substitute power jack for an iBook
Monday, February 5 2007
Opening up an iBook, doing something, and then closing it up again, is a complicated, delicate, and multi-step procedure that usually takes a number of hours. Yesterday, en route to replacing the power jack with something more robust and standard, I only got as far as taking the thing apart. An iBook is very delicate inside and with it open I have to work under the assumption that I may have already destroyed it irreversibly. Otherwise I'd be unprepared for the psychological blow that would inevitably result should I put it back together and it proved impossible to start up again.
The DC-in board (to which the power jack is attached) is a small circuit board, only about two inches long and a half inch wide. I had no intention of replacing this part (which costs about $60 if you can get it out). All I needed to do was to dig down to it (page 15 in the 20 instructional pages describing how to completely remove it). With the optical drive still fully in place, I was able to somehow swing the DC-in board out around that optical drive (though that board was still tied down on one end by a cable). Once I had the board up, I could access both of its sides to desolder and remove the flimsy non-standard power connector. I'd half-expected to see failed solders around its pins, but they were still fine. Evidently the narrow gold-plated contacts inside the connector had gradually become unreliable. (Towards the end there I'd had to be very careful to properly orient the power cord in that jack or the iBook wouldn't charge.)
I replaced the old jack with a standard RCA phono jack, the kind that can be mounted in a hole in a panel and secured with a lock nut. The hole in this case would be the old power jack hole in the iBook's case, which was a little too large, forcing me to use a washer that intruded slightly into the space through which the optical drive's hatch door passes. The thing about these ultra-small laptop designs is that they leave little room for the bulky, imprecise non-custom parts one normally has in one's junk drawers. But somehow I managed to cram that RCA jack into the old power jack hole and run wires down to two solder pads on the DC-in board. It turns out that, though the old power jack could discern between four separate lines, an iBook only really cares about ground and +24 volts. Those are all it needs to function on wall current and recharge the battery. (There's also a signal to make two different LEDs light up on the end of the iBook power cord, but, despite plenty of research, I've never been able to figure out what information is being conveyed by the green light or the orange light, so I can gladly do without that functionality.)
Once I'd attached an RCA plug to the end of the iBook's old power wire, the new RCA jack proved to be a very reliable power connector. All I really cared about was that the iBook was still working, so I left actually putting it back together for tomorrow. [In the end, once it was all back together, I came out with a surplus of two screws. I must not have been following the procedure as closely as I had when I installed the replacement hard drive two years ago.]
The old iBook power jack, removed from the DC-in board. Looking at the DC-in board and testing with a multimeter, I was easily able to determine which of its pins were for +24 volts, which was for ground, and which were probably for that glowy function that nobody actually needs.
The new RCA jack in my iBook (with a corresponding RCA plug soldered to the end of the iBook's power brick).
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