Found a Capehart

[Eric H]

Originally Posted by kbmuri

Interesting thought that the beam might be magnetically deflected right off the face of the tube. My assumption was that powering down the set caused the gun to fire briefly, but that it wasn't firing otherwise. Guess it could be shooting sideways instead. I'll have to mull it over a bit. Thanks for the thought.

- k

I'm guessing it might be a video problem keeping the tube in cutoff till you switch the set off.

Another possibility is the tube is so weak you can't see it till the sweep collapses into a single spot.
Have you tried viewing the screen in a dark room?

Also, it wouldn't hurt to run a small magnet around the neck of the tube to see if you can pull the beam into place long enough to see if it's working.

[kbmuri]

Eric -

Thanks. You're saying what I was saying, just you're using the proper terms and are more eloquent. "Beam not firing" is my clumsy code for "cutoff". Seems reasonable that if the beam were being pulled completely out of frame by a magnetic field, that field would collapse rather slowly when power was shut off, causing the "white line" to creep onto the field of vision. Instead it just appears in place, as though it were suddenly turned on.

I did try looking at it in the dark. No picture, even after several minutes of acclimating to the datkness. Then I shut off the set and the white line to white dot seemed startlingly bright.

Whe I said I put the TV "aside". I meant I put it back in the cabinet and placed the cabinet as a display-only lamp stand and knicknack shelf in my guest-room. Inconvenient to dig it all out now for further tests, but I'll definitely try the magnet trick later. Need to focus on one TV at a time, the Magnavox is up to bat right now. When I get back to this set later, I'll post more on it. Thanks for your input.

- k

[Tubejunke]

My 1958 Sylvania Electronic Products Technical Manual lists the 16RP4 as REQUIRING a single field ion trap. Here is the answer to your problem as long as you don't have a 16RP4A. "A" stands for aluminized which CAN mean no ion trap is required. I think the gun type plays a role with the aluminized tube. The ion trap is sometimes referred to as a "beam bender" because if you notice most sets with a trap have a kind of crooked gun. Hence the need for a "beam bender". What could have happened is the tube was rebuilt off of the aluminized bell with the older type gun maybe accidentally installed. I know one thing for sure a CRT that needs a trap will show NO raster at all.

You could put an ion trap in proper position and rotate it 360 deg. and see if you get a raster. If you do then make sure you adjust for maximum brightness.

The funny thing is that my manual makes note of both aluminized and non-aluminized tubes, while saying nothing about one of them NOT requiring an ion trap. Hmmm???

The only other things that come to mind are a bad crt socket connection (is the heater lit?) or a bad brightness potentiometer. Helpful hints I hope......

[kbmuri]

Ok, I pulled the set away from the wall and tried the magnet suggestions. First of all I have two Capehart CX33 chassis. One in this 325 and also one in my 333. It was the 333 that had the "USE NO ION TRAP" sticker, it has a 17BP4A. So I was wrong about saying for sure that the 16RP4 is aluminized, truth is I don't know. The 325 has a completely unmarked 16-inch tube, I presumed it's a 16RP4 as that's what the documents call for in this set. Maybe it's an A, maybe it isn't. Original owner says it worked at one point.

I "borrowed" the ion trap from the Magnavox's 10BP4. Installed it on the Capehart, rotated and slid it in every possible position and orientation, no raster of any kind anywhere. With the ion trap installed, in every orientation and position I tried, the white line and white dot never appeared when turning the set off. I took the ion trap back off. No raster again of course, but the white line and dot on power-off reappeared.

One would think that the resting white dot 4 or 5 seconds after power-off would not be being deflected, and would pretty much indicate the resting aim of the gun. Since it hits pretty near center without an ion trap, can I assume it's the type that doesn't need one?

I can't easily put the 333's 17BP4A into this chassis, the mounting hardware would have to change too. But I could probably put the 16RP4 into the 333 with a little padding to lift it up in front. That would certainly put an end to the issue of whether or not the 16RP4 is good or not, and if it's an ion-trap model or not. Might be worth doing. The 333 is on all original paper caps, and new electrolytics only bridged over the originals. It was something I tried 6 years ago without studying the science first. But it does produce a freaky kind of raster and snow. It would certainly test the other tube to my satisfaction.

I should probably pick up a CRT tester.

[Tubejunke]

Originally Posted by Tubejunke

My 1958 Sylvania Electronic Products Technical Manual lists the 16RP4 as REQUIRING a single field ion trap.

OK you will have to do this again because the 10BP4 uses what is known as a double ion trap magnet. The name says it all. It is basically two magnets connected together. Your tube calls for a SINGLE FIELD ION TRAP. Very different and for very different reasons. I'm not good enough to get real detailed on every application of the magnets but I know FOR SURE that the 10BP4 is the wrong magnet. I am not sure if the double magnet should have given some kind of raster or what. The specs for the double magnet are 35 Gausses which is the strength for the 16RP4. So the magnetic force is the same. However the single field strength is much more concentrated on the beam at only one point. The double spreads the force across a much broader area. I would say that if one were suitable for replacement of the other then there would never have been two types.

I would definitly try the correct magnet. Position the magnet almost directly over the first gap from the base (socket) of the gun. Rotate 360 deg. If all is well you should see something. Now if one of your sweep circuits is not working then it will be a bit harder to see what may just be a line.

This set from your description should work and this really sounds like an issue worth looking into.

Good luck....

[kbmuri]

Donald Randall -

Hey. Thanks for the photos. I should have looked down the page further in my Capehart Service Charts. The "William Penn" line was upgraded once in 1952, so there's an early version and a late version. Yours is the early version, with all the details as I described above. The later version (model number 9F212) had a CX36 chassis with a 21FP4 and a somewhat fancier cabinet. The William Penn in the eBay ad was the later model, so no surprise it doesn't completely resemble yours. Yours is definitely a 334, and the big Roundie tube is a real plus. Hope you get 'er going. Good luck!

- Kirk

[kbmuri]

Somebody working on a CX33, maybe 50 years ago.

[kbmuri]

Couldn't make anything happen with any magnets, any placement.

I found this item on eBay a couple of years ago for a buck or two, on the off-chance it might have a new 6U5/6G5 for a console tube radio I was restoring. Ended up having a useless 6AF6 so I set it aside and didn't give it any more thought. Suddenly realized it would be most helpful here. Turns out it's a pretty cool old TV serviceman's tool.

My capehart passes the first 4 bullets in the instruction sheet. Filament glows, Flourescent screen glows brightly, one side varies nicely with the brightness control. The other side stays fully closed regardless of any actions. Ergo, video is not present. I guess in hindsight I could have determined this with my 'scope by probing the CRT pins. Back in the day of house-calls, this was a 'scope in a pocket. Neat.

Again, I have too many open projects on my plate, so I'll defer any further work on the Capehart 'til some other things are out of the way. Magnavox TV is awaiting parts (in the mail, other thread), re-doing a Zenith Transoceanic radio as a favor real quick in the interim. Workbench won't hold another chassis.

-k

A few thoughts:
Obviously you don't need an ion trap magnet. Since you have a dot when the scanning stops, which indicates the electron beam is centered, hitting the screen. Without video, you should still have a full screen raster, so I would bet that the crt has low emission.. Without scanning, the electron beam is concentrated enough to make a dot, but when scanning it is spread out so thinly over the screen that it is not strong enough, (low emission), to cause the phosphors to glow like it does when it is concentrated in one spot. You might get a tube brightener from ebay and try it, or get a crt checker to check and if necessary rejuvenate the tube. After you get a raster, you can worry about video. Since you have a scope, you could check the video detector output and see if you have a signal there. You may not, since you don't have sound either. If not then the video and/or if/rf section would need to be checked. Since you checked voltages and found them to be correct, then I doubt that the crt is biased to cutoff, but you might recheck the grid to cathode voltage on the crt.
Donald
PS:
You can copy and paste this article on crt rejuvenation: file:///E:/Documents%20updated/Antique%20Radios/CRT's/crt_rej.htm

[kbmuri]

Ok, I had to research all this.

The 16RP4 and the 16RP4A both require ion traps. the "A" doesn't stand for "Aluminized", it just stands for "A", and the difference between a 16RP4 and a 16RP4A is unclear. The no-ion-trap replacement for a 16RP4 (or 16RP4A) is a 16RP4B. Only the "B" variant is aluminized (and therefore has a straight gun). For a while, I'm going to go on the assumption that my Capehart 325 has a 16RP4B (tube is unmarked).

The 17BP4 (as in my 333) is more complicated. The original 17BP4 has no aquadag external coating, no aluminized screen, and a clear glass faceplate. The "A" version has an external Aquadag coating. The "B" has the aquadag, and is aluminized. The "C" version has aquadag, is aluminized, and has a gray tinted glass faceplate. This forced me to go downstairs to the gameroom and pull the Capehart 333 away from the wall and reconfirm to myself the "USE NO ION TRAP" sticker, then search the tube for an ID. 17BP4B. So I was, again, guilty of making an assumption, above, that the tube in the 333 was a 17BP4A. It is not an "A", it's a "B". The "USE NO ION TRAP" sticker and the misinformation about the "A" suffix let me presume the rest. From now on, I give no more info "off the top of my head" here, but instead only after verifying and double-checking everything completely. It's important to speak PRECISELY when soliciting opinions here.

The 10BP4 and 10BP4A (as in my Magnavox) both require ion traps, the latter having a tinted windshield. But instead of a "10BP4B", the aluminized version is the 10FP4. No suffix. So you don't necessarily need a "B" suffix (or any suffix) to have aluminization going on. So the moral of the story, I guess, is to RTFM because simple naming conventions don't apply.

I was already misinformed about the "A"-meaning-aluminized rumor before hearing Tubejunke say it a couple of posts ago. I'm sure I read it here on the forum. Just need to make it clear that that's inaccurate and shouldn't be propagated in the future. A is just A. My sources: Sylvania Tube manual (1955), and Radio Shack Tube Substitution Guide (1975).

Other news, I found a Sencore CR-128 CRT Checker/Rejuvenator and a Sencore CG-135 Color Bar Generator at an electronics surplus store in Fort Wayne today, in the "junk heap". Ten bucks for the pair. Cool thing is they match the dimensions and layout of my Sencore TC-136 Tube Checker precisely, looks like I have a matching set. Haven't plugged either one in yet, as they contain a couple of electrolytics each. The CRT checker came with manual and setup guide, the manual having a schematic and parts list. So it should be a no-brainer to get it up and running (maybe yet tonight?). I'll settle the question on the Capehart 325's CRT shortly, that way, if it works and if I can get a "feel" for its accuracy (I have a couple of "NOS" tubes to check against, and one or two untested but well-used-looking CRTs too). My gut feel is that the 325's CRT is fine, based on the original owner's stories, But only an objective test will tell.

The Color-Bar Generator has no manual. Usage is probably completely intuitive, and I don't plan on working on a color set any time in the near future, so no great loss, but if anybody out there has a manual, please let me know.


Small aside, Donald, I'm sure you saved the rejuvenation article to your local PC, then shortcutted to it locally, rather than on the web. The link you provided points to a file on your "E" drive, and is therefore unavailable to anyone but yourself. If you highly recommend the article, I'll need to know where, on the web, you originally found it. Otherwise, thanks a bunch for your suggestions. I'll try them as time allows.

- Kirk

Actually, I found that file directly from Google. I made sure it worked before I sent it, you need to be sure to copy and paste all of it, starting with "file" and ending with "htm". However, I just now went to the file and backtracked to this url: http://www.thevalvepage.com/teletech/teletech.htm With it, you may find additional interesting articles.

Another thought occured to me. Perhaps inadequate high voltage to the anode of the crt would decrease the emission giving the same results as a weak crt.
Donald

[Tubejunke]

Originally Posted by kbmuri

Ok, I had to research all this.
I was already misinformed about the "A"-meaning-aluminized rumor before hearing Tubejunke say it a couple of posts ago. I'm sure I read it here on the forum. Just need to make it clear that that's inaccurate and shouldn't be propagated in the future. A is just A. My sources: Sylvania Tube manual (1955), and Radio Shack Tube Substitution Guide (1975).- Kirk

Man you need to chill out and thank your lucky stars to be a part of a group of people who at least give a rats a** about your problem. If this were a be perfectly correct all the time forum, what would we have? I love the way many of us simply give educated guesses (some uneducated) just trying to help someone with a clue as to what is going on with a given situation.

Sure now I could see somebody getting steamed if someone led them into physical harm or something. Man, nobody told you to place the HV anode to the crt in your mouth to check for low voltage. Did they?

The craziest part is the fact that we are both using some of the same information and also have some of the same conclusions. AGAIN my info comes from my 4th printed revised edition of the Sylvania Electronic Products Technical Manual-1958

I will state what is clearly said in this very informative manual. The 16RP4 in ANY form is a tube that needs a 35 Gaus, single field ion trap magnet. "The Sylvania type 16RP4A is identical to the 16RP4 except for having an aluminized screen". What I make out of studying this manual is also that "A" does not necessarily mean aluminized. Again case in point the 10BP4A for instance has what is refered to as a "gray filter glass faceplate". No mention of aluminization. Also, I have found out the fact that just because a given tube may be aluminized does not mean that it has a "straight gun" and therefore needs no ion trap.

There is absolutely nothing that says that if a tube has an aluminized screen then no trap is required. Now there are many tubes that were built specifically to NOT require an ion trap. I am fairly certain that ion traps kind of faded out with the 50's. I myself, due to misinformation thought for a long time that if a tube had an aluminized screen than it DID NOT require a trap. I didn't get all bent out of shape about it. Really the person led me toward learning more about the whole ion trap mystery. Double field, single field, needed, not needed ect...

So I think it is an insult to everyone to imply that everyone should refrain from saying anything to try to help anyone unless it is verifyable as being BY THE BOOK. I'm not saying I have never made an incorrect statement on this forum but the Sylvania info is as by the book as it gets. Now there is a possibility of tech books not being completely clear but in this case I doubt it.

So SORRY if my attemt to lend a hand and do some free research did not fix your problem. Evidently some other idiot made the same mistake before me. I think I can speak for both of us and say sorry pal.... I WONT try it again.....

[kbmuri]

Hey, tube.

Please re-read my comments. I was castigating myself for MY not speaking clearly when I was speaking (i.e. "soliciting advice"). I was a bit angry at myself for not reporting the tube number right in my 333, and also for originally reporting that the "use no ion trap" sticker was in my 325 when it wasn't. I chided myself somewhat and then vowed to "speak more precisely" in the future. At NO POINT did I criticize a single word of yours. At no point did I imply that anyone else should refrain from saying anything. I was only speaking about myself. Please re-read my comments and tell me where I asked anyone (other than myself) not to say anything about anything at anytime, ever. I thought that was clear. If it was not, I sincerely apologize. To you and to the forum.

Please lighten up. I had no ill will whatsoever in any of my writing, I have none now. I clearly appreciated your comments and I believe I thanked you for them in several places. I'm glad you told me what you know about single-field ion traps vs. double-field ion traps vs. no trap at all, and when and where and why you thought each was necessary. I thought that letting you know (and others know) that magnets weren't working in my situation was helpful, informative, and perhaps entertaining information, both to you and to others. Should I have lied and said the magnets worked, just to make you feel good about yourself? Are you so insecure that when I doublechecked your facts against a book (and found your original statement to be wrong) that you have to lash out, call people "idiot", and then refuse to ever lend a hand ever again? This is the behavior of a kindergartner.

Not entirely sure I'm the one who needs to "chill out".

In your rant above, you say that "what you make out of studying the manual" is that "A does not necessarily mean aluminized". Two posts earlier you said "A stands for aluminized". Complete contradiction, both stated as fact. I found out from independent study that A does not mean aluminized. I believe we completely agree on that question now. I don't think we did earlier. I was simply clarifying. Should I have not pointed out your earlier statement? Should I have let a third pary or fourth party or fifth party read the statement and use the information? Or was it so much of an offense to point out the error that I should have just remained silent, so as not to disturb your fragile ego? Really? I'm sorry if pointing out a misstatement caused you such grief that you felt you had to jump all down my throat for doing so. Really, I was just trying to advance the understanding for everyone. I guess that was wrong. Sorry, everyone else, for correcting Tubejunke on a mistake. We should never do that. Ever.

In fact I was just part of the caring group of people who gives a rat's a** about the next guy down the line who might have had the same problem.

I don't think this forum is for children to cry foul and act injured and make silly threats. Please don't call me "pal". Farthest thing from. If you "WONT try it again", don't. Free country. Sorry I bothered you. Really didn't mean to.

Thanks for sucking all the air out of the room. This place was fun, now it's not.

[Chad Hauris]

One sign of a tube that needs an ion trap is that the electron gun is angled.
There might be some non-angled that need the trap, but the angled gun tubes always need the trap to bend the electron stream back straight.