7jp4 testing

[Kevin Kuehn]

I hear they can test strong on the CR 70 and still have a dim picture - something about the phosphor getting weak, I think. So ultimately you'll need to plug one into a working TV to get the whole picture.

[pendulum]

Yeah, the cr70 really is just good for seeing if the tube is holding vacuum, if it is shorted, and fixing shorts. They almost always test very good. Really the only true test is putting it in a working tv.

[bandersen]

Yes, they do use different voltages than magnetically deflected CRTs. The CR70 has a mode switch specifically for electrostatic 'scope' CRTs. You'd need to compare the datasheet for a 7JP4 to something like a 10BP4 to figure out the exact differences.

Originally Posted by pendulum

Yeah, the cr70 really is just good for seeing if the tube is holding vacuum, if it is shorted, and fixing shorts. They almost always test very good. Really the only true test is putting it in a working tv.

I agree. I've tested 20 or so 7JP4s and all had very good emissions on the CR70, but definitely vary in brightness when actually used.