07-22-2019 04:21 AM
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07-22-2019 08:27 AM
Symptoms point to 3 different problems, which seems unlikely. Not turning on with battery installed points to a short circuit in the battery, but power plug only working in one orientation points to a broken port. Turning on immediately points to dead CMOS or a short in the power button. I could do a better job of diagnosing if I could see it, but you and I are a long way from each other,
07-22-2019 02:35 PM
Hi and thank you very much for your response.
The external battery is fine, it works on a different T440s and the working eternal battery from the other T440s won't work on the faulty on.
By CMOS do you mean the CR2032 battery? It was working when the laptop failed and since then I've removed it (but haven't replaced it yet, but the laptop starts under the conditions outlined above).
Do you know if the power button component is 'modular'? In that, could i find and install a replacement or is it integrated into the motherboard? But would a new power button resolve why it won't start on battery?
07-22-2019 03:59 PM
The CMOS battery is the little yellow disk that plugs into the motherboard. If that is missing, it will start as soon as it is plugged in. It should start with a working external battery, unless the internal one is shorted. If the CMOS battery is missing, I'm not sure what will happen if there is no A/.C connected. The power button is part of the palmrest, but there is a little modular switch that screws in from the bottom. It can be replaced separately. It can be tricky to get into the correct position, especially if you haven't done it before.
07-22-2019 04:40 PM
Thanks again for the insights.
Would a new power button solve the problem of not starting with either battery attached? Or the polarity of the plug? Or would they be separate issues?
07-22-2019 05:23 PM - edited 07-22-2019 05:24 PM
The plug has no polarity. There are 3 connectors. The outside face is ground. The inside face is +20v and the center pin is connected o ground through a resistor. The resistance indicates the capacity of the adapter. I think your problem is more than the power button, but again, I would need to see the machine to be sure
07-26-2019 09:28 PM - edited 07-26-2019 09:30 PM
Hi, thanks for your insights so far. By replacing the CMOS battery the laptop turns on as normal - plug in either orientation and not until the button is pressed.
However, it doesn't turn on without the cable being plugged in (i.e. cannot turn on from battery).
Once on, both batteries are recognised and have charge and I know that the external one works because I've tried it on another laptop. However, if I remove the plug while on the laptop turns off immediately - no power seems to be available from the batteries.
Any ideas why the laptop can't draw power from the batteries but can see them and see how much charge they have?
07-31-2019 03:13 AM
For anyone that encounters the same problem, there's a blue cable inside the T440s that runs from the power switch to a metal sheet towards the left half of the laptop (and towards the back from where the drive sits). This is held down with a small piece of clear tape. Mine had come unstuck. By replacing the tape so that the end of the wire makes contact with the metal sheet the laptop starts from battery as normal.
So, my T440s works as normal after:
(1) taping the blue wire back down with a new puece of tape
(2) replacing the CMOS battery.