[kbmuri]

Yeah, I recapped and re-tubed the Heathkit Cap Checker (pictured above), so I guess my ten-dollar price jumps to 30 or 35. After that, it calibrated easily and is a valuable work horse.

My Sencore tube testers each have one 12AZ7 tube under the covers. Both are 40+ years old and both still have the original tube and each checks the other tube as NOS. So whatever the tube tester uses it for, it's apparently not a heavy load. And I suppose the tester isn't on continuously like a TV or radio, so the hours on each 12AZ7 is probably still pretty low. If the 12AZ7 went bad in either, I'd just pop another one in and go. What will you do when your solid-state IC craps out?

I agree a person should put in all new caps, but for one, you're not guaranteed the new cap you just bought hasn't been sitting on a shelf in the sun for two years, or wasn't a "return" part, or wasn't just a factory defective. Small insurance to test each cap before putting it in.

If you're troubleshooting, it sometimes pays to leave in caps that test good, and focus on the ones that test bad, until you've got a working set (TV, Radio or Audio), and then decide if you want to recap the entire thing.

The main power-filter caps are, indeed like a airline pilot, they take others down with them. But the smaller paper caps, even the micas and ceramics, can also go bad (although rarely). The Heathkit above tests them all. Definitely worth the price of admission.