Before I attack anything particularly valuable, it seems like a good idea to learn how to desolder multi-pin ICs without destroying everything around them. I’ve got an old RAM board for practice and a heat gun, so let’s see how much trouble I can get myself into.

The first experiment involves removing small memory chips from the board. With the heat gun set to around 320°C, the solder begins to soften and the chips can be lifted away. I’ve also got a little vacuum pickup tool, although it doesn’t seem particularly interested in cooperating.

At one point an entire section of the RAM board comes loose instead of the chip I was trying to remove. That’s probably a fairly good indication that I need some more practice! To make things even better, the heat gun eventually stops producing hot air and displays an error. Apparently it’s had enough for one afternoon.

After switching the heat gun off, unplugging it and letting it cool, I managed to get it working again. This time I tried a few more memory chips, experimenting with lifting them carefully once the solder had softened.

The results were considerably better. Several chips came away with their legs intact, and I managed to clear one whole side of the memory board. I’m starting to get the hang of this!

Of course, the real reason for all this practice is that I want to remove a QFP processor from the Amstrad Mega PC and attempt a replacement. That’s a considerably more difficult proposition than these small two-sided memory packages, so I thought I’d better develop at least some idea of what I’m doing first.

The third video looks at cleaning the solder pads after removing the chips. I’ve been experimenting with desoldering braid to absorb the remaining solder and leave the pads ready for another component.

It’s rather satisfying seeing the cleaned pads beside the ones I haven’t touched yet. The difference is obvious, even if my camera is determined to make focusing on the tiny connections as difficult as possible.

I was still using the heat gun for some of this work, although a soldering iron is much more appropriate for cleaning individual pads with braid. Proper hot-air rework equipment would also give better control over the heat applied to a valuable multilayer board. These are practice experiments on scrap hardware, not necessarily techniques I’d recommend copying.

Desoldering success! Now I just need to learn how to solder the chips back on again. That should be interesting. Assuming I can find the energy to wake up before the afternoon, of course!

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