Zenith Color Set

[ChuckA]

What can you color set gurus tell me about my latest purchase.

A Zenith model 5030, chassis 29JC20, 21FBP22 CRT.

Fired it up today, has a bright picture, no color.


Thanks

Chuck

[Chad Hauris]

The 3.58 mhz oscillator is probably not running. The most common cause of this that I've seen is a bad 3.58 mhz. crystal.
Measure the negative grid voltage on the 3.58 oscillator tube (pentode section). It should be around 5 volts. If the oscillator is not running there will be no grid-leak bias, voltage will be zero on grid, also plate voltage will be low because of increased current draw. Make sure that the oscillator is running before investigating other problems.

[ChuckA]

Chad,

Thanks for the info. Do you have any idea what year this set is from?

Chuck

[Rob]

Chuck,

You could also check the settting of the color killer control and try rocking the H. Sync control within the lock range to align the burst gate which may not be opening.

We need pictures of your score!

Rob

[ChuckA]

Here's the picture:

Chuck

[ChuckA]

And the chassis, quite clean just a lot of dust when I opened it up.

[Rob]

Chuck,

That certainly looks to me like an early 60's Zenith and it is in beautiful shape too! It looks like it has a 21FBP22 in it. Is this true? Also what the.......am I seeing rectifier tubes for B+ supply next to the power xfmer? That would be a first, another idication of early.

Rob

[ChuckA]

Rob,

Yes it's a 21FB CRT, and a pair of 3DG4 rectifiers. One is bad it arcs every now and then, just haven't been able to find one yet.

Just have to decide if I want to restore it, sell it, or keep it. I really don't have the room, but I still keep buying.


Same auction I brought home an RCA 6T54, for $2 I couldn't leave it. I forgot to load up the base unit when I left, luckily the auctioneer is going to be in my area the end of June and will bring it with him saves me a 3 hour drive.

Chuck

[Charlie]

That's a really nice looking 29JC. I believe it is from 1961. If I am not mistaken, all the 60's Zenith color chassis after this one use selenium rectifiers in the low voltage power supply. Note how large that power transformer is! That baby must weigh a ton! This model also sports seperate bass and treble controls for the audio.

[rca2000]

I happen to own one of those 29jc20 zenith sets, in the exact same cabinet as yours. mine does work pretty well, although it needs a little attention in the vertical lineraty ckt(probably a cathode bypass cap), and the crt is a little weak, especially the red gun, but i do get a good picture ,and color. on it.

The chassis is the FIRST regular production color set from zenith, a1962 model. It is the ONLY set they made with tube lv rectifiers (the next years chassis the 27, and 26kc20, had SILICON rectifiers, as did all of them after that). You, and I have a real rare item there, I only ran across one other 29jc20, and that was in 1986, behind a car repair garage.(I DID strip the chassis out of it, and STILL have it, today)

By the way, when I got my set home, from its 500+ mile ride from s.c., I had no color, or video, just bright retrace lines. I found that reseating the video output tube, as well as several tubes in the color section, brought everything back. If you hauled yours far, you might want to check this.

[captainmoody]

Sometimes the tv doesn't even have to be moved for that problem!
Most of my sets have sat for years, And in that time corrosion had built up on the socket pins causing all sorts of problems.
I just use a little contact cleaner on them and then all is well for the next few years!
I have had very few problems with 3.58 crystals and maybe only replaced one or two in 25 years of repair. It's funny, In the past, I have hired techs that get out a ton of equipment and get into a big technical dialogue about why this isn't working and how the circuit could be designed better, ETC and still couldn't find something simple as a cracked solder connection, Dirty contacts or the like. I have found that after working on equipment for years most of the troubleshooting is just easy common sense stuff!
Other than the contact prob, You might check for a bad cap or tube.
The most enjoyment I had from tv repair was the people that I would meet on walk-ins and service calls (many are still my friends now) And making sure repairs were performed properly and in as quick a manner as possible.
Customer service was always my area I guess, Most techs hated to go up front and deal with customers, Especially the ones that were angry!

[ChuckA]

Jack,


Thanks for the info on the set. I did have to reseat most of the tubes to get anything on the screen when I first unloaded it. Most of the tube pins had a light corrosion also that I cleaned off.

I did have a little color when I first turned it on, but it gradually just went away. I think it will need some new caps, as I did see a few black beauties in there.

Do you happen to have any extra knobs for it? I would like to get the missing bass control knob.


Chuck

[Charlie]

Oops! Yes Jack, you are right... silicon rectifiers. I got my minerals mixed up. But, I still believe it is 1961. I have a Zenith service manual here dedicated solely to this model, and the print date in the manual shows August 14, 1961. I doubt they would have made a service manual before the set. I also have another manual that covers Zenith color receivers from 1962-1969, and the 29JC is not included in it.

Note the little girl with the dog on the front. I can remember that picture on the cover of the owners manual of the set we had when I was young. Funny, I never thought I'd see that curly haired kid again!

[rca2000]

Well, you are right, and you are wrong. I have the same manual. It was printed in 1961, but the set was a 1962 model. I know this .from a number of articles in old magazines ,such as pf reporter, radio-electronics, etc.

[Charlie]

My apologies, Jack. I stand corrected.