Zenith Roundie Ebay

[polaraman]

This one is in Lincoln, Nebraska. Could this be a 29JC20?

Polaraman

http://cgi.ebay.com/Zenith-Color-Con...QQcmdZViewItem

[jstout66]

I bid on it as I am in Omaha, but it must have a hefty reserve....

[Charlie]

Can't really see in the picture, but seems I remember one of the features of a 29JC was having seperate bass/treble controls at the top of the little control door. It also appears to have a UHF tuner... which would have been optional.

Sure is a clean looking set. Too bad there aren't a few more photos in the auction.

[smoker76]

That looks like a great set to get but I wonder if that CRT color is that of a rebuilt tube. I thought that Zenith would have had the CRT match the frame color.
Are those shopping cart wheels below it? Should that set have 6" legs with gold end caps?
I just read it comes with original legs! Luckily!

[polaraman]

My Zenith 29JC20 is VERY heavy! It was smart of them to put wheels on the TV. I have fabricated dollies under some of my heavier sets. I can now move them with out damaging the hardwood floors.


polaraman

[polaraman]

I believe that this set is the one recently placed on the ETF classifieds. They were asking $150 for the set.


polaraman

[jpdylon]

that is not a bad price if the tube is good and the chassis is in working order. I wish it weren't so far from me.

[jstout66]

I got this set today. The owner had it on on Craigslist. Since it was in Lincoln, NE. and I am in Omaha, I bought it and he delivered! The chassis is 24MC32 and it does have a rebuilt tube, a really ODD brand. (alpha industries,INC) The owner included the legs which "twisted" right on. Set's in good shape and came from the original owner, however it is not without quirks. The focus isn't the best, the sound isn't very loud, and I have a slight vertical "jump". 1st question, what would cause weak sound, and 2nd, where the hell is the vertical size and lin controls on this set? They are not behind the control door, and I can't find them on the chassis. I hope I can get this working better. It had a few bad tubes, which I will order tomorrow. For sound output the set calls for a 6J10 and it has a 6Z10 instead. Would that make a difference or are they the same tube?

[jpdylon]

sound: check the Buzz control on the rear of the chassis. i believe this was part of the discriminator so it may clear up the sound. The 6j10 has the same base as the 6z10, but electrically the 6j10 is the better of the two. Try subbing it out.

I'm surprised the vertical controls are no on the rear of the chassis where the screen and driver controls are. Are you sure there are no holes inside the control door where the rest of the controls are? sometimes there would be screw driver adjustments next to the pull-out controls. It would also be where the static convergence is hidden. See if there is a 1/4" head inside the control door. Some zeniths had these to remove the speaker, which the convergence controls and the like were hidden behind.

[jstout66]

I will order the 6J10 as I hate using subbed tubes. I found the controls for vertical. They WERE behind the control door, but unmarked. this is a beautiful set, but I hope I can get the picture better. My RCA CTC16 has a better picture than this set, but I'll see after I get the bad tubes changed. I have to get a 6J10, a 6KT8, 6JC6, 6BZ6, and a 12GN7. Convergency and purity have to be touched up as well. The owner told me there was an old shop in Lincoln, NE. that still serviced this set. I see the flyback has been changed as well.

[Bill R]

The vert size and vert lin controls are located behind the control door. They should be accessable with a small scredriver through a hole. The vert size is located below the color level and the vert lin is below and to the right. Look for two small access holes.

Bill R.

Sams 804-4 by the way.

[jstout66]

Well.... it wasn't a simple tube change for this one. I got all the bad tubes replaced and I still have lousy sound and that slight vertical "jitter" Does anyone have any idea what I need to look for? The sound is really annoying. It's got 2 huge speakers in the set and there isn't alot of sound output. I tried the buzz control and it didn't help. Also, would the slight vertical "jitter" be a cap. I'm not with it, when it comes to delving into this area, and I'm not familiar with Zenith chassis at all

[polaraman]

I have a service manual for my Zenith 29JC20. I do not know if this will work in your set.

Couple of things from the 29JC20 service manual.

1. The beat between the two IF carriers (sound and video) is detected by crystal diode X2 resulting in 4.5 megacycle signal being amplified through 1/2 the 6AU8 (I do not know what tube your set uses) tube providing adequate sound level for sound take-off. The video signal is also taken from this amplifier and coupled to the sync clipper for sync separation.

2. Proper alignment of the 4.5MC intercarrier sound channel can be made using transmitted Tv station signal. However, the signal to the receiver antenna terminals must be maintained at a reduced level BELOW the limiting point of the 6BN6 Sound discriminator. This lever can easily be identified by the hiss which often accompanies the sound. various methods may be used to reduce Tv signal level; however, a step attenuator is recommended for most satisfactory results.

1. Connect the step attenuator between the antenna and the
receiver antenna terminals.

2. Tune in a Tv signal. Adjust the step attenuator until a signal
is reduced to a low level where a HISS is heard in the sound.

3. Alternately adjust T5, T7, L23 and R52 (BUZZ ADJUSTMENT) for
the best quality sound for minimum buzz.

NOTE: Any one of these adjustments my cause the hiss to disappear, necessitating a further reduction of the Tv signal. The HISS must be present for accurate sound alignment.

I would check the BUZZ Adjustment if there is one. Also check the Limiter or sound discriminator stages.

3. It says in another test to adjust the volume to near maximum. Pull the sound output tube and reinserting it into its socket while listining for a slight "click". If a click is heard, it can be assumed that the speaker and audio putput are operating normally.

Do the same for the Sound Discriminator and the sound limiter tubes. If a click is not heard then that is the bad stage.

polaraman

[drh4683]

It shouldnt make any difference what sound tube you put in there. Most tubes end up being marked as both the 6J10/6Z10. Your sound problem is most likely and out of adjustment quadrature coil. Ive run into this a few times. the quad coil on your chassis is DIRECTLY to the right of the 6J10, its a coil mounted close to the chassis. The other two coils to adjust are the intercarrier coil (First coil directly to the left of the 6J10) and the sound take off, which is to the left of the intercarrier coil. Both of these coils are in the aluminum cans. And the buzz control of course. Those are your 4 adjustments that will affect your sound and output quality.
Yes, it is best to tune to a weak station and attenuate the signal. If you dont have the attenuator then just short the two screw jacks together with an incomming signal and try to tune in the worst hard to receive station. For me its CBS 2. In fact, I dont even need an attenuator if I adjust to that station . In order to make this adjustment as best as possible, you want to hear the "hiss" in the background of the sound. What you want to do is alternately adjust all 4 of these controls untill you have acheived the best possible clearest and loudest sound. Most likely though, adjusting the quad coil and the buzz control alternatly should do it, however, if someone was in there tinkering, then you will want to adjust the other two. Obviously make sure you mark your adjustment tool so you know how many times you've turned a coil. This should do it. Ive had a number of sets in the past, and one of them was a 24MC32 with bad sound. In my case, I just turned the quad coil and the sound exploaded with power. Its not uncommon to need to "touch up" the quad coil in a zenith set.
As for your jittering vertical, you probably have a dirty set up switch. Time and time again Ive had jittering vertical, all caused by a dirty set up switch. Just switch it back and fourth a few times should stop that trouble. It will probably come back though. Your best bet is to shoot some tuner cleaner in that switch and work the switch a few times.

These have always been the cases for me with troubles like you describe. Hopefully its nothing different for you. Good luck.

[vintagecollect]

Hello DRH,
Can you give me a buzz please at your convenience, my PC is down.