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Fanfold Paper
Posts: 17
Registered: ‎10-09-2011
Location: San Francisco
Views: 266
Message 11 of 11

Re: Lenovo function keys repeatedly self-activate in PC games

Ok, I found out what the problem was:  the power source.     I ordinarily use a car 12 v outlet power supply with the Lenovo, (ie. external battery), and apparently when the Lenovo suddenly sucks in more power, presumably more than the external battery and power supply can immediately handle, the Lenovo interprets the transient loss of power as being unplugged, so the Lenovo cycles between display presets (external power vs. internal power).     This causes the symptoms I previously noted:   beeping to indicate the changeover in power source and a brightness display reset.


So the Lenovo function keys and associated app itself was operating normally.    Nor was the problem the Logitech app.   The constant here was which app caused either browser refreshes, heavy video card useage, or simply sucked more power.


The reason games activated this mode predictably, and repeatedly, was because the higher video card power demands they had stretched the available power from the external source to its limit very frequently.    This would then cause a switchover between external power supply to internal power supply, along with a beep and display brightness reset.   I also noticed also the opening browser pages also predictably caused a surge in power consumption, and hence the beeping and brightness reset with that as well.


Once I identified the problem, verifying it was easy:  I just switched to a regular wall outlet for a power source and the problem disappeared for all uses.   Switching back to car battery caused the problem to reappear.     I recharged the car battery and it was "good" for only about 2 or 3 hours before it began to get flaky again.   Starting the engine of the car, and hence running the alternator, also solves the problem.


Interestingly, once a page has fully loaded, the power consumption seems low enough that the Lenovo automatically switches back to the external source, causing another beep and brightness reset.   That's why there was so much annoying beeping:  the power source was cycling back and forth between internal and external batteries.    It was beeping going into and out of power surges.    


The fact the power supply remained marginal for a long time is what made it so confusing, as at some times it would be ok and others it would go into a fit of beeping and brightness resetting.    It all hinged on power consumption, and typically it seemed that video processor power demands are what caused it to bounce back and forth between internal and external power supply.    And as previously noted, the constant was power consumption:  hence video games and browsing refreshes exacerbated the problem, and often initiated it.


It's not clear to me though whether it was entirely just the external battery getting drained somewhat or whether there is also some minor design flaw in the transformer-power supply that connected to the car's 12 v source.    Since the power supply is supposed to deliver 20 volts or so to the Lenovo, that would mean it has to step up the car voltage, and thereby dilute the current output of the battery, right?   Whatever... the main solution here is just to ensure the external battery is fully charged or run the car while operating the Lenovo,  or of course,  run it on wall outlet power.


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