Keiron said:
Thanks all for your previous answers but I thought I'd start this new
thread instead of carrying on the previous one as I wrote the earlier
description of the fault from memory and having just replicated the error
again here is a better description from which you might be able to work:
So, using the laptop ... dumdeedum.... for an hour this time. Then laptop
completely powers down, not even any flashing LEDs to indicate power
coming in from the AC (battery not in at time of use so irrelevant).
However the indicator LED on the power supply is still on. The laptop
will not power on now until it has 'rested' a while, presumably until it
or the power supply cools. It will then work as normal, until the error
occurs again. What does this indicate? Remember no lit LEDs on laptop and
power supply LED on the actual brick is still lit.
Now, I know this seems like a laptop issue rather than the PSU but there
is no obvious issue with the laptop other than this and the PSU on the
other hand does get very hot so it may well be a the cooling of the PSU
which is the factor. Not using the machine for particularly instensive
tasks when this happens- web browsing and playing an mp3 maybe. Probably
30/40% cpu usage.
Any further insights?
Thanks
"the PSU on the other hand does get very hot"
There's your clue. If the new adapter is getting very hot and
shutting down after an hour, it could be the adapter is protecting
itself.
Now, you need to find out, exactly how much power the laptop is using.
It could be, the laptop is using excessive power. Consider for a moment,
the history of your computer. At one time, it had the "original" adapter.
Did the original adapter die, because of a frayed cord or broken
connector ? Or did it in fact die, because it overheated like the
replacement you're using now ? That would tell you the laptop
is the root cause of your problem.
You need some way, to measure the current flow, to see whether everything
is operating the way it should.
Will the laptop operate without the battery present, and the adapter
plugged in ? If so, then you would know it isn't the battery charging
circuit which is causing the overheat on the adapter.
Perhaps the power adapter is being asked to charge the battery, and
run the computer, at the same time, and the combined load is too much.
That implies the battery charging attempt is drawing more current
than is normal for the charging circuit.
If I was going to measure the current flow from the adapter, I'd use
my clamp-on DC ammeter. I would need a male to female, barrel connector
equipped adapter cable, because my clamp-on ammeter can only work,
if one conductor can be encased in the jaws. (I could split the wires
with a hobby knife, but that is making a mess of the cable. Most
people wouldn't like that.)
You can see in this sample photo, the user has an adapter cable, with the
two wires split, such that the jaws of the ammeter fit around just one
wire. The ammeter detects current flow, via the magnetic field associated
with it. I have a meter like that, which can measure both DC and AC
currents (internal Hall probe detector), and that is how I check current flow.
http://2manytoyz.com/hurricane/0415.jpg
(Mine looks like this model, but is made by another company - approx $300 or so.
It costs a lot more than a hardware store multimeter would.)
http://www.powerstream.com/z/cm-11.jpg
When you buy an adapter, it has a power rating. Say the adapter was
65W and supplied 19V. Dividing 65W by 19V, gives the max current
in amps. That would be about 3.4 amps. I would take your laptop, in
its about-to-overheat state, measure the current and compare the
value to 3.4 amps. If higher than 3.4 amps, we know the laptop
is the problem. If lower than 3.4 amps, and still shutting down,
the adapter is substandard, and not living up to its spec.
You need to find someone with an ammeter, and an adapter cable,
to make the measurement. You can make your own adapter cable.
You can even use a conventional multimeter, on the amps range,
since in the process of making an adapter cable, you might as
well wire in the multimeter. The advantage of a clamp-on
ammeter, is you don't need to wire it into the circuit. The
clamp-on ammeter is a "non-contact" measurement device.
+---------+
| |----------------------------> Laptop
| Adapter | 2 wire
| |---------+ +--------> Input
+---------+ | |
+-------------+
| Multimeter |
| 10 amps max |
| Scale |
+-------------+
Switch mode power supplies, inside wall adapters, cannot afford to get
hot. With a plastic casing, there is no where for heat to be dissipated.
Thus, the adapter must be very efficient, so there won't be a lot of
waste heat. That being said, the power rating of the adapter,
does give you some idea of its limits, and if you're connecting a
65W adapter to a 95W laptop, then again, you'd have a problem on
your hands because of the "mismatch of expectations".
My guess is, your problem is related to charging the battery.
That's all I can suggest at the moment.
Paul
