HP 21 not powering on - repair/troubleshooting advice

[[kby]]

Don’t worry too much about the dilution—what’s needed will depend on how bad the corrosion is. The dilution doesn’t make the acid able to attack things it wouldn’t be able to attack as a dilute solution—for the most part—it just allows it to digest a larger quantity of material. It is more important to get it all off before powering on. I usually use full strength household vinegar (5%; not the 30% stuff more because of safety than because it word destroy something). I usually go only an hour although I have sonicated it as well to speed things up. I then rinse a couple of times with RO water and then isopropanol, finishing with a hair dryer (not too hot). Before you soak, try to notice places that look like they might disappear completely if the corrosion is gone as they may need to be rebuilt after the wash. Make sure under the chips gets dry, too.