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Forum topic by InstantSiv posted 03-23-2016 03:56 AM 493 views 0 times favorited 8 replies Add to Favorites Watch
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InstantSiv

259 posts in 1058 days


03-23-2016 03:56 AM

My tablet wouldn’t turn on so I troubleshooted it and came to the conclusion that it was the power cable that broke. I took a reading with a multimeter and the voltage was fluctuating between 0.06 volts and 2.86 volts. It’s suppose to output 12 volts, time for a new power cable.

The power cable has a box in the middle, which I’m assuming is the transformer. That’s suppose to convert AC to DC right? Here’s the question… the multimeter was showing a fluctuation in voltage… Is that transformer failing to convert the ac to DC and letting ac thru?


8 replies so far

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TopamaxSurvivor

17669 posts in 3138 days


#1 posted 03-23-2016 07:12 AM

Hard to tell. Depends on the quality of the meter and the settings.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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MalcolmLaurel

269 posts in 1086 days


#2 posted 03-23-2016 10:59 AM

Doubtful it’s “letting AC through”. More likely it’s a broken wire. Power supply wires tend to break at the point where the wire exits the strain relief, either at the case or at the plug end. See if the voltage changes when you flex the wire at those points.

-- Malcolm Laurel - http://MalcolmLaurel.com

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InstantSiv

259 posts in 1058 days


#3 posted 03-23-2016 03:17 PM


Hard to tell. Depends on the quality of the meter and the settings.

- TopamaxSurvivor

Only the best


Doubtful it s “letting AC through”. More likely it s a broken wire. Power supply wires tend to break at the point where the wire exits the strain relief, either at the case or at the plug end. See if the voltage changes when you flex the wire at those points.

- MalcolmLaurel

I didn’t see any changes when manipulating the cord. The voltage was fluctuating very consistently between 0.06 volts and 2.86 and the pace was very consistently too… would cord damage act in this way?

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bonesbr549

1176 posts in 2530 days


#4 posted 03-23-2016 05:46 PM

power cords fail with regularity. If you are like me, you have a lot of cords around. Look for another transformer that has the same dc voltage out and amps and polarity to test. I’ve had several die and scavaged replacements. The big thing is making sure that polarity is the same easy way to tell is on the ps you will see a + & a – and either an arrow or a line and a semicircle surrounding one side that will indicate polarity. Something else to keep in mind if your battery is totally shot, it will not come on at all. I know I’ve got one, thats down to shutting down if its not constantly plugged in to wall power. It will degrade to the point soon and I will have to breakdown and buy a batt.

From you explanation it does appear the ps may be dying.

I hate buying batts/power supplies for laptops, cost a freak’n fortune.

Good luck.

-- Sooner or later Liberals run out of other people's money.

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TopamaxSurvivor

17669 posts in 3138 days


#5 posted 03-23-2016 06:03 PM

Most digital meters see ghost voltages under many conditions. Most likely what you are seeing. An analog meter would probably read “0”.

-- Bob in WW ~ "some old things are lovely, warm still with life ... of the forgotten men who made them." - D.H. Lawrence

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ChrisK

1809 posts in 2544 days


#6 posted 03-23-2016 06:49 PM

The input to the tablet should be DC, make sure the meter is on DC

A non RMS AC meter will not show the correct voltage unless the voltage wave is a pure sine wave. So any noise on the DC will so as an AC voltage, but you will not really know what it is.

-- Chris K

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patcollins

1420 posts in 2328 days


#7 posted 03-24-2016 12:20 AM

It is most likely supposed to be 5 volts DC, is it a mini-usb or micro-usb connector that attaches to your tablet?

Do you really mean tablet or laptop? I have never seen a tablet take any sort of charger that wasn’t a cell phone charger.

View InstantSiv's profile

InstantSiv

259 posts in 1058 days


#8 posted 03-25-2016 02:21 AM


power cords fail with regularity. If you are like me, you have a lot of cords around. Look for another transformer that has the same dc voltage out and amps and polarity to test. I ve had several die and scavaged replacements. The big thing is making sure that polarity is the same easy way to tell is on the ps you will see a + & a – and either an arrow or a line and a semicircle surrounding one side that will indicate polarity. Something else to keep in mind if your battery is totally shot, it will not come on at all. I know I ve got one, thats down to shutting down if its not constantly plugged in to wall power. It will degrade to the point soon and I will have to breakdown and buy a batt.

From you explanation it does appear the ps may be dying.

I hate buying batts/power supplies for laptops, cost a freak n fortune.

Good luck.

- bonesbr549

Unfortunately the power cord is designed in such a way that I cannot use an older cord. They want $70 for an oem cord! $30-$40 for an off brand of good quality… I went with the cheap Chinese ones for $15.


The input to the tablet should be DC, make sure the meter is on DC

A non RMS AC meter will not show the correct voltage unless the voltage wave is a pure sine wave. So any noise on the DC will so as an AC voltage, but you will not really know what it is.

- ChrisK

It was on DC. So the fluctuation could be noise? Interesting…


It is most likely supposed to be 5 volts DC, is it a mini-usb or micro-usb connector that attaches to your tablet?

Do you really mean tablet or laptop? I have never seen a tablet take any sort of charger that wasn t a cell phone charger.

- patcollins

Surface Pro 3. I know it’s not technically a tablet, it’s an actual full computer but it’s in a tablet form so that’s what I call it. The charger outputs 12v.

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