Author Topic: Asus h81t Motherboard shocking me  (Read 1138 times)

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Offline PowerRepo

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Asus h81t Motherboard shocking me
« on: January 30, 2016, 02:27:06 am »
Hi everybody i have a h81t asus mini itx motherboard and a http://www.mini-box.com/19v-8-4A-160-Watt-AC-DC-Power-Adapter power supply for some reason if i touch ground it shocks me this power supply is wired for +19volts on the inner ring and -19volts on the outer rinf  and nc not connected on the center pin i think this is where the priblem is that its sending 19 volts to ground can someone help thanks
 

Offline Rasz

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Re: Asus h81t Motherboard shocking me
« Reply #1 on: January 30, 2016, 09:55:07 am »
no, the problem is buying chinese crap and bad wiring in your house. im guessing its not isolated and there is potential between its ground and AC in the wall
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Offline Tim F

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Re: Asus h81t Motherboard shocking me
« Reply #2 on: January 30, 2016, 10:55:23 am »
Hi everybody i have a h81t asus mini itx motherboard and a http://www.mini-box.com/19v-8-4A-160-Watt-AC-DC-Power-Adapter power supply for some reason if i touch ground it shocks me this power supply is wired for +19volts on the inner ring and -19volts on the outer rinf  and nc not connected on the center pin i think this is where the priblem is that its sending 19 volts to ground can someone help thanks
What are you measuring these voltages in reference to? I.e. when you 'measure 19V on ground' what are you probing with the other multimeter lead?
If you mean that your meter reads +19V when you put the positive probe on the inside ring and the negative probe on the inside ring, and then -19V when you reverse the leads then this is normal. The multimeter doesn't know what is supposed to be ground, that's why you have to connect the negative/ground probe to something to give it a reference. If you connect the leads backwards then the measured voltage will be negative as now the multimeter is using the '+19V' as it's ground reference, and the powersupplies ground looks like -19V compared to it. +/-19V DC isn't really enough to give you a shock on dry skin anyway.

What you need to do is to put your multimeter on AC voltage and connect one lead to real earth (e.g. the earth on a mains outlet, or a metal building water pipe) and the other to powersupply output ground. You should see no more than 30V AC. If you see more than that then there is probably enough leakage between the primary/mains of the powersupply and the output to give you a mild shock. Either that or the electrical wiring in your building is not earthed correctly.
« Last Edit: January 30, 2016, 10:57:51 am by Tim F »
 


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