View Full Version : crt testing


radio nut
11-18-2009, 10:47 PM
When I first started in radio and tv repair someone trained me how to use a tube tester. I was told not to trust tubes that test off the scale. As an ex. on a tv-7 if the tube should test 40 and it swings the needle over to 120 the tube should not be used. I am testing 10bp4 crt's as extra's for my motorola I am currently working on. On my B&K tester one tube tests 300 ,another 400, and the last tests 1,000. It is not shorted and the contrast test is OK. Any one see any problems with this?

Eric H
11-18-2009, 10:54 PM
Nope, sounds like you have two tubes that are fair to OK and one that's like new. :yes:

Are you using the usual B&K settings of G1 45 volts, G2 one small division above zero?

radio nut
11-19-2009, 10:30 PM
I would have to get the manual back out. If that is what it calls for then that is what I used. I do not like to guess. I have been burned before trying to figure out a setting on my own because it was not listed.

Eric H
11-19-2009, 11:20 PM
I have a B&K 466 and for that model that's the setting for most of the old B&W tubes I test, 10BP4 etc.
I'm not sure about other models of B&K.

radio nut
11-20-2009, 11:53 PM
Well, I guess it does not matter. I was showing a friend the tubes and tested all of them again, same results. They were curious and had me retest the strong one and this time it tested 200 and then slowly dropped to zero. Then to check my tester I retried the others and got the same results as I did the first time. The "strong" crt went dead in front of me.

radio nut
11-20-2009, 11:54 PM
I also tried resoldering the pins, it is still dead.