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Trackpad instability while MacBook is charging
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D.M. Procida
Jul 25, 2021, 12:50:59 PM7/25/21
to
This is something I first noticed years ago, but I haven't seen anyone
else mention it.
If I use two fingers to scroll using the trackpad, when the machine is
running from the battery power, it behaves as expected.
When it's running from the charger, the scrolling is flickery and
unstable, and also jumps from side to side. All I need to do is place
two fingers stationary on the trackpad and the window (e.g. in a web
browser) will flicker left and right, up and down, and zoom in and out.
It's inconsistent though - it doesn't always do it.
It's a MacBook Pro 2013.
Daniele
else mention it.
If I use two fingers to scroll using the trackpad, when the machine is
running from the battery power, it behaves as expected.
When it's running from the charger, the scrolling is flickery and
unstable, and also jumps from side to side. All I need to do is place
two fingers stationary on the trackpad and the window (e.g. in a web
browser) will flicker left and right, up and down, and zoom in and out.
It's inconsistent though - it doesn't always do it.
It's a MacBook Pro 2013.
Daniele
nospam
Jul 25, 2021, 1:43:45 PM7/25/21
to
In article
<1pcvb8x.5jwdog1moqewtN%real-not-anti...@apple-juice.co.uk>,
that's usually due to mains power fluctuations.
i was once using seat power on an airplane and the cursor was jumping
all over to where it was not usable. no issues when using battery or on
land.
try a good ups and/or a different power adapter.
<1pcvb8x.5jwdog1moqewtN%real-not-anti...@apple-juice.co.uk>,
i was once using seat power on an airplane and the cursor was jumping
all over to where it was not usable. no issues when using battery or on
land.
try a good ups and/or a different power adapter.
Mark
Jul 25, 2021, 4:07:30 PM7/25/21
to
Alan B <alanrich...@nospamgmail.com.here> wrote:
> I can’t say I’ve noticed that but when my 2017 MacBook Air is charging , I
> sometimes get a slight tingling feeling when using the trackpad. I think
> this tingling effect has been mentioned before in this group?
>
Yes, I mentioned it a few(?) months ago. Funnily enough, just felt it a few
times last night (not the trackpad - just touching the case).
--
Cheers ... Mark
> sometimes get a slight tingling feeling when using the trackpad. I think
> this tingling effect has been mentioned before in this group?
>
Yes, I mentioned it a few(?) months ago. Funnily enough, just felt it a few
times last night (not the trackpad - just touching the case).
--
Cheers ... Mark
Liz Tuddenham
Jul 26, 2021, 3:25:57 AM7/26/21
to
sensitive way of checking whether it is 'live'; it is also the safest
way because if you receive a serious shock, the direction of muscle
contraction will pull you away from it.
An old-fashioned neon mains tester (not one of the modern transistorised
ones) can also be used as an indicator if the voltage on the surface is
higher than 120v. A piece of cooking foil laid on the surface and
touching the screwdriver blade will make the test more sensitive.
If you want to add an earth connection to stop the tingling and prevent
the trackpad problems, most of the ports will have at least one
connection to the chassis of the machine which you can connect to earth.
Make sure you don't accidentally earth one of the other pins first,
otherwise the 'tail will wag the dog' and put the unwanted voltage
between the pin and chassis.
The wrong way to tackle the problem is to connect yourself to the
chassis of the machine. You will both be 'live', so there will be no
potential between your fingers and the trackpad; your extra capacity to
earth (or your contact with earth) will also reduce the voltage on both
of you. However, it is a generally bad idea to make yourself into the
earthing conductor for something that you already know is leaking
current from the mains.
The correct way to tackle the problem would be to put a 3-core lead on
the power supply and connect the earth wire to the negative side of the
low voltage output. It's not the sort of thing you should attempt
yourself unless you have the appropriate level of electrical knowledge
(and it will invalidate the guarantee and possibly your house
insurance.).
You could try reversing the live and neutral in the mains plug and see
if that reduces the problem or you could just buy a better power supply.
--
~ Liz Tuddenham ~
(Remove the ".invalid"s and add ".co.uk" to reply)
www.poppyrecords.co.uk
Liz Tuddenham
Jul 26, 2021, 7:26:50 AM7/26/21
to
Alan B <alanrich...@nospamgmail.com.here> wrote:
> Liz Tuddenham <l...@poppyrecords.invalid.invalid> wrote:
> > Mark <captai...@gmail.com> wrote:
> >
> >> Alan B <alanrich...@nospamgmail.com.here> wrote:
> >>> D.M. Procida <real-not-anti...@apple-juice.co.uk> wrote:
> >>>> This is something I first noticed years ago, but I haven't seen anyone
> >>>> else mention it.
> >>>>
> >>>> If I use two fingers to scroll using the trackpad, when the machine is
> >>>> running from the battery power, it behaves as expected.
> >>>>
> >>>> When it's running from the charger, the scrolling is flickery and
> >>>> unstable, and also jumps from side to side. All I need to do is place
> >>>> two fingers stationary on the trackpad and the window (e.g. in a web
> >>>> browser) will flicker left and right, up and down, and zoom in and out.
> >>>>
> >>>> It's inconsistent though - it doesn't always do it.
> >>>>
> >>>> It's a MacBook Pro 2013.
> >>>
> >>> I can’t say I’ve noticed that but when my 2017 MacBook Air is
> Very useful and potential life saving advice - thanks. I remember being
> taught about the back of the fingers ‘trick’ when I worked for a well
> known but now defunct Telecoms/Electronics company in the 80s.
>
> So might some poor electrical connectivity explain Daniele’s problem?
I expect the device isn't supposed to be earthed and there is no
provision for an earth wire. With power supplies like this there are
usually capacitors between the output of the power supply and the mains.
They are there to 'earth' high frequencies, which would otherwise
radiate as interference from the equipment, by shorting them to the
mains (which looks like 'earth' to high frequencies).
These capacitors inadvertently pass a small current from the mains onto
the output. It is a most unsatisfactory arrangment but has come into
general used so that items can be sold in countries where earth
connections aren't provided.
There are very strict limits on how much mains current is allowed and
the types of capacitor that can be used. If the capacitor breaks down,
the output will be connected directly to the mains, so two in series are
often used to give a degree of redundancy. If one of the pair breaks
down, that would give rise to excessive current, so tingling might be a
warning sign that the redundancy has been compromised and something more
serious is about to happen.
> Liz Tuddenham <l...@poppyrecords.invalid.invalid> wrote:
> > Mark <captai...@gmail.com> wrote:
> >
> >> Alan B <alanrich...@nospamgmail.com.here> wrote:
> >>> D.M. Procida <real-not-anti...@apple-juice.co.uk> wrote:
> >>>> This is something I first noticed years ago, but I haven't seen anyone
> >>>> else mention it.
> >>>>
> >>>> If I use two fingers to scroll using the trackpad, when the machine is
> >>>> running from the battery power, it behaves as expected.
> >>>>
> >>>> When it's running from the charger, the scrolling is flickery and
> >>>> unstable, and also jumps from side to side. All I need to do is place
> >>>> two fingers stationary on the trackpad and the window (e.g. in a web
> >>>> browser) will flicker left and right, up and down, and zoom in and out.
> >>>>
> >>>> It's inconsistent though - it doesn't always do it.
> >>>>
> >>>> It's a MacBook Pro 2013.
> >>>
> taught about the back of the fingers ‘trick’ when I worked for a well
> known but now defunct Telecoms/Electronics company in the 80s.
>
> So might some poor electrical connectivity explain Daniele’s problem?
I expect the device isn't supposed to be earthed and there is no
provision for an earth wire. With power supplies like this there are
usually capacitors between the output of the power supply and the mains.
They are there to 'earth' high frequencies, which would otherwise
radiate as interference from the equipment, by shorting them to the
mains (which looks like 'earth' to high frequencies).
These capacitors inadvertently pass a small current from the mains onto
the output. It is a most unsatisfactory arrangment but has come into
general used so that items can be sold in countries where earth
connections aren't provided.
There are very strict limits on how much mains current is allowed and
the types of capacitor that can be used. If the capacitor breaks down,
the output will be connected directly to the mains, so two in series are
often used to give a degree of redundancy. If one of the pair breaks
down, that would give rise to excessive current, so tingling might be a
warning sign that the redundancy has been compromised and something more
serious is about to happen.
Theo
Jul 26, 2021, 7:52:36 AM7/26/21
to
Liz Tuddenham <l...@poppyrecords.invalid.invalid> wrote:
> I expect the device isn't supposed to be earthed and there is no
> provision for an earth wire. With power supplies like this there are
> usually capacitors between the output of the power supply and the mains.
> They are there to 'earth' high frequencies, which would otherwise
> radiate as interference from the equipment, by shorting them to the
> mains (which looks like 'earth' to high frequencies).
On the Magsafe chargers, the cable that has a mains plug on one end and the
> I expect the device isn't supposed to be earthed and there is no
> provision for an earth wire. With power supplies like this there are
> usually capacitors between the output of the power supply and the mains.
> They are there to 'earth' high frequencies, which would otherwise
> radiate as interference from the equipment, by shorting them to the
> mains (which looks like 'earth' to high frequencies).
'duckhead' that goes into the charger is earthed, and that will cause the
Macbook chassis to earth. The 'duckhead' with an integrated UK plug isn't
earthed. If the OP is using a non-UK plug via an adapter, or a UK plug in a
non-UK socket, there is the chance the chassis isn't earthed. I can notice
the difference between earthed and non-earthed with the slight tingle.
> There are very strict limits on how much mains current is allowed and
> the types of capacitor that can be used. If the capacitor breaks down,
> the output will be connected directly to the mains, so two in series are
> often used to give a degree of redundancy. If one of the pair breaks
> down, that would give rise to excessive current, so tingling might be a
> warning sign that the redundancy has been compromised and something more
> serious is about to happen.
https://www.reddit.com/r/apple/comments/9evrtz/uk_3pin_macbook_plugs_not_grounded/
Moral of the story: use the UK mains cable and don't use travel adapters.
Theo
Graham J
Jul 26, 2021, 8:05:10 AM7/26/21
to
Liz Tuddenham wrote:
[snip]
> There are very strict limits on how much mains current is allowed and
> the types of capacitor that can be used. If the capacitor breaks down,
> the output will be connected directly to the mains, so two in series are
> often used to give a degree of redundancy. If one of the pair breaks
> down, that would give rise to excessive current, so tingling might be a
> warning sign that the redundancy has been compromised and something more
> serious is about to happen.
Similarly for switch-mode power supplies equipped with an earth
connection, but I think about 1mA earth leakage is allowed.
Some years back the company I worked for built a new office. The
electricity supply was several 30A ring mains, each with a 30mA earth
leakage breaker. In use each ring probably powered 30 computers -
sometimes many more. As a result the earth leakage breakers tripped
very frequently, even though the total load on each ring was measured at
well under 30A. I used a clamp meter to show the total earth current
was often above 30mA - so obviously the breakers would trip.
Over a weekend the installation electricians re-wired the distribution
board and split each ring into two spurs, each with a 15A breaker at
30mA leakage. Problem resolved.
--
Graham J
[snip]
> There are very strict limits on how much mains current is allowed and
> the types of capacitor that can be used. If the capacitor breaks down,
> the output will be connected directly to the mains, so two in series are
> often used to give a degree of redundancy. If one of the pair breaks
> down, that would give rise to excessive current, so tingling might be a
> warning sign that the redundancy has been compromised and something more
> serious is about to happen.
connection, but I think about 1mA earth leakage is allowed.
Some years back the company I worked for built a new office. The
electricity supply was several 30A ring mains, each with a 30mA earth
leakage breaker. In use each ring probably powered 30 computers -
sometimes many more. As a result the earth leakage breakers tripped
very frequently, even though the total load on each ring was measured at
well under 30A. I used a clamp meter to show the total earth current
was often above 30mA - so obviously the breakers would trip.
Over a weekend the installation electricians re-wired the distribution
board and split each ring into two spurs, each with a 15A breaker at
30mA leakage. Problem resolved.
--
Graham J
Yeechang Lee
Aug 22, 2021, 4:45:11 AM8/22/21
to
D.M. Procida wrote:
> If I use two fingers to scroll using the trackpad, when the machine is
> running from the battery power, it behaves as expected.
>
> When it's running from the charger, the scrolling is flickery and
> unstable, and also jumps from side to side.
As nospam said, your power is fluctuating. I saw the same thing when using my iPhone with the Lightning cable plugged into a USB port on a super-cheap charger with multiple ports; screen taps sometimes did not register. Replace the charger.
> If I use two fingers to scroll using the trackpad, when the machine is
> running from the battery power, it behaves as expected.
>
> When it's running from the charger, the scrolling is flickery and
> unstable, and also jumps from side to side.
--
geo:37.783333,-122.416667
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