1963 Zenith 29JC20 restoration

[Zenith6S321]

When I first tested the set, the fine tuning did not have much effect. I removed the tuner side cover and saw that a plastic gear engages a fine tuning screw on each channel coil insert. The plastic gear had split down its length. A goggle search for 14 tooth 1/4" diameter with a 1/8" inside diameter 3/8" long gear shaft turned up everything but what I needed. I could epoxy it, but that would probably fill up the gear teeth which might cause more splits. If I could find the right inside diameter c-clip/cir-clip I might be able to put it around one end of the gear and fit it into the tuner, but there is not much room in there. I noticed that only about half the length of the gear had dark grease marks on it from engaging the tuner screws. So I'm going to experiment with using some heat shrink tubing to squeeze the gear at the end that does not seem to engage the tuner screws. Here are some pictures of the split gear, the gear with two layers of heat shrink on one end, and with it mounted back on its shaft. The shaft has teeth that engage the inside of the plastic gear. The shaft is driven by the fine tuning knob and the mechanism moves the gear to engage it into the tuner screw teeth. The gear now fits snuggly on its shaft and works surprisingly well, for now...

Dave

[Zenith6S321]

I made an attempt modify the broken cloverleaf to get the convergence coils closer to the right positions. I cut the cloverleaf coil support section apart and put springs between them. The put it back together, but its really too floppy and needs more work. I wanted to make an initial attempt at getting some kind of picture. I quickly set purity and convergence. The tuner now sort of works. Here are pictures of the cloverleaf and the first pictures using channel 3 RF. When the set is first turned on I get some color but it quickly fades away after a few minutes. There is also quite a bit of ringing in the video when there a large image contrast changes. I will take a look at it on my scope. Probably will need to do an IF alignment, or maybe its just a wiring mistake I made.

Dave

[old_coot88]

I've fixed mucho many of those FT gears that 'd split. Just clean the shaft and gear thoroughly of all grease. Then apply epoxy sparingly to only the splined area of the shaft using something like a toothpick, and slide the gear back on. Never had one fail.

Re. the cloverleaf, back in the day there was an aftermarket item for that, consisting of a bungee sized to fit snugly around the outside perimeter. What you're doing is just as good, probably better.

[Zenith6S321]

Originally Posted by old_coot88

I've fixed mucho many of those FT gears that 'd split. Just clean the shaft and gear thoroughly of all grease. Then apply epoxy sparingly to only the splined area of the shaft using something like a toothpick, and slide the gear back on. Never had one fail.

Re. the cloverleaf, back in the day there was an aftermarket item for that, consisting of a bungee sized to fit snugly around the outside perimeter. What you're doing is just as good, probably better.

Thanks for the tuner gear tip!

Dave