Hey guys, look what the neighbors threw out :p:

It looks to be pretty late for a tube set, even has a couple Rat Shack lifetime replacement tubes. Haven't had time to check it electrically.

The top tuner is actually some sort of UHF with a fixed number of positions, the bottom is VHF and the channel indicators rotate vertically, fairly deep below the faceplate. Any idea on year of manu? It seems to be up to Zenith standards...

Cory

Looks like about 1972-74 or so.

1970. Its got a 14A12C52 chassis with that control layout.(im pretty sure) Nice looking set. Radio shanty "lifetimes" are ok if they are the gold plated pin types, however, the newer ones that you could buy up to about 3 years ago were used junk with lifetime printed on them. If you look at a newer tube and angle it in the light just right, you can see where the original name was that got erased. In fact, I got into a huge problem on ebay in which I sold a Grundig table radio with lifetime tubes in it. I think the guy had a heart attack when he took the back off as he was "horrified" when he saw those (quote from the complaint email). "you insulted this fine piece of equipment"

Just so you know, zenith followed a chassis date pattern, in which the first letter in the chassis represents the year of the chassis, like "20Y1C48", in which "Y" is 1968, so:

M 65
N 66
X 67
Y 68
Z 69
A 70
B 71
C 72
D 73
E 74

Let us know how it works, which im sure it does as its zenith quality. Nice Nice Find!!!!!!!!

Hmmm, I didn't see any 25V" models in the 1970 Zenith pamphlet,
only 23v" with that same control layout. Perhaps it is a 1971 model year built in 1970?

Well, I plugged it in (no antenna) and it pulled in the audio great. No luck getting any light on the CRT though. The filaments look good so I'm leaning towards HV. Anything in that section to watch for in these color sets? Dampers? Door knob caps?

Thanks,
Cory

I like to use a neon lamp to test for HV. Hold it near the horizontal output plate cap lead to see if there is HV AC there, it will glow. (just hold it near the insulation, no direct connection). If it passes this test, you can hold it very carefully near the HV rectifier plate cap to see if it glows. If there is no glow of the lamp at the Horiz. plate cap, measure the negative grid voltage at the horiz output tube. Should be around -40 to -50 volts. No negative grid voltage developed=no input signal from oscillator, or could mean output stage or damper is not operating. To help check these stages...

DISCONNECT the plate cap from the Horizontal output tube and connect the meter to the plate cap wire, not the tube (make sure it is disconnected). Then, measure the DC voltage, if you get the B+ voltage, you know it is flowing through the damper and flyback. The B+ input comes in to the horizontal output/damper system through the damper. Check if there are any fuses out in the HO tube cathode or the damper plate.

Is this the four tube model with the tripler or is it the full-tube model?

The door knob caps are generally only used in the metal tube sets where the CRT cannot provide its own filter capacitance between the inner and outer graphite coatings.

Cory,

Wow! You must be fairly close to your local TV stations if you are getting sound without an antenna on that set. Most TVs require some sort of antenna to get anything, unless they are extremely close to the transmitters. (I don't know where in Iowa you are, but I live in a fringe area 45 miles from the nearest stations and don't get much of anything on my TVs without cable.)

As to the picture problem (no light on the face of the CRT), I'd check the horizontal oscillator, output and HV rectifier first, before anything else. There could be other problems with the HV filter capacitors, flyback, etc. but since 80 percent of all troubles in tube-powered television sets are caused by weak or dead tubes, I would check the tubes first.

Beware of the high voltage on the CRT, which in color sets can run 25 kilovolts or more for a large-screen tube such as your set has. Remember to discharge the HV filter capacitors in the HV cage (and the coating on the bell of the tube, which in modern sets is the HV filter capacitor--the doorknob types went out with metal-cone CRTs like 16GP4s and the like). If you don't, you can get a nasty shock from the discharge.

Do not work on the set with the power on and the plug still in the wall socket. I know that sounds elementary, but many people have been injured or killed working on TVs that were still plugged in and :eek: turned on.


BTW, I have never had bad luck with Radio Shack tubes. I used them quite a bit when I was working on old sets in the '70s; the tubes all worked well. These were the ones with the gold-plated pins, though. I read in another post that RS resorted to rebranding used tubes long about 1999 or 2000. I agree with that poster--these relabeled tubes are junk. Who knows how good or bad a used tube is? Caveat emptor (let the buyer beware) applies when buying old or used tubes/components as much as it does to bidding on used electronics on ebay.

BTW (2): Once you get your set working as it should, you will have a TV you can be proud of. Zeniths of 1970s vintage and earlier were very good sets and were actually made by Zenith of Chicago, not like today's troublesome "Zeniths" coming out of Korea and manufactured by Gold Star. These sets are not made by Zenith, even though the Zenith name is on them. Zenith, for all intents and purposes, went out of the TV business when GS bought them out in the '90s. The Zenith name is now only a marketing label, as is the stylized RCA logo on sets now made by Thomson Electronics.

Zenith used to be my favorite brand of TV set, but since they moved overseas, I wouldn't own one today. I purchased my present RCA XL-100 19-incher new in 1999 and have had little trouble with it to date. Heaven forbid if that set would have been a Zenith. I have a Zenith Sentry 2 19" color set in my bedroom which is eight years old and still works well, however. Perhaps Zenith TVs were still being made halfway decently in the mid-90s; who knows? Or maybe my set was an exception to the rule? :dunno:





Good luck and very kind regards,