggestion won't work very well.

Now, I've never tried this, but a semi-permanent solution may be to disconnect the power button from the motherboard (I assume that's where the cable runs to, I've never followed it...). If you open the case, you should see a cable running from about where the power button is located to somewhere else in the computer. Unplugging either end of it will disable the button.

A little more graceful than a pop-cap and duct tape, but more hassle if you want the button back for whatever reason.
posted by jcruden at 9:34 AM on January 31, 2006

At my former library, we accomplished this by setting the computer to turn off only if the power button was held in for ten seconds (most patrons won't wait that long, and assume turning the computer off is something they're not supposed to do) combined with a little label near the power switch that said something like "please do not turn this computer off, ask a staff member if you need assistance" My library was a little label-crazy but this kept the reboots down to a manageable level.
posted by jessamyn at 9:40 AM on January 31, 2006

Are you willing to perform minor surgery on the computer(s)? This person posting to the Usenet microsoft.public.win2000.general newsgroup has an interesting solution which avoids most of the pitfalls of other workarounds.
posted by mdevore at 9:58 AM on January 31, 2006

Just disconnect the switch.

How do you turn it on later without opening the case?
Easy, there is a 'what to do on power failure' option in most any BIOS nowadays, just set that to turn on your computer.

Then to turn it off you pull the plug, to turn it on you plug it in.
posted by Chuckles at 10:04 AM on January 31, 2006

Most modern PC's have settings in a BIOS screen for advanced power management (ACPI) that gives you some options for actions to be taken when the soft power button is pressed. And see this MS Knowledgebase article for instructions on setting up Internet Explorer in kiosk mode; for Windows XP based machines in public or shared access settings, you may want to look into putting up the free Microsoft Shared Computer Toolkit, which has many additional options for setting up a "public" account with limited capabilities, including removal of the "Turn Off Computer" button from the public account user interface.

Of course, this won't keep the truly determined from reaching around back, and pulling out the power cord, or flipping off the power supply switch, but for controlling those possibilities, you can look into kiosk cases.
posted by paulsc at 10:10 AM on January 31, 2006

Bad idea, according to the link I posted: "One thing that you do NOT want to do is to disconnect the power button, and power on the system by applying AC power, with the BIOS set to power-on upon application of power. This option is intended for power outage recovery for servers. It is a bad idea to disconnect power from the PC as a method of turning it off--don't use a power strip on/off button as an on/off switch. The PC's power supply supplies +5V standby to some parts of the system, including the RTC (the battery is small, and intended for backup during outages). "

'Course, I've known people that always turned on their computers through power-strips, so make of those remarks what you will.
posted by mdevore at 10:10 AM on January 31, 2006

Perhaps an easier method would be to modify your timeout software? What failure is occurring?
posted by odinsdream at 10:13 AM on January 31, 2006

Just unplug the power button from the motherboard. Then it won't do anything.
posted by delmoi at 10:16 AM on January 31, 2006

I think the power button is the least of the problems. Windows can still power down by doing the old Ctrl-Alt-Del.
posted by JJ86 at 10:46 AM on January 31, 2006

I don't think removing power from a PC will do it any harm, as long as it's a sudden off and not a brownout. As long as the power supplies aren't $5 cheapies, they should gracefully handle it. A decent PC power supply is a surprisingly robust beast. They can take a lot of abuse.... and a simple power failure isn't really abuse.

Disconnecting the reset and power buttons from the motherboard, and using a hidden power strip to control power, should be your easiest solution. Make sure you write down where the wires go.. it can be hard to read the labels on the motherboard when it's still in the case. I'd suggest drawing a little diagram and taping it to the inside of the case, because it could be many years before anyone opens the machines again, and you may be long gone.

Most PCs will let you set, in the BIOS, to either power on after a power failure, or return to 'former status'. Either setting should work fine for the powerstrip method. If you don't have either setting in your BIOSes, this idea won't work, so I'd suggest checking that first thing.

Remember to initiate a software shutdown before killing power. It's no big deal for the hardware, but most OSes get unhappy when they can't do their normal cleanup.
posted by Malor at 11:04 AM on January 31, 2006

The control-alt-delete is already disabled.
posted by madmath at 12:28 PM on January 31, 2006

We solved this problem replacing the power button with a magnetic reed switch used in alarm systems. Wire the reed switch to the power button leads and then hot glue or epoxy the switch to the front of the case. The key is practically any strong magnet swept over the front of the case. The client used a 12" piece of broomstick with a rare earth magnet jammed in a hole drilled in the end so it couldn't be easily lost but our magnetic name tags would also work.

The key benift of this approach is the switch is tamperproof and cheap. Those key type switches are expensive and we'd find people would jam gum into the keyhole.
posted by Mitheral at 1:21 PM on January 31, 2006

Many comptuers have BIOS settings to turn the computer on when pressing the spacebar on the keyboard (and it only works for *on*, not *off*). Combining this option with disconnecting the on switch at the motherboard seems to be a good solution.
posted by helios at 3:10 PM on January 31, 2006