5" B&W Service Technician CRT Question

[Chris K]

I forget the tube number but I'm sure you'll know what I'm talking about...the small 5" RCA CRT techs would use instead of the full size one in the set to make it more maneuverable and less cumbersome. So far, I've used mine on 2 chassis as substitute CRTs, both housing 10BP4s. The resultant images have been...well...meh. Are they useable as a substitute for any other type of B&W CRT? The more important question...I understand they are electrostatic and don't need an ion trap but what about the other 2 components usually found around a 10BP4...the focus coil and the yoke? Can it be used as a stand alone on the bench? In other words, can I lay it on my bench with the HV anode and socket attached and get a picture I can work with or does it need to be in a yoke/focus coil (electromagnetic on these sets) assembly to get the image right?

I guess I could go home and try it but I've fried a number of things I thought would be in no danger before if I did what I wanted to do!

Thanks all
Chris

[dieseljeep]

Originally Posted by Chris K

I forget the tube number but I'm sure you'll know what I'm talking about...the small 5" RCA CRT techs would use instead of the full size one in the set to make it more maneuverable and less cumbersome. So far, I've used mine on 2 chassis as substitute CRTs, both housing 10BP4s. The resultant images have been...well...meh. Are they useable as a substitute for any other type of B&W CRT? The more important question...I understand they are electrostatic and don't need an ion trap but what about the other 2 components usually found around a 10BP4...the focus coil and the yoke? Can it be used as a stand alone on the bench? In other words, can I lay it on my bench with the HV anode and socket attached and get a picture I can work with or does it need to be in a yoke/focus coil (electromagnetic on these sets) assembly to get the image right?

I guess I could go home and try it but I've fried a number of things I thought would be in no danger before if I did what I wanted to do!

Thanks all
Chris

You have to use the yoke to get a picture! When I did TV repair, I used to leave the CRT in the cabinet, like RCA's and a few others. The small sets like Admirals and others that the CRT was mounted on the chassis, I just used the CRT that came with the set, unless there was a question about the CRT. Then, I would remove the CRT and try the test tube, leaving the focus unit and ion trap aside. My CRT was a 8XP4.

[bandersen]

5AXP4. Only focus is electrostatic. You have to use the yoke. It's magnetically deflected.
Ideally, you will remove the focus coil. It interferes with the self focusing gun. Image should be outstanding and sharp.

[Electronic M]

You can technically use the 5AXP4 or 8AXP4 in any TV set from 5" projection CRT up to ~27-30" direct view that uses the same CRT socket....With several caveats.
Heater has to be 6.3V parallel heater or a series heater with the same mA current rating as the test tube (or you have to rig your own heater load/supply).
The 5" test tube is meant for the early narrow deflection/deep tubes and the 8" is meant for the wide angle shallow tubes...You can use them in the opposite sets with the caveat that the 8" will be underscanned to look like the 5", and the 5" will be overscanned.

Both test tubes will work in a magnetically focused set but if you use the focus coil/magnet on the test tube it'll ruin the focus.

They made test kits with universal yokes and extension cables for the HV and socket for all test CRTs...on magnetic focus sets with a yoke plug it's often easier to use the test jig if you have it (I have one).

[bandersen]

Right you are. More specifically.

5AXP4 = 54 degrees
8XP4 = 90 degrees
8YP4 = 110 degrees

[Chris K]

I took the focus coil off my GE Locomotive and the 5AXP4 has a clear, crisp image...of the raster. Now, I need to get the video and sound back! It was working before but something happened. Need to look at the antenna connections then I'll test tubes. If the problem isn't there, I don't relish what comes next.