I'm working on restoring an RCA 730TV1 and have the problem you see in the picture below.
http://farm8.staticflickr.com/7165/6501299713_4d600b5605.jpg
I'm pretty sure it's an ion trap not quite in the right place. This set has two traps on it, one that is wired to the set (electromagnet?), and I can't seem to get a full raster. Any one have an idea that I might be missing?

The position of the focus coil also affects the raster position. Try moving it around, along with the ion traps.

The position of the focus coil also affects the raster position. Try moving it around, along with the ion traps.

I just ran into that. Focus coil was off centered to the crt neck.

Do you mean it's a double pole trap, wired to the set with one large coil and one small?

It does look like the Focus coil might be off, that also controls centering.
The trap is in the right place where it makes the raster brightest, the Focus coil is adjusted after the Ion Trap.

There is some interaction between the Ion trap and the Focus Coil so you may have to go back and forth.
Also make sure the Yoke is slid tight up against the bell of the tube, not just the rubber bumpers but the Yoke itself, if you loosen the wingnut you can slide it forward.

If the Ion Trap or the Focus Coil is on backwards (front to back) it will cause problems also, the small coil or magnet on the Ion Trap goes to the front of the set.

I just ran into that. Focus coil was off centered to the crt neck.

Centered isn't always the best position. Sometimes you have to intentionally adjust it to a position significantly off center and out of plane. Just do whatever gets you a nice centered picture with no shadows.

As mentioned above, there can be significant interaction between the ion trap and focus magnet. It may take a while, but you'll likely find positions for both which give you a nice bright, centered picture with no shadows.

There should be a small permanent magnet on the neck of the CRT. Move that around for the brightest pic.
See banderen's video on how to adjust this: http://www.youtube.com/watch?v=G53ZNOsAYRw&list=UUJ6nWQ7UO-Lve9ji2FUNYwg&index=2&feature=plpp_video

There should be a small permanent magnet on the neck of the CRT. Move that around for the brightest pic.
See banderen's video on how to adjust this...[/url]

The really early RCA sets used electromagnets rather than permanent magnets. It serves the same purpose though.

This set has two traps on it, one that is wired to the set (electromagnet?), and I can't seem to get a full raster. Any one have an idea that I might be missing?

I've never heard of a set using both the electromagnetic and permanent-magnet ion traps. My 721TS and 8T244 just use the permanent magnet, my 630TS just the electromagnetic one. Maybe try using just one or the other?

There is both an electromagnetic and permanent-magnet ion trap on this set. I've tried to read as many posts as I could about this set before I started and in almost every one I read there were several people that were surprised that they were both in place. The focus coil was at fault for the shadow. adjusting it's position made the shadow disappear. I will do some adjustment tonight to get the bell of the CRT right up to the coil, then adjust the ion traps to make the raster the absolute brightest, then on to the focus coil for no shadows.

I would hazard a guess that someone added the extra trap because the electromagnetic one failed at some point.

Have you tried it without the extra PM trap?

If it works without the extra trap then leave it off, if it doesn't then there's a problem with the Electromagnet trap that needs to be resolved. I seem to recall it' gets it's voltage through one of the large wirewound resistors inside the Black heat sink on the back, if it's open it won't work.

You can use just a PM trap of course but it has to be a double type trap, this is about twice a thick as the single and will have a large end and a small end same as the EM trap.

I would hazard a guess that someone added the extra trap because the electromagnetic one failed at some point.

Have you tried it without the extra PM trap?


:) that's what every one else thought on the last thread about this model.
http://www.antiqueradios.com/forums/viewtopic.php?f=3&t=136261&start=80
look about 1/3 of the way down the page to Steve's picture of the PM trap. His set up is identical to mine.