1963 Zenith 29JC20 restoration

[NewVista]

The Zenith are prone to line pairing, I've found you can improve the interlace by fine tuning the Vert hold. They say increasing the integrator resistance also helps.

[Zenith6S321]

Originally Posted by NewVista

The Zenith are prone to line pairing, I've found you can improve the interlace by fine tuning the Vert hold. They say increasing the integrator resistance also helps.

Could you point out which resistor(s) using the attached Sams diagram? I have not replaced the K1 and K2 networks. I do see that the odd and even horizontal scan lines seem to be offset horizontally from each other when I look at the color bar pattern. If you zoom in on the color bar patter in post #35 you can just see the offset. Thanks.

Dave

[Zenith6S321]

I found a note in Goodman about the cause of the centering strings to not adjust the centering. The glue fails and the magnetic rings no longer move. I am going to try to re-glue mine.

[Zenith6S321]

Originally Posted by damen

Your 29JC is looking good. I have the manual scanned for it I could send you a link to if you don't have it. Just PM Me.

Wow, cool! PM sent.

Dave

[Zenith6S321]

I took my centering rings out and re-glued them. Here are some pictures. There is a plastic ring at the end of the centering strings. The plastic rings are glued to the magnetic rings. The glue on mine had failed. I used some epoxy to glue them back on. There is a spacer between the magnetic rings and thick paper ring with tabs that holds them in place. The centering strings now work fine.

[Zenith6S321]

I went through the chroma alignment. Only one adjustment needed tweaking. The set came without chassis hold-down bolts so I bought some that seem to do the job ok. I bolted the chassis and tuner in. About half of the plastic knobs snapped in half when I originally tried to pull them off. I used some epoxy for plastics and with some fiddling got them back on. I had to substitute an old knob for the color level control as it was missing. The UHF numbered dial indicator knob is missing. I only plan on using channels 3 or 4 but I'll keep an eye out for one if I can find a picture of what it looks like. I went through purity and convergence again. I still need to come up with a way to hold convergence pole pieces in alignment over the guns. Next I'm going to make mounting plate for a fan to get cool air into the HV cage. I plan to remove the rivet the access cover pivots on, remove it, and screw the fan plate in its place.

[Zenith6S321]

The first two pictures are of the fan I added to exhaust hot air from the top of the HV cage. The 12VDC fan is powered from the 6.3V filaments through a voltage doubler rectifier. I put the fan where it would exhaust the hot air generated by the HV regulator tube. There is a slot in the plastic plate that the fan mounts to. The slot is where the air enters. I epoxied a smaller piece of plastic to direct the cool intake air to the flyback first. So the flyback gets the cool intake air, then it goes by the HV rectifier, then the regulator heats it, the hot air rises and the exhaust fan pulls it out the top. I watched a 2 hour movie on the set last night and then felt the flyback right afterwards. The flyback was barely warm.

The last two pictures are of a ring of plastic with Velcro to hold the convergence pole pieces in alignment over the guns and to keep them from flopping over. The springs keep the pole pieces against the CRT neck but also made them want to flop over. Not the greatest solution, but it works ok.

Dave

[Kevin Kuehn]

This is a 3/4" wide Velcro wrap that I use for holding battery packs in my planes. I forget exactly what it's called, but it comes several feet on a roll. Seems to be self stabilizing, and you can tension it up a little.

[Username1]

Hey- that velcro wrap looks wide enough to be pretty stable.... Good thinking ! !
Simple fix too ! Always best.

.

[Kevin Kuehn]

Well it seems simple, but I'm not sure how critical the magnet spacing around the neck circumference will be? My cloverleaf is only broken in the one location, so it's throwing the magnet spacing off a little. I guess I'll find out when it's time to do a convergence. In the mean time it's doing a decent job of holding everything in place.

[Zenith6S321]

Originally Posted by Kevin Kuehn

Well it seems simple, but I'm not sure how critical the magnet spacing around the neck circumference will be? My cloverleaf is only broken in the one location, so it's throwing the magnet spacing off a little. I guess I'll find out when it's time to do a convergence. In the mean time it's doing a decent job of holding everything in place.

That does look like a better option than my fix. I was concerned about the spacing but now I'm not sure it makes that much difference as long as the two pole pieces of each convergence coil is over their respective gun pole pieces just inside the CRT.

Dave

[Kevin Kuehn]

Originally Posted by Zenith6S321

I was concerned about the spacing but now I'm not sure it makes that much difference as long as the two pole pieces of each convergence coil is over their respective gun pole pieces just inside the CRT.

Dave

Dave, that's good to know. One could take this one step further and put a piece of adhesive Velcro on top of each magnet assembly(similar to what you have) and then wrapping the strap around the outside. That should help stabilize the spacing.

[Zenith6S321]

Here are some pictures of the results of the restoration. The convergence is certainly a compromise. The multiburst shows video response through 3 MHz with 3.58 filtered out and maybe just a little at 4 MHz. I added a 22 uH choke in the screen circuit of the video output pentode patterned after a later Zenith set with a peaking adjustment.

Dave

[Kevin Kuehn]

Looks very nice from here. Is the Ovation software by chance a free download?

[Zenith6S321]

Actually its an old DVD titled "Avia Guide to Home Theater" 1998-1999 by Ovation Software Inc.