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Day: December 6, 2008

iMac G5: Worse Than Before

Image of the machine in Open Firmware showing video glitches present after recapping. I suspect that there are cold solder joints and the video card isn't getting proper power.

Well, I managed to get all the capacitors I previously complained about desoldered and the new parts fitted. However, the iMac G5 now displays video glitches while POSTing, and it never boots past a plain blue screen with an artifacted cursor. As can be seen above, video glitches are also present in Open Firmware.

Looking at this photo (large size here) and seeing what may be some cold solder joints I suspect that some of the caps — specifically those for the video controller / memory — aren’t doing what they are supposed to. This means that I’m going to be taking the machine back apart tonight or tomorrow and attempting to reflow those joints.

I’m disappointed. It really frustrates me when I screw something up.

UPDATE: I think I should probably take a look at the display cable and its connector as well.

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I Fail At Desoldering

Another view of the domed caps, after some of the dried electrolite had fallen off.

My grandparents computer is an older iMac G5. When installing an Airport card in it last weekend I noticed that a number of the capacitors were domed, and some were leaking electrolyte, a sure sign of failing capacitors, possibly because of the capacitor plague. After digging around through Digi-Key, Mouser, et al I found that the cheapest way to get a set of replacement caps is to order them from The Cap King. He sells a set of the 25 needed caps for $16 shipped, and the set arrived earlier this week.

After sorting the caps, tearing down the iMac, and removing the logic board I identified which caps needed to be replaced, marked them by type, then set about desoldering two of the most accessible ones. This is where I began to have problems.

Normally I’m pretty decent at soldering, but getting these first two caps out was difficult. The first one left a lead sitting in the board, and the other three holes still contain solder. I presume its because of the number of layers in the board and the giant planes of copper near them, but I cannot seem to get enough heat on the board to melt the solder all the way through and wick it out.

Here are two photos of where things currently stand: 1 · 2. I think the next thing I’ll try is pre-heating the board with a hair dryer, then leaving the hot air flowing over it while attempting the desoldering. Hopefully that’ll help.

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