MacFormat UK – September 2019

Mac hardware GENIUS TIPS

Can a T2 Mac

be used in

Thunderbolt

Target mode?

> Provided it runs

normally, you should

be able to do this by

starting up with the

T key held down.

To mount its internal

storage on the

controlling Mac, enter

the FileVault password;

without that you won't

be able to get past its

built-in encryption.

Do internal SSDs

have thermal

throttling?

> No, as they have the

full power of the Mac’s

cooling systems to chill

them. Those include

fans and air ducting, and

if needed the processor

is slowed to maintain

suitable temperatures.

Hardware

quick-fire

questions

SEPTEMBER 2019 | MACFORMAT | 59

Open System Information and select the

Power item in the Hardware section. That

should display the full charge capacity of the

battery. For a 13-inch model, that should

equate to 63.5Wh, a 15-inch 77.5Wh, and a

17-inch 95Wh. Contact the supplier and check

which battery they supplied, and whether it

was correct for your specific model.

If, for example, your Mac needs a 77.5Wh

(7600mAh) battery, and they supplied a

63.5Wh (6600mAh) unit, the battery will

discharge rapidly when the mains cable is

unplugged. Replace it with the correct battery.

Q

I replaced my MacBook Pro Early

2011 battery through a reputable

supplier, but now it discharges

rapidly and needs replacement. I’ve tried

resetting the SMC, and hardware diagnostics

are fine. Do I need to replace my Mac?

by MICHAEL O’KANE

A

Like all replacement components,

some turn out to be defective, even

when you’ve paid for a reputable

branded or Apple-labelled battery. The

commonest cause is the wrong capacity unit.

Q

When I tried to turn my

MacBook Pro on, it wouldn’t

respond, so I put it on charge

for half an hour. When I tried to start

it up, it showed a screen full of filled

circles, and eventually asked for my

password. I shut it down, and five

minutes later it worked fine again.

What did I do wrong?

by COLIN HEATON

A

Any laptop Mac which is

reluctant to start up should

be left on mains power for half

an hour or so before trying again, just

in case its battery needs that boost.

Display problems may then reflect

that your MacBook Pro's SMC needs

resetting, or it could be an early

indication that its graphics card is

starting to fail. It’s worth resetting your

MacBook's SMC and NVRAM if you do

encounter them; SMC problems could

also account for your initial difficulty

getting it to start up.

For recent MacBook Pros without

a T2 chip, this is easy to do. With the

MacBook Pro shut down and connected

to mains power, hold the left ß, ≈

and å keys while pressing the power

button for 10 seconds (as detailed in bit.

ly/mfrsmc). It’s more tricky when your

Mac has a T2 chip, though.

If that doesn’t resolve the display

mess, start up with the D key held to

enter Diagnostics and run those tests.

Display mess on start up

New battery discharges quickly

At the first sign of battery issues, open

the Power item in System Information,

where you’ll find further details.

macformat.com @macformat

If potential hardware problems aren’t fixed

by resetting the SMC and NVRAM, start up in

Diagnostics mode and run hardware checks.