Mar 6, 2010

How to fix Lenovo R61i laptop AC power adapter

Just half an hour or so ago, my dad's laptop power adapter turned belly up. "This is gonna cost at least $50 bucks!" I said to my dad. Well it didn't. Fortunately, he remembered he stacked away a power adapter from our very first laptop. It had an output of 20 volts, like the damaged adapter and 6A max current, so about 120W. That's twice the old adapter's power. That shouldn't matter as long as the voltage is the same. It would only mean that it would run cooler because I'm sure the laptop has an internal current limiter so the battery is always charged within normal parameters.

I searched around the web for solutions to opening the power adapter as it had no screws and the only solution I found was hammering it with a rubber hammer to break the glue points, then forcing it open with just your hands. I didn't have such a hammer so I proceeded in another fashion. I stuck a flat screwdriver perpendicular on the line that glues the two plastic case parts together. Then I proceeded to hammer gently on the back of the screwdriver, being careful not to go through the plastic, only to undo the glue points. Then I moved the screwdriver one unit of its width further and did the same thing. Eventually it opened cleanly. Patience helped. :)

The rest was just solder work and making sure wires don't short circuit. I decided to move the cable from the old adapter to the new one so I had to do some cutting as the rubber "gaskets" that held the wires onto the case, were of different shapes. If you do this, be sure to cut it so that you don't reach the metal wires themselves and so that you leave a small canal so the gasket doesn't come out when the wire is pulled.
I also did a little trick. The wires weren't long enough so I had to solder the positive (+) wire onto the wire of a short-circuit protection diode that landed in the same spot on the printed circuit board as the actual wire solder point. I also made sure to isolate the diode so that it doesn't get pulled and touch nearby elements.

Now it seems it's working perfectly. 54 minutes till fully charged.
My dad promised me a beer too. :D

Here are some pics: