be (as) sound as a dollar

1. To be stable, sturdy, and reliable. That table must be as sound as a dollar to withstand the ceiling collapse with hardly a scratch. A: "I wouldn't stand on that rickety old stool if I were you." B: "Nonsense, this thing is solid oak—it's as sound as a dollar!" They're trying to convince me that this investment is as sound as a dollar, but I have my doubts.

2. To be in good condition. Once I sand this old chair, it will be sound as a dollar. The TV was acting up earlier, but it seems to be sound as a dollar ever since I smacked it. For such an old piece of equipment, it seems to be sound as a dollar.