Quote:
Originally Posted by Chris K
I attached the page of the schematic that shows the ion trap as electromagnetic...just so you can take a look and confirm.
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Not enough resolution in that schematic to read, but RCA and others did use electromagnetic ion traps for the first couple of years after the war.
If there's wires going to the ion trap and you're not mistaking it for the focus coil or yoke, then it's electromagnetic. Some chassis switched to permanent magnet ion traps mid production and those sets will show an electromagnet trap on the schematic but not have one*.
Regardless of whether a trap is electro or permanent magnet it needs to be positioned correctly. Standard adjustment procedure is, with the set running, to spin the trap 360 on the neck while moving it fore and aft and watch (in a mirror if necessary) the screen for light as you do so. It's not uncommon for a permanent magnet trap to be on backwards, sometimes you need to remove it and flip it so that the ring opening that faced the screen faces away from the screen.
The electromagnetic ones often have an intensity adjustment on top of the mechanical positioning to worry about. I wish I had more experience with electromagnetic traps, but my Philco 48-1000 and RCA 8TS30 (630 chassis) are both later production PM trap sets.
*Schematics are rarely gospel on how a set is actually wired. Most schematics only capture one revision, or production run of many, and production and revision changes aren't always documented, or if documented often are hard to find documentation for. Also Sam's photofacts while great for readability and standardization of drawings are prone to typos. It's not a big deal when you're used to it and are able to distinguish factory workmanship from someone's 50 year old sketchy hack repair/modification, but it can easily trip up a novice who hasn't heard about it before.