I would suggest checking the PSU (by substitution) before attacking the
computer and maybe causing more problems.
It's quite possible the output is low in voltage or has AC ripple on it.
This often makes it possible to run the computer OR charge the battery, but
not both.
To test the PSU you could measure its output with a voltmeter and a suitable
load, but this won't indicate ripple, for which you'd need an oscilloscope.
Thus a substitution-test might be easier.
Most Acers use a 19v 3.75A centre-positive supply, and this is a fairly
common arrangement. One or two models use a special plug, but most are the
easily-available 2.5mm ROCA type. Just make sure that any replacement is of
the right polarity and that it cannot be accidentally reversed - which could
seriously damage the laptop.
>> Stay informed about: Power problem with Acer TravelMate 2700 notebook