Laptop Power Supplies or "PSU"
supplies unit are truly global, you can use your notebook in any county because of
Where to begin? Well the PSU is inside the computer, the
power adapter is connected from the AC to the computer. Fooled you.
You thought the little black box that had the AC cord was
For those that know go on down the page. It works like this: Because a laptop
is considered a device that is 'Global' the first manufactures needed to come up
with a way to get 110 to 240 volt AC to the laptop.
Solution: create a device that only reduces the AC to 20 - 12 volts DC with
an amperage high enough to drive the PSU inside the notebook where it
converts the voltage to DC with the +5, -5, +12, -12, +3 and -3 volts that the
components of the computer need to operate. Cool huh? Those guys thought it out
and now if you travel to some far off place and they have Electricity you can
use your laptop and charge the battery for those places that don't!
Note: Do not take these voltages/amperages as gospel, check you own system to
find out what can and CAN NOT be
The components that supply electrical power to the notebook has three
- AC adapter
- Power Supply
So now you know that you have a device that will reduce voltage and amperage
to a safe level for your laptop.
Some things to know about laptop power supplies:
1) They will fail with time. Nothing lasts for ever, even stars burn out.
2) On battery the power supply will not
produce enough power for some external USB devices, sorry the battery can only
supply so much.
3) My experience is that the power adapter will fail long before the power
supply, may want to get a spare and store it. When the original fails there may
not be any left to buy.
4) When a battery will not charge anymore it is 99% the battery and not the
power supply. If you have two batteries and neither will charge then it is your
power supply in the computer.
5) When the computer starts to age the battery does too, it will not hold a
charge as long as it did when it was new, see my battery page for more info.
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6) Your power supply is a marvel of engineering, it either works or it
doesn't and when it fails replace it.
Your power supply trickle charges the battery, if the battery gets hot
while it charges but will not hold a charge remove the battery from the laptop
and get a new one. Leaving a bad battery in the laptop will damage the power
Notebook power supply repairs:
As with any power supply there are no usable parts in the device, and fixing
the power supply should only be done by a qualified electrical technician only!
Now replacing a power supply in a laptop
can be a easy task or a nightmare, it depends on the computer. I have changed
out a Compaq power supply in less than an hour, then again the last Toshiba I
power supply I changed took me half a day.
Depends on the manufacturer. You will
have to at a minimum open the
case, remove the
keyboard, some you have to take the motherboard out of the case to get the power
supply out (Toshiba).
Always check the computer manufacture for availability of a replacement and
documentation on replacing the laptop power supplies.
Over the last couple of years there have been questions in the (now gone)
Q and A about fixing the internal power cord adapter (or jack), some are
mounted in a plastic frame, some are soldered to the power supply pcb.
The plastic frame or mount can be glued but you will have to experiment with
what type of glue you can use on your laptop case. The cases are made out of
impact resistant plastic and I know for a fact that "Acrylic Super Glue" will
Those that have the adapter soldered to the power supply pcb you can
re-solder that joint, see this
page on a small tutorial on soldering.