Zenith 19L25 Chassis ( Service Info )
 

I've been thinking that when I get done with my Admiral, I want to take a crack at recapping that Zenith television set. It's a 1953 model L1846R with the 19L25 chassis. There's a member here at VK that posted a long time back that he had some service manuals, including this one that he'd be scanning into PDF format but I haven't been able to get ahold of him. I was wondering if anyone might have a copy somewhere I could get a look at because I haven't found any on the web and I can't exactly afford to order a set right now...

Update: I did find that I can get the schematic from Sam's with a subscription. Might be worth looking into, since I may be working on more things like this over time.

I also found out what type of CRT I've got here. It's a 17LP4. I'd like to remove it from the chassis because it weighs the thing down horrendously and I don't think I'm gonna be able to do much work on it until I do. There's a bunch of wires running to terminals which then run to the yoke which is held within a metal bracket. It's held down with about 4 screws, but it looks like I'm supposed to desolder the wires to free everything up.

Don't ask me why I included a picture of the 1B3GT. I thought it was purty.

Why would you want to un-solder the yoke?... on most of these old sets,one can slide the CRT out and leave the yoke mounted on the chassis. Am I missing something here?:scratch2:
jr

Ohhh yeah... so all I should really worry about is taking off is those magnet rings in the back and that ion trap and slide it out from the front?

Wow, I just got it out in no time. That was a lot more simple than it looked... thanks!

Do you have service info yet? I just picked up a stack of Rider's manuals today, and the complete service info on your set is here...

FWIW, I have a 10" tube with even bigger cracks on the neck. I put it into my dad's tv and he has been playing it nonstop for the last month or so-still runs good. I would at least use the old crt to set up your tv during restoration. Maybe hunt down a brightener if the picture is still dim after a recap...

Yeah, I'm pretty sure this CRT will do well-enough for me to check for improvement after I replace the capacitors. If there's hope for it, even with the cracks, then I might not count it out just yet. It had a dim picture that whole time and when I saw the crack around the neck, I'd feared the worst.

Oh, and I haven't gotten ANY kind of service info, yet! The whole reason I was taking out my CRT today was to get into the chassis and make a lame attempt to find the values on the capacitors themselves. The cap's don't look melted like the one's in my radios, but all the same. But yeah, if you were able to get that service information to me somehow or another, I would definitely appreciate it!

Sounds good. Pm me your shipping info and I'll get a copy made for you. If it is a slow day at work tomorrow, I might get the chance to go over the parts list and be able to tell you what caps would need to leave that set.

While I'm getting things sorted out, I thought I'd take a moment and talk about another interesting feature of my Zenith. It's probably not that uncommon for televisions of this vintage, but it's just something I had never seen before!

http://img831.imageshack.us/img831/4797/channelknob.jpg

This never actually worked the few times that I did turn on my tv, but got the idea of how this worked using a LED light on my keychain. To make it project the numerals properly, I'll have to do some adjusting. It had a type 47 bulb in there, which seems to work when I power it with a 9-volt battery. I never saw it light while in the television, however.

I wonder why it displays the number "25" when turned to channel "13" ...

http://www.videokarma.org/attachment...3&d=1279406118

I could be wrong on this particular TV set, but usually there's a plastic cap of sorts that would cover the terminals on the yoke, and also hold the centering magnetic rings. But the plastic used does decay, so it's not surprising that it's missing here. And the ion trap is way too far back on the neck.

You're right-the back cap of the yoke has rotted away, but luckily the centering rings are still there-rattling loose around the ion trap. I don't know what the "25" numeral is about-does this set have a UHF function?

Also your tube has a really neat label on it-what does it say?

I'm sure my set probably has UHF in there somewhere. It has a lot of interesting attachment plugs for various things such as a remote control of some sort, and also "Phonevision" which was the world's first pay-per-view system, exclusively from Zenith:

http://en.wikipedia.org/wiki/Phonevision

A great deal of that black plastic stuff has deteriorated throughout my set, especially around the yoke there and also around the back of the picture mask which resulted in little annoying crumbs of plastic falling between the face of the CRT and the glass. There were shards of black plastic everywhere in that set when I first got it, along with flakes of aquadag that fell off the CRT.

I had the ion trap moved back in an effort to fill out the picture which was leaving the bottom quarter of the screen black, which did help but I gave up knowing full well there was more to it than that. I'd like to figure out something I can put over the back of the yoke in place of that plastic stuff. I wouldn't mind getting that stuff out of there completely, especially around the picture mask.

Anyways, here's a look at the labels around my old CRT:

http://img842.imageshack.us/img842/6971/img0912.jpg

http://img832.imageshack.us/img832/9242/img0915.jpg

http://img837.imageshack.us/img837/1240/img0916.jpg

http://img842.imageshack.us/img842/177/img0914p.jpg

Oh... and check out these rather colorful plastic pieces that support the CRT:

http://img832.imageshack.us/img832/2298/img0918p.jpg

When I first took this thing apart, I seriously thought those looked like they were made out of marble or something...

Your ion trap is probably pushed back like that because your centering rings are screwing things up. They should be pushed flush up against the back of the yoke. Doing so and adjusting the ion trap for max brightness might give you a much better picture.

When I had this all together and I tried to get a picture on it, I recall that I had the centering rings all the way forward and I still could not get a good picture. I moved the ion trap back just a hair and found that it filled out the screen like I wanted, although I still had a small black spot in the top right and left corners. Before I did that, the image would even overlap itself at the bottom, and in general was slanted to the right. Everything was just streaming from right to left, completely unwatchable. The closest I ever came was when I had a John Wayne movie playing on the VCR and I could make out the characters in the movie, but they were scrolling up and down and sliding off into infinity towards the top right corner of the screen. No adjustment on the front panel improved this, so I gave up before I ran the set too long and fried something.

Greetings from FixitLand!

Now THAT is interesting! First thing I noticed in your picture is that the channel numbers aren't in numeric order; the same thing is done on my Zenith (K1846R "Stafford", chassis 19K20) which appears to be the previous year version of yours. But that ghost-like number is truly strange. Don't think my set has that feature. But it could be that your set, like mine, has a UHF "strip" in the tuner. On my set, it was installed in place of Channel 3 (so I don't have Channel 3 available!). Perhaps such a thing was done to your set? Very curious! I've gotta check my set a little closer...

Take care,
--
J. E. Knox 'The Victor Freak'

odd. It looks like another number off to the left? I wonder if it's just set for 25 on 13 or if it is the whole uhf band that displays thru the center. If so there must be some way of rotating the uhf display.

What does the rest of the tuner look like?

Phil

After looking through the service info that leadlike kindly put together for me, I'm pretty sure there's no UHF on my Zenith. It looks like there's supposed to be a separate tuner assembly mounted in front of the regular one which I obviously don't have in my tv. The knob itself should have UHF channel numbers listed around the outer circumference of the knob, which I don't have either.

Here's what the whole thing looked like the first time I removed it from it's cabinet.

http://www.videokarma.org/attachment...8&d=1272600439

Oh, and that other number was bleeding over in the picture because I was holding an LED to light it just for that photo. Properly mounted in the tv, it shouldn't show but one channel number at a time. 13 is the only instance where it projects a number other than what is shown on the gold bezel, in this case 25.

Greetings from FixitLand!

Boy, that sure makes me believe you've got a Channel 25 UHF strip in the VHF tuner's Channel 13 slot. My set's channel knob shows only the VHF channels as well (but doesn't have that "projection" feature). Since you've got the chassis out, it should be quite easy to pop the tuner's cover off and check the turret. There would be two strips, one slightly longer than the other. All the strips are marked with their channel number.

Take care,
--
J. E. Knox 'The Victor Freak'

My tuner seems to lift straight out the top as a whole unit, but sure enough, I did find this:

http://img69.imageshack.us/img69/4726/img0924z.jpg

So what's the functionality of having the one UHF channel?

Probably the town where it was originally sold only had channel 25. UHF channels were scarce in the early days, and it's possible to construct a tuner that receives both VHF and UHF if the right strips are inserted. This article has a description of a 1953 VHF-UHF tuner. It also includes a journal article that describes the tuner in more detail.

http://antiqueradio.org/RCACT-100TelevisionDesign.htm

Phil Nelson

Pictures
 

I know how you guys like pictures as much as I do, so I thought I'd give this old thread a bump and put up a few of what this '53 Zenith L1846R actually looks like:

http://img534.imageshack.us/img534/5631/dscf0871g.jpg

This is one of the first pictures I actually took of it, the day I brought it home. Cosmetically, it's in great condition and the only thing I'd really like to improve upon is the simulated "gold-plating" that's worn off on the control panel, particularly on the pencil box door.

http://img838.imageshack.us/img838/1888/dscf0875.jpg

Here's a good view of everything that's going on underneath the chassis. From what I've seen, everything there is probably original which calls for a complete recap. If you spot anything here that I should pay special attention to, do let me know! I hope to get to recapping this in the near future. It's a real pain to take this chassis out, mainly due to it's weight. Removing the CRT helps, but not as much as I'd like.

http://img193.imageshack.us/img193/7034/dscf0876z.jpg

This picture came out rather blurry, but I recall thinking it was one of the weirdest looking things I've ever seen inside of an electronic device. Based on what I know now, I believe this is the flyback transformer. I suppose if it were bad, I wouldn't have gotten a horizontal raster... and if it goes bad in the way that most transformers seem to do, I take it that it would get very hot, the wax would melt, and bad things would happen!

When did they invent gray, glittery wax? :scratch2:

I have a Zenith with similar chassis. Notice that some of the terminal strip lugs were left blank at the factory. I found that to be very considerate of them when I got around to replacing the old electrolytics.

And yes, that's your flyback, presumably a healthy one.

Oh, I didn't think about that, but it'll definitely be handy having those extra lugs. I have to admit, when I saw this circuitry for the first time, it was pretty intimidating. But, based on what I've worked on so far, I seem to work pretty slow and double-check everything as I go. It took me all day the first time I recapped a radio chassis, so I'd imagine it'll take me a few long nights to do this one.

I'm going to have to get a rebuilt CRT sent to me for this television, so the flyback had sure better hold up!

The coating on my fly was falling off so I coated it with non-acidic silicone. I bought it at the auto parts store (sensor safe). For the simulated gold you could try mohawk laquer. They have a clear with an amber tone that might work.

http://img838.imageshack.us/img838/1888/dscf0875.jpg
Lots of wax paper caps to replace, that will keep you off the streets for a while. Bumble bees and ceramic tube ones there.
http://www.wa2ise.com/radios/wax.gif

Ah, so is re-coating the flyback with silicone something I should look into doing to preserve it, or should I only worry if it's falling apart?

I haven't heard of the mohawk lacquer, so I'll have to look into that. I could just paint it, but I kinda wanted something semi-transparent or at least a bit more gold-looking than the typical metallic gold paint.

Hey, what do you guys usually do about power cords? I know it's easy to replace, but I wanted to make sure I got the right kind because it hooks to the tv with a 2-prong female end plug that fits into a riveted box on the back of the tv. It's actually loose unless it's pushed up onto the male prongs inside the tv. It's a pretty flimsy interlock if you ask me. What I mean, is usually on my radios, the power cord goes into a box which is securely mounted into the back of the radio and it's two ends go securely over the prongs sticking out the back of the chassis. This TV has the plug just loose inside a box, where yes, it doesn't come out of the box because of the big ears on the plug, but it has to be guided to fit tight fit onto the prongs from the chassis. I never really liked the way that felt when I put it together, so I'd be fine without the interlock, just having the proper plug by itself without being trapped in the back of the tv, and that would help me with testing also. Where should I look to get a cord like this? I've seen old-style cords but they have no pronged ends, so I figured I might have to reuse the old one and botch it together, but...? That doesn't seem right at all.