Question Laptop powers on with battery but not AC

Jan 24, 2020
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So I have a bit of a reverse problem than the majority of the threads I've found around.

My father found an old Acer Travelmate 5720 in the dumpster. The thing was looking fine, but there was no AC adapter with it. We turned it on, it booted and worked fine, battery is still roughly 60% full. We tried giving it some AC power with an exact spec AC adapter from another laptop of roughly the same age and despite the plug being slightly loose, we had it work ok. So far so good.

Now, the problem: this morning my father tried another AC adapter, didn't really check the plug, and when he inserted it, he got a small spark on the outside of the port. Since then, the AC power doesn't work anymore (not even with the AC adapter that had previously worked). The computer still powers on, boots and can be used to do stuff on the battery, but the battery itself doesn't charge anymore and of course on AC power only it doesn't turn on at all.

In the afternoon I disassembled it but I didn't spot any burnt stuff (neither did it smell). Anyone got tips on what to test or look for? If it was deep fried it wouldn't work on battery either, I guess, so I'm at a loss.

I know this laptop is ancient but it is in otherwise pristine conditions and I could actually use it to run some old software, so I hope it can be mended somehow.
 
Sounds like you got lucky and didn't damage the motherboard, but the charger port is likely damaged. You don't have to see it for it to be damaged.

If you have the right tools (and feel capable) you can check to see if power from a working charger is getting into the laptop, but to be honest I don't think it is.

Also, the charger you and he tried (if different ones) while they could be comparable to the original doesn't mean they are the right one for the device. Using the wrong charger can create a host of problems.

In the end, and if it is worth the cost, you are likely going to have to replace the port and get the right charger.