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787 Electrical Issues w/ iPhone?
Flew my first 787 route on Monday (ORD-IAH) in 5A. Hooked up my iPhone (4s) to charge during the flight and the phone went completely buggy. When trying to use the screen, I wasn't able to click on icons and the screen would flash uncontrollably. When unconnected, I had none of these issues. I kept plugging it in and unplugging it and the performance was consistent.
Anyone else encounter similar issues?
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Flew my first 787 route on Monday (ORD-IAH) in 5A. Hooked up my iPhone (4s) to charge during the flight and the phone went completely buggy. When trying to use the screen, I wasn't able to click on icons and the screen would flash uncontrollably. When unconnected, I had none of these issues. I kept plugging it in and unplugging it and the performance was consistent.
Anyone else encounter similar issues?
Wow!!! I had thought it was the fault of my iPhone 4s. I had the exact problem the other day when I was in BF seats from EWR to IAH. When I was using the power outlet, my phone is very buggy. It turned out that I just used the USB port to charge my iPhone. This must be reported to UA.
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Quote:
Originally Posted by Karlson
When I use Chinese cable/wall plug with an iphone, it happens exactly what happened to you. Might be faulty plug.
Potentially...but this was the first time I'd ever had any issues. Since my flight on Monday, everything has returned back to normal regarding charging the phone.
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This is a normal issue, when using square wave AC power.
Since you can't "Ground" an AC circuit on an airplane (without a really long extension cord ), the AC power you are getting is actually what is called square wave AC. The device thinks it's AC, and it works to charge, but it will cause crazy things on touch screens, and funny grounding issues. Essentially your body via your finger, becomes the ground. It's slightly more complicated, but that is the short answer.
The waves if you were to look at them on an O-scope would not be the nice round analog sine wave you see on regular power on the ground. Instead the wave will appear to be straight 90 degree rise, a flat top, and then a 90 degree drop, flat bottom etc.
You would get the same effect if you use an AC inverter in the cigarette lighter of a car, and plug in your device. Nothing to worry about really - just unplug the adaptor before trying to use the touchscreen...
That is the reason if you use the USB in seat power connection as stated by another post - which is DC (not square wave AC), you would not have those problems related to electrical ground.
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Quote:
Originally Posted by UAgeek71
This is a normal issue, when using square wave AC power.
Since you can't "Ground" an AC circuit on an airplane (without a really long extension cord ), the AC power you are getting is actually what is called square wave AC. The device thinks it's AC, and it works to charge, but it will cause crazy things on touch screens, and funny grounding issues. Essentially your body via your finger, becomes the ground. It's slightly more complicated, but that is the short answer.
The waves if you were to look at them on an O-scope would not be the nice round analog sine wave you see on regular power on the ground. Instead the wave will appear to be straight 90 degree rise, a flat top, and then a 90 degree drop, flat bottom etc.
You would get the same effect if you use an AC inverter in the cigarette lighter of a car, and plug in your device. Nothing to worry about really - just unplug the adaptor before trying to use the touchscreen...
thanks for clarifying! very helpful.
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Quote:
Originally Posted by UAgeek71
This is a normal issue, when using square wave AC power.
Since you can't "Ground" an AC circuit on an airplane (without a really long extension cord ), the AC power you are getting is actually what is called square wave AC.
Square wave AC and earth ground (or lack thereof) are two totally separate issues (or, more accurately, not necessarily related). You can have one without the other.
It would be possible to create sine-wave AC on the 787 (I'm sure the 400Hz power in not square-wave AC). It's just harder ($) to do that. That's why cheaper car units don't make clean sine wave voltages (check out this reference).
Square wave AC and earth ground (or lack thereof) are two totally separate issues (or, more accurately, not necessarily related). You can have one without the other.
It would be possible to create sine-wave AC on the 787 (I'm sure the 400Hz power in not square-wave AC). It's just harder ($) to do that. That's why cheaper car units don't make clean sine wave voltages (check out this reference).
Yes true on all points. Accurately - the ground issue and square wave are not necessarily related, and the quality (clean-ness) of the power is in fact related to $ spent.
The general point, without getting into too much geek speak, was that by touching the screen, you are changing the ground potential more so than if the AC had a real earth ground, and that can cause havoc on the device.
The Conversion of Square wave AC back to DC can also have some interesting effects on electronics - all though the apple branded tiny Wall Charger is quite efficient and well designed - so most EMI should not affect the touch screen.
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Quote:
Originally Posted by UAgeek71
...The device thinks it's AC, and it works to charge, but it will cause crazy things on touch screens, and funny grounding issues...
Quote:
Originally Posted by ralfp
Square wave AC and earth ground (or lack thereof) are two totally separate issues (or, more accurately, not necessarily related). You can have one without the other...
+1 to both of you! And to the OP for posting the question. I took my first 787 ride on Saturday, spent most of the flight working on my Macbook Pro, and was awfully puzzled (and slightly inconvenienced) by the fact that my touchpad would periodically go nuts. It's not a huge problem if you're just entering text, but for graphic arts it's real obstacle! Thanks for providing some background. (I am a physicist, but the ground issue hadn't occurred to me. Duh.)
Followup question for discussion: I've used AC power on other planes, and never experienced this issue -- which came up pretty constantly on the 787. Are we going to find out that, for whatever reason, the 787 has this problem worse than other aircraft?
), the AC power you are getting is actually what is called square wave AC. The device thinks it's AC, and it works to charge, but it will cause crazy things on touch screens, and funny grounding issues. Essentially your body via your finger, becomes the ground. It's slightly more complicated, but that is the short answer.
to both of you! And to the OP for posting the question. I took my first 787 ride on Saturday, spent most of the flight working on my Macbook Pro, and was awfully puzzled (and slightly inconvenienced) by the fact that my touchpad would periodically go nuts. It's not a huge problem if you're just entering text, but for graphic arts it's real obstacle! Thanks for providing some background. (I am a physicist, but the ground issue hadn't occurred to me. Duh.)
