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Old July 14th, 2012, 04:25 PM   #24 (permalink)
Mrhelper
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Quote:
Originally Posted by spoutman View Post
I had the same problem. Factory charger went bad. It was a switching charger, got one on ebay and it will start charging, red light on, then in a few seconds got a blinking white light. unplugged it and plugged it back in, charging light came, same thing again. I decided to play with it. I plugged it til it went white blinking light, then unplugged it again, started charging. Did this til I got about 25% charged. My theory is that it has to be a switching charger and I was simulating that by switching it manually. tells me that you have to have a switching charger like the one that came with it.,
You are probably correct about the need to use a charger with the same specs as the original. The problem actually appears to be due to inadequate voltage regulation properties of certain aftermarket supplies, where the voltage levels output by certain chargers drop too low under load. I've seen several reports about this same problem.

I worked with another user on this problem and he discovered while monitoring with a volt meter that the aftermarket supply he tested did not maintain adequate voltage levels. The charging circuit apparently requires a well regulated voltage and does not tolerate drop offs. When the voltage drops below a certain threshold, the battery charging circuit detects that, and opens, where you then see the error condition indicated by the flashing power light. When you manually disconnect/reconnect the charger, the charging circuit resets and tries to charge again. The voltage again drops below the required threshold, and after a specific time at the lower voltage (which I recall to be about 5 minutes), the charging circuit again disconnects.

A good switching-mode power supply of the appropriate specs apparently provides a steady well regulated voltage that does not drop below the threshold, so the charging circuit continues to operate without interruption.

Note that the "switching" part of the power supply refers to the method used to regulate the voltage, and not to any switching of the output voltage/current. A switching-mode supply does not turn the output power on and off, but maintains it at a steady voltage level. Again, when you unplug and plug back in the charger, you are just resetting the charging circuit in the tablet which allows it to charge for a short while until the logic determines that the voltage level is inadequate, and disconnects the power from the battery.
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Last edited by Mrhelper; July 14th, 2012 at 04:49 PM.
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