If it looks right, plug it in.
That's what happened when someone plug in a 300mA wall plug into a 7" tablet expecting 5V 2A.
I measured the DC out and got 7V. The battery (4V) also got 7V. So, most of the electronics are fried.
But the interesting thing is that the LCD screen come up for a few seconds complaining a low battery condition. So, some thing is still working.
The question is why didn't the wall plug failed open circuit, but end up driving over-voltage. Isn't that unusual?
Is that a regulated 7 V or does it drop under load? That is normal for a lot of wall warts. They might have spec's of 12v at 500ma but open circuit it will measure 15 or 16 volts. You have not convinced me you have a problem with the Tablet yet. Mikek
But the battery (marked 4V) also measured 7V. It drops slightly when the screen turn on for a few seconds, complaining that the battery is dieing.
The Li batt should say 3.7V and not 4V. There are 7.4V tablet batteries:
Yes, it's "BJ8.4V". I missed the whole thing before the dot. So, is there a boost converter inside for the battery? Perhaps i just need to find the right power plug for it.
That depends on the power adapter. I'm not seeing any charger ICs working down to 7V for two-cell LiPo, they all require 8V minimum.
It's supposed to be 5V 2A input to the tablet. This 5V 300mA is probably not the original or the right plug. It's made by Nokia, while the tablet is SVP.
300 mA isn't enough current.
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