Battery Drain Mystery

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I have in my home a Microsoft wireless keyboard which uses 3 AA batteries. It transmits to a nearby receiver which is connected to a USB port on the computer. When the keyboard was new, the batteries would last for 7 or 8 months. For some strange reason, I'm now changing them monthly.
Recently, I was away for a week and the system was completely shut down. When I returned and booted up, the keyboard was lifeless. I tested the batteries, and they tested completely and totally drained on my meter. That's unusual, because they usually test just weak when I replace them. So, while I was gone and the system was off, something drained the batteries completely.
At first, I assumed it was the keyboard, so I replaced it with another one of the same model, an older one that I still had on hand. Same result, one month. Does this make sense to anyone? Thanks.
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maybe a stuck key that causes the keyboard to constantly emit the IR signal? Or something pressing a key.... something laying on the KB? Or dirt/crud causing leakage that makes the KB emit the IR signal constantly. Idea;try using a digital camera to view the IR emitter to see if it's on when there's no keys depressed. Press a key to see what happens that way,too.
Maybe you should switch to those pre-charged NiMH rechargeables. They hold their charge much better than ordinary NiMH cells. Then you can recharge them every so often and not buy so many alkaline cells.
as a last resort,you could clean your KB in the auto dishwasher(alone,not with dishes..) and dry -thoroughly- with a hair dryer. use a gel detergent,not the abrasive powder detergents.
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Jim Yanik
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er.org:

Good idea, My camera and digicam sees IR, that is how ive tested remotes that were dead.
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How is this done? I just now tried pointing my camera at the keyboard and hitting some keys. I didn't see any change in the display.
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Many of them are RF (radio). There is no IR to see. All I can think of that would affect both your current as well as the older replacement keyboard are leaky capacitors that cause more current drain than the design called for. If that's it, it would be age related rather than usage related. Or, as others said, someone places something on your keyboard that presses a key continuously. You probalby would have noticed that. Good luck.
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It is old, maybe 7-8 years, and you're right, it is RF. I should have realized that. I should probably get a new one, but I've yet to see one with a special key assortment/selection that I like as much. Plus, the Windows 7 drivers work well.
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Rf ok , it wont work sorry I was thinking an IR led. could it be transmitting continously from a stuck key, maybe a real cleaning could help.
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you have to find where the IR port is. Should be a dark plastic window somewhere,most likely on the back edge of the KB.
You can check your camera's IR response with a TV remote. If you can't see the TV remote's LED with your camera,then the camera has a filter that blocks IR,and will not work for the keyboard test.
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MOST current cordless keyboards are RF, not IR
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You can buy an ir detector for a few dollars at any electronics parts store. It's basically a business card with a little ir sensitive patch in the middle that glows red when IR hits it.
http://www.mcmelectronics.com/product/DISTRIBUTED-BY-MCM-72-6772-/72-6772
You can probably find it cheaper than this example. Maybe try ebay...
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snipped-for-privacy@dog.com wrote:

I bought one of those at Radio Shack 10+ years ago. Very handy. I don't think Radio Shack sells them anymore, it was too good a product so they stopped carrying it.
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wrote:

It didn't use batteries, so why sell it?
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snipped-for-privacy@snyder.on.ca wrote:

Exactly!
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Rechargeable batteries are not a good choice for his keyboard because it uses three cells. If he leaves the rechargeable cells in the keyboard until it no longer works, one of the three cells will be reversed and ruined most of the time.
Some devices are designed to use rechargeable cells. They shut off when the voltage drops to around 1.0 to 1.1 volts per cell. Devices that use just one or two cells can not reverse cells. -- I don't understand why they make gourmet cat foods. I have known many cats in my life and none of them were gourmets. They were all gourmands!
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Ron P wrote:

Hi, It may not be KB problem.
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The KB is the only device connected to the batteries and is solely responsible for battery drain. Like it or not, it's time to switch brands.
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AZ Nomad wrote:

Hi, Keep in mind KB is two way device. I mean it is I/O device. Mostly input to the system but output from system to KB as well.
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If no keys have been pressed after a while, it should be asleep.
Leave it to microsoft to design a keyboard whose sleep timer is disfunctional. You can set it next to your windows PC whose monitor fails to shut off 20% of the time. Creating a timer and reliably counting down to turn off a monitor is beyond microsoft's technical skills. I wouldn't expect them to be able to do it on a keyboard either.
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Yup... Your computer fails to "shut off" by going into the sleep mode because some update is processing and interrupting that process midstream would corrupt files and settings on your system that you would not be able to recover from without a wipe and reinstall...
~~ Evan
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AZ Nomad wrote:

Or maybe they changed windows so it doesn't let the keyboard sleep right anymore. You know, one of those "auto-updates" windows is so fond of.
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