I couldn't resist snatching up a non-booting 660av on eBay for $25. The battery hadn't leaked, so I figured it probably just needed a recapping. It was sold as non-booting, but the seller could hear the hard drive spin up.
When it arrived I powered it on. I actually got video output, but it was garbled and the hard drive had trouble spinning up and booting. I don't care about the hard drive since I can replace it with a SCSI2SD. The video output had me a little concerned though. I started looking around on the board.
I didn't pay close enough attention to the picture in the auction. It looks like it's been exposed to moisture of some kind. There was rust on the CD drive. The worst part was the legs of the CIVIC (Cyclone Integrated Video Interfaces Controller). This is an Apple ASIC that appears to act as the intermediary between the VRAM and everything else from what I can tell in the 660av/840av devnote. You can see the green on the legs in the picture below (the wetness on the bottom of the chip is some flux I put on to try to reflow the solder):
I guess it was partly good news and partly bad news. The good news was that the video was screwed up and I had a pretty good guess for what was causing it. The bad news was that it was corrosion.
I used hot air to remove the chip. First I covered the surrounding part of the PCB with Kapton tape and then covered that tape with aluminum foil tape. The whole idea was to protect the surrounding components. I've been told that putting Kapton tape down first makes it easier to remove the aluminum tape. After trying it, I would definitely have to agree with that. Then I used a thermocouple to measure the temperature and went around and around and around the chip with the hot air nozzle. When it got hot enough I was able to lift the chip off, and here's what the pads looked like:
This was good news; none of the pads were gone. A lot of these pads really did not want to take any solder, so I had to do some cleaning. I used a pencil eraser which worked pretty well. After the eraser and solder wick, it looked more like this. Still not perfect, but much better (some of the weird bits you see in the middle are pieces of pencil eraser I cleaned off later):
As you can see, some of the vias still have some damage and the corrosion has probably already gone into them. There's not much I can do about it. For $25 I won't be too upset if it eventually fails.
That completed the pads, but the chip was pretty bad too. I tried lots of things on the chip legs. I did the pencil eraser as best as I could, I tried red DeoxIT, and I tried scraping corrosion off with an X-Acto knife. I thought I had the bottoms of the legs looking pretty good so I put some solder paste onto the board and put the chip back on. Unfortunately something still wasn't right and I could only make it work if I pressed down on the chip. The display also had vertical stripes if I went into thousands of colors mode.
Finally, I got some fine-grit sandpaper (400, 600, 1000) based on advice from balrog. It's pretty tough to use sandpaper on small IC legs, but I think it may have helped clean some of the corrosion off. I did a little bit of sanding with the chip soldered down because it felt less risky that way. I removed the chip with hot air again and did some more careful sanding on the legs. I finally began flooding the legs with flux and solder until I felt like the legs looked clean and were taking solder well. I ended up cleaning off a lot of gunk, although I think a lot of it was just flux residue.
With cleaner-looking legs I felt more comfortable doing drag soldering. I did have a few hiccups where a few of the legs didn't solder down at first and I ended up with chimes of death, but I was able to find and fix them. I also lifted a pad while trying to separate two legs that I accidentally soldered together (oops!), but the pad is still attached to its trace and it's a nice thick power trace. I'm not too worried.
It looks a lot better now. Not perfect, but way, way better:
Last night it wasn't booting at all, which I'm almost thinking I should blame on the capacitors because the startup chime was all garbled (when it even played). This morning I did some cleaning with isopropyl alcohol around the CIVIC and the caps, and now everything is working great. I will definitely replace the caps, stick a SCSI2SD in there, and call it good.
Here is a "selfie" that the 660av took of itself through a camcorder hooked up to its composite input jack.
I burned myself with hot solder wick twice last night and then cut my hand on the case. I was almost about to go "Office Space" on this computer, but I'm glad it finally seems to be happy now.