Repairing a faulty DC-in board on an iBook G3

Discussion in 'Macintosh Computers' started by tk229, Apr 2, 2005.

  1. tk229 macrumors newbie

    Apr 2, 2005
    If you're having similar trouble with the DC-in board on your DC-in board, then here's how I managed to fix it:

    The Machine:
    Apple iBook 14" G3 800MHz MacOS X 10.2.8

    I'd been carrying my iBook around and when I got home and plugged it in, there was sharp crackle from the DC socket and the light on the plug did not light up. There was a smell of burnt electronic component or PCB (printed circuit board) coming from the socket. I unplugged it and turned the iBook on. It ran perfectly fine from the battery but it wasn't charging up. If I pulled the DC plug out a little bit, it tended to light up orange. According to the display, this wasn't charging the battery. I tried it with a different power supply but it was exactly the same.

    I took it to an Apple-approved technician and he said that he'd have to send it back to Apple and would cost a flat rate of GBP 300 (around $550). I might as well have bought a new iBook for that price so I decided to fix it myself -what's there to lose?

    First of all, back up everything whilst the battery lasts.

    Before you start, have a look at PBFixIt's excellent step-by-step guide on how to take an iBook apart. It's a little nerve-racking to take apart your beloved iBook so if you've not had much experience with electronics, you might want to give it a miss. This message is just a report of what I did so I can't take any responsibility if things don't work out.

    It's vital to take static caution because a small static (even unnoticed ones) can destroy electronic components. I used a static-sensitive mat and earthed wrist bands. You could just touch a metal appliance to discharge the static but it's better to be earthed all the time.

    Follow the steps in the guide. It's vital to have the right tools. You'll need a Torx screw driver for unscrewing the tamper-proof screws. You can get cheap ones for around GBP 5.00 ($9) for a set. PBFixIt also recommends a thing called a "Spudger". It's a thin piece of plastic you slide this into the slits of the case. It pushes the plastic hooks to unclip the case. It's only $6.95 so it's probably worth getting it but I just made my own from a slightly flexible plastic handle of a scalpel filed down so that the sharp edge can slide into the slits. It turned out to be a little too brittle for the job so kept snapping but eventually got the cover off with no cosmetic damage.

    You must keep track of all the screws and use the correct screws when you're putting the iBook back together again. If you use an over-long screw, you could pierce or short a PCB track. I had a compartmentalised pill box with each compartment numbered. I wrote down which screw went into which compartment at each step. You need to have a good system to keep track of the fixings.

    A few hours on and I eventually got to the DC-in board. It's buried right at the back of the system and possible the most awkward part to get to in an iBook. Really, the iBook isn't designed to be taken apart or repaired. The DC-in board is a tiny thing (around 1.5cm x 3cm) with a few components. I'm told that the power from the DC-in board goes into the Logic Board, where it controls the trickle of current that charges the battery. One technician even suggested that in the worst case, I may have to replace the Logic Board ($400 for the part).

    I unplugged the ribbon cable from the DC-board to the Logic Board and had a good look but couldn't see anything. Usually if there's a burning smell, it's a burnt out capacitor or an IC. A type of polar capacitors called tantalum capacitors are particularly dodgy and they pop in spectacular fashion so it's usually quite obvious. In this case, there seemed to be nothing wrong. A reconditioned DC-in Board from PBFixIt costs $80 dollars so I gave the old one a last go. I cleaned up the board so that there were no debris shorting out the tracks and also cleaned the contacts. I also checked the passive components for shorts with a multimeter.

    There has been concern about some faulty Taiwanese electrolytic capacitors. The story apparently involves industrial espionage and stolen recipes for the electrolyte:

    Whatever the truth of the story, it's something to be aware about. As far as I can tell, I think suspect components were manufactured over 2000 to 2002 or so when the story started to surface. Fortunately these chunky capacitors are not used in the iBook itself but worth checking the electrolytic capacitors if you come across problems with desktop motherboards and power supplies.

    So back to the iBook. I cleaned it all up and put it all back together. When I plugged the DC plug back in, the LED lit up and all was well. It's been four months and the iBook's been running fine. It's difficult to see what the cause was. Probably the contact of the ribbon cable to the Logic Board came loose or there were some debris shorting the tracks of the board (I'm not sure where the debrish could have come from).

    If you're experiencing similar problems, I hope this helps. If there is a problem with the DC-in board, you can buy reconditioned ones for around $70 from PBFixIt.

    Has anyone else had similar problems? Can anyone suggest what the cause may have been?

  2. diamond geezer macrumors regular

    Jan 26, 2004
    A brand new DC-in board for your machine costs only about NZ$15 (US$10) from Apple.

    Sounds like you're being ripped off.
  3. tk229 thread starter macrumors newbie

    Apr 2, 2005
    DC-in Board -how much?

    Well, actually if you read the detailed description, I didn't have to replace the DC-in board. After some cleaning and securing the connectors, it started working again.

    When I enquired about getting new parts from an Apple technician, I was told that new Apple parts were only available to approved Apple technicians so I wouldn't be able to get hold of them. I don't know whether that's true but if you know of where to get hold of new parts, perhaps you could let us all know?


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