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MK 802 III TV stick rebooting power problem(SOLVED)

PostPosted: Mon Dec 30, 2013 3:54 am
by Hans
I know several users have complained about spontaneous reboot of their device.
I have made some power measurements and here are my results and possible solution for any spontaneous reboot
The actual current I measured varies from boot-up current which peaks at 509 MA to idle current of approx. 200 MA to 650 MA at peak with some applications activated
All measurement were taken with an inline low resistance MA digital meter.

In an ideal world one would say, a 1Amp 5V rated USB wall power source should work.
That is right, provided the power USB cable has a very low resistance which provides no drop in voltage at the MK802 III input terminals.
My MK802 III needed a minimum of 5.2V at the device input terminals for it to boot-up properly .

Most USB power or extension cables are made of very thin and flimsy wiring hence the culprit. Ohms law tells us if the USB power wire has a resistance of 1 Ohm at 5V , we will see, at 500MA, a drop of 0.5 v delivering only 4.7 V at the device power terminals, just enough for an eternal boot-up process.

SUGGESTIONS
You either get a slightly higher voltage power source to accommodate the voltage loss of the cable ,to be save, with a minimum of 2Amp rating , remember we need 5.2 V at the device terminal.
Or better yet, get yourself or make yourself a short USB power cable with a minimum 18 AWG gauge wire.
With the latter solution you will find that most USB ports on a TV can provide plenty of current to deliver a operational voltage (5.2V) at the device input.

Re: MK 802 III TV stick rebooting power problem(SOLVED)

PostPosted: Sat Feb 15, 2014 11:37 am
by wololo
This is a pretty recurring issue indeed, I remember mentioning it (and the solution) in the very early days of the mk802 III: http://makesmarttv.net/your-computer-on ... the-cause/