Classic Hifi Care

Hello guys. Purchased a new to me tube tester B&K dyna jet 707 . Been having fun doing the testing. one of the problems with buying stuff like this is you may have to refurbish it before you can use it. I purchased this one because the guy said he had gone through it completely and did a transistor replacement of the "problem tube" these units have. Only found one bad tube in the stereo's but only about half done. I noticed on one of the tubes that it reads bad but I then tested several of the same ones and they have the exact same reading so I think my book settings is wrong.?. Still its been fun. Here is a photo

With all of those sockets it looks like it would test every tube known to mankind. Nice find!

Bill

And bear in mind that some tubes that test badly will work just fine in-circuit. I usually look mostly for shorts and leakage.

Chris Campbell

Hello Chris, what do you mean by leakage ?

I have a 707. The "problem tube" with them is a 12AX7. I don't like the way this tester tests for shorts, otherwise, I like it. Output tubes should be professionally matched for best performance, particularly in a Magnavox bi-amp.

Hydrolastic wrote: ↑Sun May 17, 2026 8:05 pm Hello Chris, what do you mean by leakage ?

The straight answer is "I dunno." It's a test on my testers. I always assumed it was a gassy tube.

My testers are emissions testers, not transconductance devices, so unless the quality (total emissions) is down at ankle level, I assume a tube is good enough if it has a functioning filament/heater and no shorts.

Chris Campbell

ok looked up the unit here is what he said.... "The important solid state rectifier modification was done making the tester much more consistent and eliminating the need for that big #83 rectifier tube that keeps the unit hot all the time."