Museum of the Game® & International Arcade Museum® Forums
This was in a different thread, but someone suggested that if I WAS going to post it, to do so in a different thread.
I'll break the topic into several parts. I'll cover the intro and Zenith model numbers here. I'll cover the socket and the issue of removing the socket from the neckboard in another post (there's a very important detail). I'll show Dez's replacement neckboard (bare and after I populated it) in another post. And I'll cover 'details' in a final post, which covers things like ear mounting hole annoyances. Please be patient; I may need to go out and take new pictures, etc., so I may make a new post and wait a day before I've accumulated enough for the next post, and so on.
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What's a CR-20 tube?
'CR##' is actually a convenience definition. B&K CRT testers/rejuvenators use a CR## nomenclature for defining different CRT neck sockets.
The technical definition for the socket is EIA B9-271.
They are neither plug-compatible nor "almost plug-compatible" with the sockets on a 6100 or G08.
I know that more manufacturers used this neck socket style other than Zenith; I have a Magnavox "CR-20" socket here as a result.
However, Zeniths are easier to classify than others.
The list below is a list of Zenith models whose schematics and BOMs I've checked and that list a 100 degree tube. I've broken them into CR-20 and CR-23 categories.
Before someone asks, no, I do not have a conclusive list of all Zeniths nor do I have every schematic for every Zenith. I have access to a few, I've paid for the SAMS pages for a handful of the models as well. If it isn't here, I don't have it. I'm not warrantying anything; consider this a courtesy. If there's a typo, please don't send me hate mail.
Zenith model numbers (for several decades) were in the form of one to two letters, the size of the tube (aka '19' for 19"), two digits for the model itself, and frequently revision number suffixes. They're usually on a white (or now beige) sticker on the back of the set.
Single Focus, 100 degree, 19", CR-23: [These are super convenient and require minimal work. They're also pretty rare.]
SB1965, SB1971, SB1977
SA1961, SA1963, SA1977, SA1971
SS1909
Dual Focus, 100 degree, 19", CR-20: [NOT PLUG COMPATIBLE with a 6100 or G08!]
M1938, S1920
S1983W, S1987, S1989
K1960, SK1961, SK1971
I believe I've always seen 19VJNP22 tubes in these, incidentally.
========
Visually, the common sense 'fake woodgrain' is a good metric for the sets I've seen (although it's frequently vinyl woodgrain on particle board on some of these units, not purely on plastic). Having lived through the 1970s, I can tell you that YES, that faux woodgrain was everywhere. [Just as the matte black was everywhere in the 1990s.]
I've also noticed that the pricier sets from the day tended to be more likely to have a 100 degree rather than 90 degree tube.
Where do you find them? I can't tell you that; I live near a large city, and the "pickings are slim". I'd suggest making friends with CRT recyclers in your region, and people who live in more rural areas seem to have more luck – as urban areas just plain have more people digging through what's out there.
I have bought a couple on eBay, but, honestly, that just made every 19" Zenith's price go up, as apparently these folks using 'pricing websites' that pick the highest price paid and tell people to sell at that price.
Shipping any TV is pricey, and I generally don't recommend it. [The way some people ship stuff is disturbing. It's not complicated to ship a CRT, even a bare tube, and have it arrive okay, even with UPS/FedEx people treating the boxes poorly. However, the 'average Joe' doesn't have the patience for more than about 7 minutes of packing.]
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If you do have one of these sets, you'll likely find that getting the tube out is a nightmare. The mid-80s units seem so much more unified than the late-70s units. The last unit I took apart had a physical structure that required an amazing amount of disassembly before I could even get to the tube, and although I started attempting to damage as little as possible, I quickly gave up and started cutting cables and tossing individual PCBs in piles. An early 90s (non-Zenith, just a TV) proved to be more taking the back off, sliding the main PCBs off the neck, out of the rails, and unbolting the tube from the front façade. 10-15 minutes, max. One of these Zeniths took me at least 2 hours to extract the tube and I had a lot of PCB-waste afterward.
I can only suggest that you be strategic, make sure the tube is discharged before you cut anything, be especially careful with the neckboard, and be patient.
For reference, here's a picture of one of the neckboards. I don't recall if this was from a Zenith or a Magnavox, but the socket is essentially the same. [And note that it goes on the opposite side of the neckboard PCB than you're used to. I'll show a picture in the next post that shows one plugged in.]
[I'll add the next part likely tonight or tomorrow.]
I'll break the topic into several parts. I'll cover the intro and Zenith model numbers here. I'll cover the socket and the issue of removing the socket from the neckboard in another post (there's a very important detail). I'll show Dez's replacement neckboard (bare and after I populated it) in another post. And I'll cover 'details' in a final post, which covers things like ear mounting hole annoyances. Please be patient; I may need to go out and take new pictures, etc., so I may make a new post and wait a day before I've accumulated enough for the next post, and so on.
=======
What's a CR-20 tube?
'CR##' is actually a convenience definition. B&K CRT testers/rejuvenators use a CR## nomenclature for defining different CRT neck sockets.
The technical definition for the socket is EIA B9-271.
They are neither plug-compatible nor "almost plug-compatible" with the sockets on a 6100 or G08.
I know that more manufacturers used this neck socket style other than Zenith; I have a Magnavox "CR-20" socket here as a result.
However, Zeniths are easier to classify than others.
The list below is a list of Zenith models whose schematics and BOMs I've checked and that list a 100 degree tube. I've broken them into CR-20 and CR-23 categories.
Before someone asks, no, I do not have a conclusive list of all Zeniths nor do I have every schematic for every Zenith. I have access to a few, I've paid for the SAMS pages for a handful of the models as well. If it isn't here, I don't have it. I'm not warrantying anything; consider this a courtesy. If there's a typo, please don't send me hate mail.
Zenith model numbers (for several decades) were in the form of one to two letters, the size of the tube (aka '19' for 19"), two digits for the model itself, and frequently revision number suffixes. They're usually on a white (or now beige) sticker on the back of the set.
Single Focus, 100 degree, 19", CR-23: [These are super convenient and require minimal work. They're also pretty rare.]
SB1965, SB1971, SB1977
SA1961, SA1963, SA1977, SA1971
SS1909
Dual Focus, 100 degree, 19", CR-20: [NOT PLUG COMPATIBLE with a 6100 or G08!]
M1938, S1920
S1983W, S1987, S1989
K1960, SK1961, SK1971
I believe I've always seen 19VJNP22 tubes in these, incidentally.
========
Visually, the common sense 'fake woodgrain' is a good metric for the sets I've seen (although it's frequently vinyl woodgrain on particle board on some of these units, not purely on plastic). Having lived through the 1970s, I can tell you that YES, that faux woodgrain was everywhere. [Just as the matte black was everywhere in the 1990s.]
I've also noticed that the pricier sets from the day tended to be more likely to have a 100 degree rather than 90 degree tube.
Where do you find them? I can't tell you that; I live near a large city, and the "pickings are slim". I'd suggest making friends with CRT recyclers in your region, and people who live in more rural areas seem to have more luck – as urban areas just plain have more people digging through what's out there.
I have bought a couple on eBay, but, honestly, that just made every 19" Zenith's price go up, as apparently these folks using 'pricing websites' that pick the highest price paid and tell people to sell at that price.
Shipping any TV is pricey, and I generally don't recommend it. [The way some people ship stuff is disturbing. It's not complicated to ship a CRT, even a bare tube, and have it arrive okay, even with UPS/FedEx people treating the boxes poorly. However, the 'average Joe' doesn't have the patience for more than about 7 minutes of packing.]========
If you do have one of these sets, you'll likely find that getting the tube out is a nightmare. The mid-80s units seem so much more unified than the late-70s units. The last unit I took apart had a physical structure that required an amazing amount of disassembly before I could even get to the tube, and although I started attempting to damage as little as possible, I quickly gave up and started cutting cables and tossing individual PCBs in piles. An early 90s (non-Zenith, just a TV) proved to be more taking the back off, sliding the main PCBs off the neck, out of the rails, and unbolting the tube from the front façade. 10-15 minutes, max. One of these Zeniths took me at least 2 hours to extract the tube and I had a lot of PCB-waste afterward.
I can only suggest that you be strategic, make sure the tube is discharged before you cut anything, be especially careful with the neckboard, and be patient.
For reference, here's a picture of one of the neckboards. I don't recall if this was from a Zenith or a Magnavox, but the socket is essentially the same. [And note that it goes on the opposite side of the neckboard PCB than you're used to. I'll show a picture in the next post that shows one plugged in.]
[I'll add the next part likely tonight or tomorrow.]