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  #271  
Old 06-25-2009, 04:28 AM
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The Zenith model 5315 (chassis 24MC32) from the New York score proved to be in the worst shape of the three. It's in a badly-scratched cabinet with a faux finish which will be quite difficult to save. Something had obviously clobbered the back cover, also, as is fairly obvious from breaks in the Masonite and a large hole in the neck shield. I glued what was left of the shield back together with epoxy to protect the usable 21FBP22 inside while the set is in storage. That set will be put aside pending my decision to attempt saving the cabinet. For now, its p/n 95-2263 Chroma Injection transformer was transplanted into my Zenith model 5415 (also a 24MC32 chassis) shown here, since the original Chroma transformer was broken beyond repair before I acquired the set. This set's cabinet is in much better condition.

This set holds special significance for me, in the form of childhood memories. As I've posted here before, my grandparents owned several Zenith "roundie" sets years ago. Somewhere in photo albums at my parents' house are some photos of me at about my grandson's age, taken at my grandparents' house with one of their Zenith "roundie" sets clearly visible in the background. Next time my grandson visits, I'm sure there will be a snapshot taken of him either by me or my parents where this set will be in the background. Family tradition? As some already know, "Lost in Space" is my all-time favorite TV series. Since the first time I had seen one of the 54 color episodes of "Lost in Space" on a color set was at my grandparents' house on their Zenith roundie, my choice of DVD's to play for these pics was obvious. This was the third-season episode where the Robinsons finally return to Earth, only to discover that their having exceeded the speed of light has carried them back in time to 1947, to a small town in Michigan where no one has even seen a television yet except in a Popular Mechanics article.

One of my favorite features of this and similar Zenith sets is the "rear projection channel dial" where the dial lamp projects the image of the selected channel number into the indicator window at the center of the knob.
Attached Images
File Type: jpg Zenith 24MC32 004s.jpg (24.9 KB, 94 views)
File Type: jpg Zenith 24MC32 006s.jpg (24.8 KB, 83 views)
File Type: jpg Zenith 24MC32 014s.jpg (33.2 KB, 125 views)
File Type: jpg Zenith 24MC32 022s.jpg (25.8 KB, 77 views)

Last edited by jshorva65; 06-25-2009 at 04:39 AM.
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  #272  
Old 06-25-2009, 08:11 AM
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Here are the promised pics of the NY Road Trip scores. In addition to the cracked back cover and broken neckguard, the model 5315 (24MC32) is also missing its metal service-access cover from the bottom of its cabinet. The 27KC20 and 25LC30 sets I scored have their cover plates, however, and it appears that all of the "roundie" models from the "K-series" to at least the "M-series" used identical access panels. If I decide to restore this model 5315 despite its rough cabinet, I'll just have my local metal fabrication consultant make a repro from one of the other sets' bottom plates. Scoring a replacement neckguard or having a repro made will be substantially more difficult, since I'm not aware of any plastics companies where it can be done economically (without an outrageously high minimum quantity and/or mold-making fee). The legs of all three sets are present, but stored in a box temporarily. The VHF knob for the 5315 is also present, but on the bench waiting for epoxy to dry after repair of its cracked knob skirt. All three sets are blessed with good CRT's (21FBP22's, thus immune from cataracts). The 25LC30 has a genuine wood veneer finish, so it can be refinished in the usual manner. The 27KC20 and 24MC32 are another story, as the faux finish will be next to impossible to save. About the only way is to refinish the moldings, cut replacement panels from 1/8" cabinet-grade plywood, and finish the panels to match. Here are the two CRT's also. I'll be double-boxing the used 21GVP22 and its support box in a replacement outer box, since the outer box we used to protect it on the trip home sustained some rain damage when the tarps shifted and that box had to be trashed when we unloaded the truck. It's packed with large styrofoam blocks supporting the bell of the tube inside the Zenith TV box. A suitable outer box and cardboard/foam inserts will be used to protect the neck as we did on the trip home.

Now, all I need to score are a 29JC20 and a 25NC33 to have an all-series'-represented Zenith roundie collection (featuring at least one model from each "roundie" series from "J-series" to "N-series"). Getting there! I'm sure Doug must already have reached that milestone with his collection. I think he has the largest collection of Zenith roundie sets of anyone I've met, unless someone else from the Conventions has a larger collection.

I also have a delaminated 21FJP22 (not pictured here) that I planned to install in the Sylvania 31C304M. I'll still be installing that tube in the Sylvania set, but not for my personal collection. It seems Todd regrets trading his 31C606MU after all, and will be arranging a trade for my delaminated 21FJP22 since it is now identical to a 21FBP22. I'll probably also be recapping that set for him, since he hasn't recapped a color set yet. We'll probably arrange for this to be a teaching opportunity, since he's eager to build upon his experience with radios toward becoming proficient with the more-advanced techniques required for TV and the ultra-advanced demands of color set restoration.
Attached Images
File Type: jpg Road Trip Scores 001s.jpg (29.2 KB, 80 views)
File Type: jpg Road Trip Scores 004s.jpg (32.0 KB, 96 views)
File Type: jpg Road Trip Scores 005s.jpg (32.3 KB, 69 views)
File Type: jpg Road Trip Scores 006s.jpg (31.1 KB, 74 views)
File Type: jpg Road Trip Scores 007s.jpg (32.0 KB, 46 views)

Last edited by jshorva65; 07-02-2009 at 11:13 AM.
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  #273  
Old 07-02-2009, 08:44 AM
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Wow, I think that 5315 is the same model I have. I know for sure the chassis is 24MC32. In fact, I think it might even have been yours at one time!

veg
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File Type: jpg zenithsmall.jpg (15.3 KB, 65 views)
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  #274  
Old 07-05-2009, 07:51 AM
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It seems that my "road trip" scores, in addition to the rare 27KC20, also included a rarely-seen version of the 25LC30. In addition to the genuine wood veneer on its cabinet, the example I scored features an unexpected production variation in its chassis layout. Normally, as shown in the Sams folder for this model/chassis (#722-4), a two-section 80uF/475V+160uF/250V is employed, with its sections arranged as the +410V Filter and lower half of the Doubler respectively. In my example, model 5119 coded 66B26, two separate single-section cans are used with appropriate cutouts provided on the chassis and clearly as a factory-original variation. This discovery was made during setup for routine reforming and performance testing of the set's existing electrolytic capacitor complement.

Incidentally, is anyone familiar with the significance of the five-character codes printed in black ink on the rear covers of these sets and typically consisting of a two-digit number, a letter, and another two-digit number? As stated, this set is coded 66B26. My 5315/24MC32 is coded 67B08, my 5415/24MC32 bears the code 65D12. No code was found on the rear cover of the 5025/27KC20. Until encountering the code on the 5119 which does not fit my initial hypothesis, I had presumed these codes to identify the week of manufacture (65D12 as 4th week of December, 1965; 67B08 as second week of August, 1967). Not only does 66B26 not fit this pattern, but a manufacture date in 1966 for a VHF-only set does not appear to comply with the "All-Channel" requirement which became effective as of April, 1964. Since the set was purchased near the Canadian border, however, it might be possible for the set to have been produced for sale in Canada and thus exempt from rules which were applied only to sets which were to be distributed to American vendors. Such was the case with certain G.E. PortaColor sets manufactured for Canadian markets and only equipped with VHF tuners.
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  #275  
Old 07-05-2009, 08:52 AM
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This is in a interesting observation. I'm going to look at various zenith sets of mine and see if I can come up with some kind of logical pattern for that sequence.
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  #276  
Old 07-05-2009, 10:37 AM
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The code might also indicate Year/Day/Week such as 66B26 indicating Tuesday of the 26th work week in 1966, again presuming this set was to be shipped to a Canadian dealer, due to the "All Channel" restriction effective April, 1964 for U.S. markets. That explanation also conflicts with the presence of a Service decal bearing the name of a shop with a New York address, however, unless the set was subsequently resold as a "used" item to an American household by its original Canadian owner and eventually serviced at the shop in New York whose label was affixed to the back.

Incidentally, I'm still searching for a Zenith roundie model equipped with Space Command. So far, the only remote-equipped "vintage" set I've ever personally owned was an RCA from the XL-100 era, a CTC-68 chassis, as I remember, that I bought used in the late 80s with its transistorized ultrasonic remote transmitter.
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  #277  
Old 07-05-2009, 11:01 AM
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After checking a few sets, I believe its purly coincidental that the numbers appear close to the approximate assembly year of the TV. I checked a '66 Zenith roundie I have, the back was written "Purchased 9-1-66" and the code reads 68G16.

I have a '69 Zenith, the code is 16A14, its a metal cabinet color set, the date stamp inside the set indicates 1-7-69 and the back of the set was written "Installed 1-25-69", incidently that set was hot off the line when it was bought!

As of now, the best way to determine assembly is by original tubes, or if you're lucky, sometimes they have the actual date stamp on the inside of the cabinet. Another way is the filter cans sometimes have date codes as does the 3.58 crystal. Later zeniths have the actual month and day date printed on the delay line.
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  #278  
Old 07-05-2009, 03:53 PM
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Quote:
Originally Posted by drh4683 View Post
Another way is the filter cans sometimes have date codes as does the 3.58 crystal. Later zeniths have the actual month and day date printed on the delay line.
My CTC-59 has the date on the delay line as well. The RCAs have the model year on the tag, but that doesn't say anything about the actual build date.

-Jim
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  #279  
Old 07-06-2009, 02:12 AM
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Another question specific to "roundie" Zenith sets, since I have only seen this set of typically-vacant antenna terminal locations on the backs of Zenith sets from the "roundie" era ...

Many mid-1960s Zenith sets (especially "roundie" Color models) had terminal positions marked VHF, UHF Strips, and UHF Tuner on their terminal boards. Those having UHF tuners always had their UHF terminals inserted into the UHF Tuner positions. Both UHF terminal pairs were left vacant on VHF-only sets. My best guess is that the UHF Strips terminal locations were for use with specially-equipped Space Command sets to allow removal of unused VHF channel segments from the set's tuner turret by a service facility in order to substitute a segment designed to pick up a specific UHF channel or to be preset to a channel within a predefined range like a "pushbutton" car radio, allowing remote access to "favorite" UHF channels without the added complexity of a separate remote tuning function (with the necessary separate relay and drive motor) which a standard UHF tuner would have required. Perhaps channel strips for each of the 70 UHF channels were sold as accessories, or limited-range strips (channels 20-30, 30-40, etc.) were sold to be preset by the service shop to a channel in that range, along with a set of channel number tabs to be installed in the appropriate postion(s) on the knob. A remote set purchased in the Youngstown, OH area might have had its standard 2,3,4, ... 13, UHF, 2 ... sequence modified to provide "instant preset" tuning via remote of 12 active channels in that market (3, 5, 8, 21, 23, 25, 27, 33, 35, 43, 45, 61) or had one or more VHF stations from the Pittsburgh market (2, 4. 9, or 11) substituted if the set's owner rarely or never watched PBS affiliates 25 and 45 and had an antenna capable of receiving Pittsburgh stations clearly from Youngstown. Such an installation might also have been equipped with a manually-operated UHF tuner if a large number of UHF stations were available, which would then receive the last channel manually tuned on its dial each time the remote-operated turret tuner was set to the UHF position.

Are there any Zenith experts here who can provide some insight, perhaps direct from a service manual or other OEM reference materials?

Last edited by jshorva65; 07-06-2009 at 02:15 AM.
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  #280  
Old 07-06-2009, 08:45 PM
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I think you're right-seems like there was a discussion about this before, I think on the ARF. I do have some dial inserts for ch. 16 which went with strips, for a Zenith. They seem to predate the sets in question, though. Somewhere in my "archives" the story must be written down...too much digging for now.
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  #281  
Old 07-07-2009, 07:58 AM
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It would be interesting to examine a photo of one of the UHF strips and/or a schematic. I would guess that the strips were most-likely designed as universal, tuning all UHF channels perhaps via Coarse and Fine adjustments. It would seem most practical for the Coarse adjustment to be accessible from the rear or concentric with and located behind the Fine adjustment similar to double-tuned IF coils. It seems exceptionally likely that the setup procedure would have involved the use of an alignment tool to set both adjustments such that optimal tuning of the desired channel occurred at the midpoint of the range of adjustment which would be permitted by the Fine Tuning linkage after the knobs were reinstalled.
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  #282  
Old 07-16-2009, 10:22 AM
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Zenith 25LC30 Roundie Progress

Here's the latest on the Zenith 25LC30 "Roundie" scored on the recent NY road trip. Cabinet finish is being restored as I write this. After cleaning up an absolutely filthy 3AT2 socket cup, some other cleanup work inside the HV cage, re-forming its electrolytics, and temporarily opening the 6HF5 cathode circuit for later fuse installation, the chassis was connected to the CK3000 Test Rig and put through a soft-start which it passed quite nicely. After the soft-start, the 300mA fuse was inserted into the 6HF5 cathode circuit. The chassis produced a recognizable picture almost immediately upon warmup, after just a few minor tweaks of the front-panel operating controls. Monitoring the 6HF5 cathode, the current reading was a very safe 202mA, within 1% of the 200mA specified by the Sams data. Sams specified an obviously-incorrect 26.5-27.5kV anode voltage range. The measured HV was within 1kV of the 23.5-24.5kV range typically specified for sets employing a 21FBP22 CRT, so the HV needed little adjustment to bring it within specifications. I've got some 0.015uF/1kV and 0.15uF/1kV capacitors on order to replace some "white time bomb" caps which seem to be OK for testing until the replacements arrive. There are fewer than a dozen capacitors on this chassis which will be replaced as preventive maintenance. The vast majority of capacitors in this chassis are of typically reliable epoxy-dipped construction (epoxy-dipped ceramic discs and Orange Drop equivalents). Here are the photos from the testing I've done so far. It appears that dripping wax from the FBT and HV arcing were used as an excuse for this set's having been taken out of service, probably condemned for a presumed "bad flyback" as a sales opportunity for a new "solid state" set of perhaps the Chromacolor II era. Some wax had dripped out of the FBT, but it was a very small quantity and it was very easy to pour some new wax into the small void which the dripping wax had formed. After a few hours of continuous bench testing, all electrolytics and the FBT have remained cool. Line current draw is 2.75A at 120V. Considering the crummy dynamic convergence capabilities typical of test rigs, the picture quality looks quite good.
Attached Images
File Type: jpg DSCN4238 (Medium).JPG (116.5 KB, 48 views)
File Type: jpg DSCN4242 (Medium).JPG (86.4 KB, 27 views)
File Type: jpg DSCN4249 (Medium).JPG (41.4 KB, 53 views)
File Type: jpg DSCN4258 (Medium).JPG (55.3 KB, 39 views)

Last edited by jshorva65; 07-16-2009 at 10:31 AM.
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  #283  
Old 07-16-2009, 07:09 PM
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Nice work John.
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  #284  
Old 07-16-2009, 10:36 PM
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Quote:
Originally Posted by jshorva65 View Post
...new "solid state" set of perhaps the Chromacolor II era. Some wax had dripped out of the FBT, but it was a very small quantity and it was very easy to pour some new wax into the small void which the dripping wax had formed...
What kind of wax do you use? Anything special?

John
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  #285  
Old 07-16-2009, 11:13 PM
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Quote:
Originally Posted by jeyurkon View Post
What kind of wax do you use? Anything special?

John
Nothing special, actually. This was near the core of the FBT, so it was not in close proximity to the HV windings. Wax salvaged from old transformers or even from old paper capacitors is adequate for the low-voltage areas. It's important to heat the wax for several minutes before pouring to drive as much water vapor out as possible. Continue heating the wax at a steady 212 degrees until steam is no longer visibly escaping the surface.

Last edited by jshorva65; 07-17-2009 at 10:25 AM.
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