View Full Version : Found a Capehart


RetroHacker
04-29-2006, 06:33 AM
This was a trash find - I was tipped off by someone on the local FreeCycle list - the post was "Spotted: 1940's console television" or something like that. So, of course, I raced over there, and sure enough, it was near the intersection, just like they had described. It was in decent shape, no knobs - and when I went to lift it, the chassis was loose in the cabinet, which made it a lot easier to move... I managed to get the set in my Toyota Camry - I had the chassis in the front seat, and the cabinet standing in the trunk, with cardboard to pad it from the trunk lid and the frame of the trunk, and tied down with old telephone wire I had in the car. Anyway, there's no workspace at the house right now, so I stashed the set in my storage locker. I took some pictures though, thought you guys would like to see it. On the back of the cabinet, the sticker says it's a model 332, but someone crossed out the 2 and wrote in a 3 with a pencil, and the chassis is marked with pencil as being a Capehart 333. Perhaps an upgrade or circuit change, or someone swapped chassis at some point? The chassis is pretty dirty, and there is a little rust. The picture tube base is cracked, but the tube appears to still have vaccuum. I'm not sure what kind of picture tube is in here, it's not labeled, and the tube chart says to only replace with a Farnsworth 170-AR. The cabinet is in decent shape, a few good scars on the top, and some of the veneer is coming loose, but it's real wood, and in overall pretty good shape. The front escucion thing the goes over some of the picture controls is missing, as are the knobs, but I'll worry about those when I have time to work on the set. Overall, a pretty good score for the side of the road.

-Ian

rp2813
05-03-2006, 01:12 PM
Hacker, my experience has been that there's not a whole lot of interest in Capeharts. I have my family's original set, a Capehart 325-F (appx 1951), put a new CRT in it back in the early 70's thinking I'd use it in my bedroom when I still lived at home, but the set had more problems than a new CRT resolved and running it with a shrunken picture only created an uneven burn-in on the new CRT so I abandoned the project. My expertise didn't go much beyond changing out tubes then, and it still doesn't now. The set needs a re-cap at the very least but I have no place to put it once it's brought back to working condition so for now it just sits. Debating on whether it would be easier to sell (if I decide to) in working condition with a recap, or as is. I did put up a post looking for knobs and got a guy who found some for me so you may get lucky with knobs for your set too.

kbmuri
05-10-2006, 08:11 AM
Great catch on the Capehart 333. The picture tube number you're wondering about is 17BP4, still occasionally available on eBay or thru antique electronics dealers. Your set was sold in 1950, and was called the "Blue Ridge" model. There isn't a Sams schematic sheet for it, but the schematic for the 325-F is pretty close. Look for Sams sheet 112, Folder 3 (11/1950). Capehart-Farnsworth put out a set of service documents for it that's more useful, but really hard to come by. Here is a photo of my 333, as I found it. It's currently in pieces, under repair. Until now I thought it was the only one left. Despite the "lack of interest" (some perceive) in Capehart sets, you should give your set the attention it deserves. It's certainly an unusual item practically nobody else will have. I found mine 5 years ago, yours is the only other identical one I've come across.

wa2ise
05-10-2006, 02:28 PM
Hacker, my experience has been that there's not a whole lot of interest in Capeharts. I have my family's original set, a Capehart 325-F (appx 1951), put a new CRT in it back in the early 70's thinking I'd use it in my bedroom when I still lived at home, but the set had more problems than a new CRT resolved and running it with a shrunken picture only created an uneven burn-in on the new CRT so I abandoned the project.

You might be able to remove the B&W CRT burn in by running the CRT with a full white raster for about 100 hours or so. Brand new phosper will dim about 10% in the first 100 hours or so if use, and then stay about level for the next several thousand hours. The idea here is to get the unused phosper (that which was outside the shrunken picture area) past the 100 hour use to get it about the same light emitting level as the burnt in area.

rp2813
05-11-2006, 12:22 PM
Thanks for the advice on the burn-in issue. I can tell you right now that this set didn't run for anywhere near 100 hours after the new CRT. It only took it a few minutes for the pic to go all distorted so it wasn't worth watching for any length of time that way.

If I had the room, I'd have this set fixed (I know of local guy who would do it) because I know it would give a great pic and sound once it's working right. I've only seen one other 325-F and that was on eBay within the last several months. Don't know if it sold, or if it did, for how much.

Also, the set needed both the on/off and channel knobs and one guy was able to find them for me. Found that on the channel knob, the numbers only go around it half way, the other half of the knob is blank, as if once you hit channel 13, you have to go backwards instead of continuing in the same rotational direction to channel 2. This is apparently how Capehart designed some of their sets, as even the owner's manual for the 325-F set shows that kind of configuration on the knob, but the actual (and original) tuner on this set rotates all the way around and calls for a knob that has the channel numbers evenly placed around the entire knob, not just on one side of it. If anybody knows where I can find the right selector knob for this set, please let me know: [email protected]

If I do decide to restore the set the tuner will likely stay on channel 3 or 4 so it can be run by cable converter, so the knob issue wouldn't be the end of the world, but it would be nice to have the right one if it can be found. No small task.

kbmuri
05-13-2006, 09:59 PM
Here's a shot of my 325 with a fresh set of orange drops and power caps. A few resistors are still out of tolerance, but it's pretty close to power-on tests. Also, here are a couple of scans of the technical documents for this set. I have electronic copies of them available if anyone is interested.

Hacker, looking at your photos I see the ten-watt voltage-divider (resistor) mounted to the chassis of your set (very bottom of your photo) is broken. You'll need to replace that before you even think about applying power. Catastrophe otherwise. Besides that, the bottom of the chassis looks really clean and you should be able to restore it.

Finally, if either of you two feel like you are going to sell your sets rather than restore them, give me a heads up. Thanks.

rp2813
05-19-2006, 11:33 AM
KB, just wondering, in your experience with TV restoration, how does Capehart compare with other makes for overall quality of picture and sound? Is it noticeably superior? These sets weren't cheap when new. It's hard for me to judge picture quality on an old BW set. I've become so used to watching bright and clear color resolution on the modern sets around my house, I no longer remember what a B&W set should look like at optimum performance. I have a recapped Admiral 20X12 set that's hooked up to cable with a converter tuner and has high contrast on some stations and low on others (this may be an AGC/DC restoration issue) and when it's tuned to a high contrast station you can't see a lot of detail because objects show up as solid black. I keep controls adjusted to some middle ground so the low contrast stations don't show up with thin diagonal lines, which to me is more annoying than high contrast. Is this typical of early TV behavior or would a Capehart with AGC give steady resolution on all channels? I'm trying to decide if I'll ever want to restore the 325F, and knowing whether it would be watchable and that I wouldn't have to be fiddling with the adjusting knobs all the time would help me with this decision. I've gotta make my case with a spouse who likely doesn't want a hulking cabinet with obsolete entertainment taking up valuable space in the house, so would like to get your opinion on Capehart vs other makes.

7"estatdef
05-19-2006, 04:53 PM
Hey Rp you may want to give this a try to cure the retrace lines.
http://groups.google.com/group/rec.antiques.radio+phono/browse_thread/thread/4081fb46a31772eb?hl=en&lr=&safe=off&frame=right&seekm=e65bfe39.0207011623.

Worked fine on my 20X12
Terry

rp2813
05-22-2006, 02:32 PM
Thanks Terry,

I printed out some DC restoration info on this set a while back that apparently indicated Admiral put out a service bulletin of some kind on how to resolve the retrace line issue. I'm assuming from what I've read here that retrace lines are the somewhat faint diagonal lines, on my 10" screen there are probably 3 or 4 of them appearing with quite a bit of space in between them, and not some other type of line phenomenon. They generally appear during dark screen periods between scenes or commercials.

I'm going to print up the info off of the link you provided and save that also, as I intend to take this set to the guy who recapped it at some point, and have him make the necessary fixes to get rid of the lines.

Thanks again for that link--I didn't know about that group.

Ralph

Whirled One
05-22-2006, 07:51 PM
KB, just wondering, in your experience with TV restoration, how does Capehart compare with other makes for overall quality of picture and sound? Is it noticeably superior? These sets weren't cheap when new.

I dunno about their TV sets, but Capehart was primarily known for their line of console phonos and radio/phono combinations in the 1930's and 40's. Their biggest claim-to-fame was an amazingly elaborate record changer that could automatically play both sides of each record in a stack-- in sequence-- and still even intermix record sizes automatically. I've seen one of these changers in action once; it's a facinating Rube Goldberg device. The thing was pretty much done in by the introduction of the LP, though, since the original mechanism was designed for 78's only, and while Capehart did eventually adapt it for LP's, the convenience/desire for such an elaborate record changer wasn't as high for LP's than it was for 78's.

Phil Nelson
05-23-2006, 11:40 AM
I dunno about their TV sets, but Capehart was primarily known for their line of console phonos and radio/phono combinations in the 1930's and 40's.

High-end Capehart radios were high quality and quite expensive. I believe the postwar Panamuse had 25 tubes.

bgadow
05-23-2006, 12:04 PM
I have a preware Panamuse, a little rough but worth saving. Quite a set, HEAVY, I haven't been able to find much out about it. A project for another day. I should look at the record changer-never really payed much attention to it. I have it sitting between a pair of nice Stromberg-Carlson's and it looks right at home.

At some point Capehart & Farnsworth went together and slowly the quality level drifted downward. This trait was not unique to that company. The TV business became very competitive and by the early fifties there was not much of a market for "overbuilt" sets. This is illustrated by the late fifties Scott in the other thread; the same thing happened with DuMont-in 1950 they were real tanks with a unique design; by 1960 they were rebadged Emersons. By the mid-70s all those names were showing up on cheap stereos like you would buy at Kmart. I have a number of service manuals somewhere for Capehart am/fm/8tracks.

Jeffhs
05-23-2006, 09:56 PM
My great-aunts had a Capehart 16" round-tube console TV in the 1950s. When they got a new Motorola portable b&w set in the early sixties, they gave me the Capehart, which I had in my bedroom for several years when I was a kid. The set worked well, IIRC, even in the near-fringe TV reception area I lived in at the time, but something has always puzzled me about its power cord. I remember it was about ten feet(!) long and had a circuit in a small metal box right in the middle of it (the circuit in the box was in series with the cord); the box ordinarily sat in the base of the console cabinet. I had almost forgotten about that until I spotted this Capehart TV thread; now I'm starting to wonder again, almost 40 years later. An interference filter, perhaps? :dunno: :scratch2:

I kept the cabinet for years after the TV went West and made a storage cabinet of it--this was several years before I ever got interested in collecting old TVs and long before there was any such thing as the Internet or AK. Had I gotten this set later on, say in the late sixties or early 1970s (before I moved the first time), I no doubt would have tried to repair the Capehart chassis.

kbmuri
05-24-2006, 02:33 PM
Jeffhs,

I would hazard a guess that the box in-line with the power cord was a voltage-boosting transformer/regulator. TVs like your old Capehart performed pretty poorly to rural power service of the day, which tended to be a little low by the time it made it all the way out to the farm. The delivery/setup guy would have installed the booster to gain a little voltage (at the sacrifice of drawing a little more current) to make the TV perform like it did in the showroom.

This is just a hunch, though, without a more thorough description.

RP,

Spousal negotiations notwithstanding, I think you'll find the Capehart 325's picture to be as good as any set of the day. None of them will be a 42-inch plasma HDTV, but if you want the nostalgia of a quality B/W set, you've got a solid performer. I wouldn't expect any difference in contrast between stations, if it's restored well. Your Admiral's trouble does sound a little like AGC, but I've read that some of the cheaper early sets just did that. I have some reference material I'll post (if I can find it) that might help.

Everyone else,

Capehart made the finest equipment imagineable in the '30s and '40s. So did Farnsworth, although Farnsworth had more of an eye for the common-man's budget. It wasn't 'til they both merged with ITT that they started putting out garbage. I think that was around 1960. The Capehart TVs of circa 1950 are pretty top-of-the-line items. IMHO.

Oh, if anybody has a Capehart roundie or knows of one for sale, post it here please. Thanks. Sorry, Jeff, to hear you had one and lost track of it. :tears:

rp2813
06-08-2006, 01:50 PM
Well KB, I've seen a few posts that indicate you are a real Capehart fan. The 325-F I've got might be up for grabs at some point if I decide not to have it restored. It's not a roundie but I get the impression you might be able to come up with an interested party for it. Not ready to part with it just yet, but wanted you to know it's in California. Don't know where you are, but I think this set is one that would be prohibitively expensive to ship and have seen too many horror stories about damage so it would probably have to be picked up. Since it was my family's first TV, there's some sentimental value and that's why I'm still not ready to let it go. You can e-mail me directly if you want to discuss more: [email protected].
Thanks,
Ralph

kbmuri
06-10-2006, 09:03 PM
rp,

I'm in Fort Wayne Indiana. Look on the back of your set, you'll see that's where it was built. I started picking up local things of interest on eBay a few years ago, the Capehart and Farnsworth items appeal to me for that reason, although I just bought a Zenith console from 1951, so it's not cast in stone that I'm only a Capehart fan.

Probably not possible to get your 325 here in one piece on a budget, but I guess keep an open mind. Attached is a pic of my 325. I bought it last fall off of eBay, this is one of the ad photos. It's already in pieces, so I can't get a good shot right now. It's proven to be an agonizingly difficult fix, but I'm getting there -- with the guidance of a master/mentor from New Jersey who's coaching me thru it over email. Pretty cool, this internet thing. Pictures will be posted when it's restored and running.

I really like this forum -- I only discovered it a couple of weeks ago. It's been a help, mostly in inspiration/motivation and knowing there are others like me out there...

-kb

polaraman
07-25-2006, 10:59 PM
Another Capehart on Ebay. A real nice looking TV set.


polaraman

http://cgi.ebay.com/Capehart-Television-Vintage-Antique-Capehart-Farnsworth_W0QQitemZ280010819824QQihZ018QQcategory Z3638QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

kbmuri
07-26-2006, 11:04 PM
It's in the Milwaukee area. It's a keeper, IMHO, but not at the price of driving through Chicago again. There are a few Wisconsin AKers here, hope one of them saves it from the fish tank...

rp2813
07-31-2006, 10:35 AM
Hey KB, I sent you another PM. If you're like me, you may not be noticing that you got one.

Ralph

Tubejunke
07-31-2006, 09:11 PM
I dont know where anybody got the idea that the old Capeharts are considered undesireable. I have always thought DuMont, Capehart, and Sparton were some of the best made and most interesting sets of the 40's-50's.

If anybody believes it I have an early 50s Sparton that a man used to watch all day Sat-Sun while sitting at his flea market table back when I was about 12 years old. It was not for sale. Even then I thought it was cool looking compared to the 60's and 70's crap that had flooded the market by that time. I think it took me till I was nearly 14 to talk the man into selling. I gave either $10 or $15 for the set.

Long story short I am 37 years old now and I can go into the next room and watch this set with as crisp of a picture as I have ever seen. Original caps even. It has developed some vertical shrinkage after about 30 min. Probably (surely) cap time. We just DONT make products like these any more.

By the way I have a Capehart owners/service packet for Models 322M & 322B. This is super cool. There is operating instructions, installation and setup instructions w/test patterns, a post paid envelope to Capehart-Farnsworth, 2 service updates, a schematic, and the neatest thing, a letter to congradulate the new owner, and another letter to tell the service man asking that he insure that the set is set up in an "acceptable" manner. Really neat stuff!! To bad I don't have a set to go with it. I was thinking of putting them on Ebay but I just havent had the time. So if anybody needs this stuff PM me.


Oh yeah, if anybody has any undesireable Capeharts in the way I will remove for FREE!!

Tube out.......

kbmuri
07-31-2006, 10:09 PM
That eBay Capehart didn't even get a bid for $50. I was sincere about not wanting to spend 5 hours in the 40-square-mile parking lot known as Chicago. Maybe it'll relist.

I have a hand-signed letter dated April 11, 1956 from the Capehart-Farnsworth company to a repairman in Wisconsin, with materials to aid him in servicing a broken 661-P. Probably a similar service packet.

There was a packet on eBay this week for a 324. I put a couple bucks on it, pretty sure that would be enough, didn't think anybody else would be interested, but somebody sniped me and got it for $2.25. I shoulda put a fiver or ten on it.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280010895130

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280010819824

Tubejunke
08-01-2006, 08:41 PM
Gosh, I would think such info would command at least a $10 or $20 bill. To me the info is more rare than the set in a way. I mean how many service packets or other paperwork (I guess today its a bilingual owners manual and a rebate form) has anyone saved from sets you are currently using everyday. Probably very few. The sets outlast the paperwork.

Still in all none of the stuff is a goldmine. Most TV people are just having fun. None of us are getting rich. Like restoring an antique car, you are only helping in the preservation of something nice from the past. Your not gonna turn a big profit unless you can afford to keep the thing in dry storage for 20 years. Other than that if you more or less break even when you decide to move something you are doing good.

I'm kind of glad TV stuff is not going through the roof. If it were there would not be as many people able to participate.

kbmuri
08-02-2006, 11:35 PM
Tubejunke -

Couldn't agree more!

- k

Donald Randall
08-03-2006, 08:24 PM
Hey k,
I'm the one who sniped you. I recently bought a model 334 Capehart at a local flea market, Oklahoma City, and I am looking for information. Actually, I bid $31.00 just to be sure I would get it, figuring I could sell it on ebay later for whatever it cost, or close enough. I'm not collecting old literature, so when this package arrives, I will scan it and let you have the originals if you want. I've been watching for a Sam's photofact, 112-3 on ebay, but no luck so far. You can bet one will show up eventually though.
Donald Randall
PS: If it were for the model 334 I would keep it with the television, I believe it has the cx33 chassis so I just wanted it for the information in this case. DR

kbmuri
08-04-2006, 02:10 PM
Donald -

Not a problem. Glad the documents are in good hands (an AKer).

Your 334 is a particularly nice set. You're correct it has a CX33 chassis. It should have a full-door cabinet in mahogany. The chassis number is C303, It should have a 16GP4 CRT, electromagnetic focus. A 12-inch speaker, standard-coil (turret) tuner. It was marketed as the "William Penn" model. Circa 1952. It should be a fun set to work on.

I was really hoping by now to be able to post pix of my 325 working. I replaced every capacitor in the set. Verified all resistances, visually checked everything a hundred times over. Black screen and silence being my only reward. I had to put it aside for awhile out of frustration. I'll get back to it later, switched gears and started working on a neat little Magnavox roundie instead (another thread here).

The schematic you'll be getting in the 324 Owner's packet will be fairly accurate, but will probably be missing 2 years worth of production-run changes. Several circuits will be confusing to you, if you're comparing the schematic to the device. I've got all that documented if you need it. That schematic also doesn't include the tuner, as various tuners were used in the 324. I guess rather than have the wrong tuner specified, or having to maintain different documents, it was easier for Capehart to just leave it out.

Post your email address if you want, or send me a PM with it. I can send you some hi-res scans, if you're interested.

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170014673971

Of course, if you can post progress on it here, please do so.

- k

rld-tv01
08-04-2006, 06:45 PM
Tubejunke,

I spotted a Capehart tabletop in a Lexington VA antique mall about a month ago. It was green leatherette with two big yellow knobs and the name Capehart across the front. It looked like it was in brand new condition. Everyone walking by it was commenting on it. I think it was about 1951-1952 since it had a 15 inch screen. It may have been the tv in this add on eBay http://cgi.ebay.com/CAPEHART-Television-RARE-1950s-Color-PROMOTIONAL-ADVERT_W0QQitemZ250013555443QQihZ015QQcategoryZ378 35QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
If interested I can supply the name of the mall. There was no price on it and I didn't ask. I also passed up an 1948 Admiral radio TV phonograph console for $100 in Harrisonburg VA on the way down on the same trip. I was driving my mustang. I don't pass up every tv, I have about 54 TVs now so I am more selective. I got two transvision cabinettes last week. A 7" one on ebay and a 10" one the same day from Harry Poster. I was searching for a chassis for the 7" cabinet and found Harry listed the 10" one right before I did a google search for Transvision. Both are cool art deco cabinets.

Tubejunke
08-04-2006, 08:53 PM
Thanks for the tip rldtvo1 but I think I will leave that alone. If it were a double-d roundie at a decent price I might have to consider the maybe 2.5 hr. ride (1 direction). The price of gas is a big factor in going out of town for anything.

Not that I'm that poor but frankly I don't like lining the pockets of the evil oil men. Record profits my friends. Their not completely lying to us, their doing it right under our noses. No wonder we don't need our industrial base anymore in America. Sell what's left/ousource everything and the oil elite can simply give every middle class and poor LEGAL citizen a $20,000 check annualy, TAX FREE. These people would introduce the money back into the economy and everything would work out fine. "Vote for me, and I'll set you free":)

Sorry for the rant...I just watched the news:(

To Kbmuri, I know how you feel on the restore job with very bad results. I had the same experience on a 1958 Zenith Space Command. I replaced most of the capacitors (all of the electrolytics and most of the paper) and had absolutely NO progress toward a working set. Nothing changed!! I had to set THAT to the side for a couple of years! Only lately have I thought about diving into that one again. One would think if you checked or replaced every component in a set that it would work. I guess I'll follow each and every wire and component to check for something misconnected.

kbmuri
08-04-2006, 10:11 PM
Too far away for TubeJunke at 5 hrs on the road = WAY too far away for me (20 hours?). The green leatherette sounds intriguing, but strikes me as likely an after-the-fact art project. My documents are very thorough thru 1956 or so, nothing mentioned anywhere about leather or vinyl coverings.

The tabletop model in the eBay ad is a 321, same chassis and knobs and CRT as my (and Ralph's) 325. Just a smaller cabinet.

Worst part about my 325 is just that it might be down to that one last mystery, that if I solved it, it would work perfectly. After recapping the electrolytics I checked every plus-side of each with a 'scope against the voltages called for in the Sams sheet, and everything there is in order, with negligible hum. The original owner told me the CRT was good, and had low hours on it, and I'm inclined to agree by the looks of it, but maybe it's not. Full orange-drop replacement of all the paper caps. Also replaced the 20,000-Volt doorknob and the 6000-Volt flyback-to-ground cap. Oh, and 23 NOS vacuum tubes, all tested 100%. In general, taking scope readings at test points all-around seems to result in reasonable readings. No "dead sections" anywhere.

I should say that when you turn it on, nothing happens. It can be left on for hours with no smoke or overheat. The CRT face will raise the hairs on the back of my hand, as if there's hi-Voltage present (I don't have a hi-voltage probe to be 100% certain just how high, but the screen "crackle" seems right). When I shut the set off, I get a white line from 90% left to 90% right, a few inches higher than centered, which shrinks to the known-and-loved white dot which then fades away normally. That's the only indication it's probably a working CRT. The error has to be somewhere else. It's a mystery, and like I said, shelved for awhile 'til I can work up the motivation to dig harder.

wa2ise
08-04-2006, 10:33 PM
Worst part about my 325 is just that it might be down to that one last mystery, that if I solved it, it would work perfectly.
I should say that when you turn it on, nothing happens. It can be left on for hours with no smoke or overheat. The CRT face will raise the hairs on the back of my hand, as if there's hi-Voltage present (I don't have a hi-voltage probe to be 100% certain just how high, but the screen "crackle" seems right). When I shut the set off, I get a white line from 90% left to 90% right, a few inches higher than centered, which shrinks to the known-and-loved white dot which then fades away normally. That's the only indication it's probably a working CRT. The error has to be somewhere else. It's a mystery, and like I said, shelved for awhile 'til I can work up the motivation to dig harder.


Maybe there should be an ion trap that is mis adjusted or missing? An ion trap is a magnet device clamped to the neck of the CRT an inch or two between the yoke and the CRT tube socket. You might be able to see by way of dust marks where it should reside. try moving it back and forth, and rotate it as well.

An ion trap is a device that is intended to steer the electrons to hit the phospers on the face plate but to steer to a much lesser amount heavier negatively charged atomic ions away from the faceplate and to get trapped locally in the electron gun structure. Without the ion trap magnet everything gets trapped.

kbmuri
08-04-2006, 10:55 PM
The original Farnsworth 160-AR tube is long gone. Has a replacement 16RP4 that's aluminized and says "Use NO Ion Trap" in bold letters. The original ion trap probably left with the original tube. Nothing on the neck now.

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

Eric H
08-04-2006, 11:26 PM
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
08-05-2006, 10:00 PM
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
08-05-2006, 11:47 PM
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
08-06-2006, 02:14 PM
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
08-07-2006, 09:43 PM
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
08-12-2006, 07:54 PM
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
08-12-2006, 08:02 PM
Somebody working on a CX33, maybe 50 years ago.

kbmuri
08-12-2006, 09:17 PM
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

Donald Randall
08-13-2006, 01:00 PM
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
08-15-2006, 10:02 PM
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

Donald Randall
08-16-2006, 08:02 AM
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.

Donald Randall
08-16-2006, 06:32 PM
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
08-17-2006, 09:33 PM
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
08-17-2006, 10:40 PM
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
08-17-2006, 10:43 PM
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.

Eric H
08-18-2006, 12:08 AM
Guys, are we both having a bad day?

"I was already misinformed about the "A"-meaning-aluminized rumor before hearing Tubejunke say it a couple of posts ago"

Yes, this could be taken the wrong way but I don't think it was intended as an insult.

Kbmuri you responded with a rant that was equally nasty.

Can we all just take a deep breath and relax a little. it's supposed to be fun. :yes:

Jeffhs
08-18-2006, 01:39 AM
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".



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.


kbmuri - I also read tubejunke's reply and agree with you 100 percent. Without going into details, I learned my lesson as to shooting my mouth off in these forums long ago. I have been corrected many times for inaccuracies in my answers to posts--and I took it all like a man. I'm far from an expert when it comes to electronics (just in it as a hobby, not a business) and not afraid to admit it. I know very little about the solid-state technology everything in electronics employs these days, as almost all my experience in electronics, in over four decades of experimenting and 34 years in amateur (ham) radio, has been with tube-powered equipment; if I should make a comment in a post to any of these forums that may be anywhere from a little bit to totally wrong, I will welcome the correction. The longer I read these posts in the various AK forums, the more I learn about electronics, both vintage/antique and solid state. I have made it my business since joining AK not to respond to a post unless I am reasonably certain that my comments will be of some help. If I know nothing about the subject under discussion, I write nothing and read other posts, in hopes of learning a thing or two. Sometimes my answers to threads I do reply to may be a bit off the mark, but if they are, as I said above, I will welcome corrections.

I also agree with your comment that we don't need that kind of childish behavior here (getting all bent out of shape just because someone corrects you or outright calls you out on a comment you make in a post to an AK forum). I think tubejunke would be a lot better off in this forum, and any others within AK to which he may post, if he would adopt the same attitude, i. e. welcoming corrections if information in one of his posts is inaccurate or incorrect, without snapping the respondent's head off. We all goof once in a while; none of us is perfect. Just a thought. :yes:

Donald Randall
08-18-2006, 10:42 AM
As I understand it from electronics school many years ago, (44 years ago), plus a recent review: An aluminized crt does not have a gun with an ion trap and does not require an ion trap magnet. The electron beam has ions mixed in with it that will damage the screen phosphors causing a dark spot in the center of the screen. The very thin aluminum coating has many tiny openings in it which will pass the electrons but will not pass the ions which are of a much greater mass. On a non-aluminized crt, an ion trap, (bent gun, tilted gun, or tilted electrostatic field) aims the electron-ion beam towards the side of the crt neck, or in some, the side of the second anode. The ion trap magnet is used to deflect the electron beam back to center but will have little effect on the ion stream which hits the inner side of the anode, or the side of the neck. If you have a spot of light or a raster on the screen without an ion trap magnet, then obviously you don't need a magnet to straighten the beam. You don't need an ion trap with an electrostatically deflected crt, because the electrostatic field will deflect the ions as well as the electrons, and the ions won't be concentrated in the center of the screen and damage it.
Donald

Tubejunke
08-18-2006, 09:23 PM
Hey, tube.
I thought that was clear. If it was not, I sincerely apologize. To you and to the forum.

I don't think this forum is for children to cry foul and act injured and make silly threats. This place was fun, now it's not.

I looks as if we both need to just take a second look at what we are doing. I did go back and look at the comment that sent me into my "rant" and I can see at least that I over reacted in an unacceptable way. I am glad to know that at least one person who read the whole mess could conceive HOW someone might take the statement with my name in it in offense. Still the same my reaction was wrong.

I stick with my guns on my position that this forum should not be thought of as a place where you have to be "precise" in order to be welcome. Also,I may have reacted in a childish way but I didnt make ANY "threats".

I think kbmuri and I have now stood in each others shoes in a way. I will say his very bad reaction was at least more justified than mine. Just as cutting though for what started out as an apologie. I dished out the mess, so I should take it. I will accept my mistake, apologize, take my licks, and hope everyone here including kbmuri can forgive and forget. In my defense I say that I have several hundred posts and never had a bad word with anyone. No excuse, just trying to clarify the whole matter in a fair way for everyone. I think I have been watching the world news too much. There may be a bigger lesson to learn here than we think. Ecpecially if you watch the world news.

Personally, I love to learn the ropes of our hobby, I have MANY times found that I was completely off base. After many years of interest and tinkering I am finally getting to where I am HALF decent at it. The whole aluminized issue is a prime evample. In the few days between some of my posts on this thread I had learned that "A" IS NOT a guarantee that a tube is aluminized. I was wrong if I said anything different. I was given that info here I think. Completely wrong. The thing that I think confuses the issue is the fact that if a tube has NO extended call letter like "A" or "B" then it WILL NOT be aluminized. In other words the aluminized tubes all have an extra call letter, either "A" or "B" or possibly something else. The extra call letter just signifies something other than the plain P4 phosphur, clear glass faceplate. The way the book reads none of this is a decisive factor as to weather or not an ion trap is used.

This is what I make of the whole thing based on my research.

Again folks sorry for my stupidity. I really was an idiot weather kbmuri implied it or not.

We live and we learn by our mistakes.....

Tube out.........

rp2813
09-06-2006, 03:11 PM
Hey KB, if you're still checking out this thread here's some information from a totally amatuer non-electronically inclined guy whose abilities don't go past changing out tubes (but NOT CRT's--that whole high voltage thing scares me too much) and making adjustments.

My 325 had an ion trap originally and still does after having its CRT replaced many years ago, and I know it's necessary because adjusting it does have an impact on brightness. I think yours probably needs one. Not saying that will fix your problem, but I'm guessing once the problem has been solved, an ion trap will need to be a part of the finished and working product.

I'm considering a re-cap of my 325 by a local vintage TV/radio guy but am thinking even in working condition I probably wouldn't recover my costs when the set eventually goes up for grabs. And there's that open issue around the wrong channel selector knob. . .

Tom_Ryan
09-08-2006, 04:44 AM
Nice to see some team building on the forum. I know, some of us are allergic to letter fungus, but I put together a neat top 10 list I wanted to share. Hey, feel free to modify it. But this one I always find fun to do. Except step 10 gets to be a bit of work. But, at any rate, here goes. So, as another member mentioned glowing white dot after the set is turned off is a good sign that you have (some) emission and (some) high voltage. Here's a few tricks I learned years ago.

1) Examine the neck of the CRT. If the Cathode and G1 are crooked at a noticable angle about 30 deg then you probably need an ION trap.

2) Turn off all lights in the room (do this at night) and let you eyes get used to the dark for about 15 minutes.

3) Turn on the set and let it warm up for a few minutes then turn it off to get the white dot.

4) If an ION trap is needed you need to figure out the best position and what impact it may have on brightness. Need to experiment a bit.

5) With your eyes acquainted to the dark the white dot will appear brighter to you. Slip the ION trap over the CRT socket onto the end of the tube and gradually slide it up the tube. Rotate slowly as you slide. Constantly watch how the brightness of the dot varies.

6) There should be a point where the maximum dot brightness appears on the screen. Leave the ION trap in this position.

7) Turn the set back on. Turn the brightness control OFF. Turn contrast to MID position. Tune in a station, hoepfully you'll get sound. If you can tune in a station then great! But if you can't ..don;t fuss. Just you blank raster for the next step.

8) Slowly increase the brightness and observe the screen carefully for raster. Inter play contrast and brightness controls. Most situations boil down to 2 conditions usually: a) weak HV and b) low emission. If HV is weak then setting the birghtness too high causes the HV to reduce (can't supply enough current) and the picture blooms until you can't see it. In the low emission case, brightness or contrast may bias the tube off. Watch for tell-tale 'negative picture' as the brightness or contrast begins to push the CRT into saturation. In some case you can bias off the CRT if misadjusted.

9) If you still can't get anything then try checking CRT emission with a CRT checker. But a CRT tester may not tell the truth, especially with older ION trap tubes and weak emission. I know some ION trap tube that don't show any emission on my B&K yet still produce marginally weak, but watchable, pictures.

10) All else fails there may be a circuit issue that's causing the CRT to bias off when the set is operating. Roll up your sleeves and get out the 'ol scope probe and start hunting!

kbmuri
10-28-2006, 09:54 PM
After finishing up the Magnavox, then taking care of a load of non-TV-related "job jar" items, this morning I got the Capehart 325 back out for another go-round with it.

I made an "error-in-thinking" assumption in one circuit. When replacing (and repositioning) the power-supply electrolytics, I pulled a wire from the case of one of the multi-can capacitors, and when repositioning the cap a mile away, decided to just run the wire to an equivalent point elsewhere in the circuit. Turns out it wasn't equivalent. Brain fart. It led to a dead section of TV set in the 6AH6 Video Amp section (among others). I corrected it. Full raster. After some knob turning (agc, focus, vert lin), I have pretty good-looking snow. Good stopping point for the night.

I'm really strongly leery about saying this. I have no larceny in my heart and no ill will towards anybody. Just for the people who were technically interested in technical details about the technical facts of this TV. It's displaying a very nice raster, with no ion trap.

Just the fact. No ion trap. No hidden meaning nor insults. Really.

I'll prolly post one more pic of it all zipped back up and showing a football game or something, just for full closure, then I'll retire from here. It's a fun place sometimes, sometimes not, and I admit I don't fit in very well. Problem's with me, you guys all are great.

Enjoy,

- Kirk

kbmuri
10-29-2006, 10:00 PM
progress...

kbmuri
10-29-2006, 10:08 PM
... success.

Lousy picture is from the Ramsey transmitter (lighter/darker blocks of picture). Will run it with a VCR for final photos.

Bottom-right corner has a neck shadow. Seems like a physical problem with the yoke mounting (too far up? too far down?). Will experiment.

Horizontal-hold had to be turned all the way in to get sync. Maybe an out-of-tolerance resistor in this circuit.

Simple stuff left.

Tony V
10-29-2006, 11:00 PM
Fantastic! Nice to finally see a pic on your Capehart as i know you've put alot of work into it. Its funny how alot of us resolve a puzzling problem after taking a break away from it once in awhile. Sometimes it just takes a fresh take on things to spot the obvious. Thanks for the update!
-Tony

kbmuri
11-06-2006, 02:52 PM
Not 100% perfect, but I'm satisfied.