[Phlogiston]

I suspect that the broken part is rubber that has hardened, which explains the condition and inability to piece it back together.

[Eliot Ness]

Find a rubber automotive hose with the right size inside diameter, the outside diameter won't matter as much. This method is used for similar assemblies in AK radios and works well.

That's the best idea yet...... don't why I didn't think about it since i have used it on AK's..... that's why Russ and Terry get paid the big bucks as PTC's (Phorum technical consultants) 

[captainclock1988]

I like the hose idea. No groves necessary.

I tried using a rubber grommet that was the same inner diameter as the shaft on the flywheel and the belt kept slipping on the surface of the grommet because it was too slippery (no traction ridges like the original plastic piece had) so with that in mind, what makes you think a rubber automotive hose would be any different?

[rfeenstra]

I've had no problem with rubber against rubber slipping. Maybe your belt was too loose. Try a flat belt.

[Phlogiston]

Well you could cut groves into the rubber, but I wouldn't. Better to use a hose with a larger outside diameter and use a piece of course sand paper to roughen up the outside surface. Is there no way to increase the tension? Most Zeniths have a spring/roller tensioner. One of the new silicone belts would be a good idea too.

[captainclock1988]

I've had no problem with rubber against rubber slipping. Maybe your belt was too loose. Try a flat belt.

I was using a flat belt, it was a flat belt I pulled out of an old VCR I junked out, it was basically the same size as the one that would of been on there originally (about a 2" belt), and it still slipped.

[captainclock1988]

I suspect that the broken part is rubber that has hardened, which explains the condition and inability to piece it back together.

Hardened Rubber would make more sense as it does seem to be behaving a lot more like old hardened rubber than old plastic.

I guess I could try rubber hose, I'll see what I can find at my local Auto Zone and go from there.

[Steve D]

I have a 10S669 which uses the same chassis as the 10S690 and while someone added electrical tape to try to get more friction when the belt got brittle, the factory design used a flat leather belt that was driven by the knurled portion of the brass shaft.

   

I replaced the leather belt with a flat rubber belt that came as a kit which you cut to size and super glue together. It took a couple of tries to get the length optimized but it has been working for over 10 years without slipping. 

Steve D

[Phlogiston]

I don't know if that guy still sells that square belt material, but I think you can get it from auto parts stores (Napa). I would not try to purchase one of the NOS belts, even unused ones have become brittle. I glued up a few of those, still prefer one of the new belts.

[captainclock1988]

Now McMaster-Carr has some leather flat belts that you can buy at various lengths and widths but the problem with theirs is that they come cut in half and you have to splice them togehter using special splicing material (according to their website anyways.)

See link below

McMaster-Carr Flat Belt Selection

[captainclock1988]

UPDATE: I finally fixed the tuner belt problem, I ended up using a rubber grommit with the correct inner diameter that was from a rubber grommit assortment kit I picked up at Harbor Freight and just stuck that onto the flywheel shaft where that knurled piece of rubber used to be and then just used an appropriately sized square belt that I had left over from an old VCR I junked out and the groove on the outside of the rubber grommit acted like a track for the belt to ride on and so now it works as it should!   

See picture below for a view of the repair.

   

[RodB]

Nice fit, plenty of traction there.

[captainclock1988]

Yes, I agree, its more or less a miniature rubberized pulley, where you have your groove track for your belt to ride in just like you do on the bigger pulley that drives the tuning capacitor.   

I've got some capacitors on order for this radio so then I can recap this radio and then it will work as good as new again, I even managed to properly repair the band switch which was broken on my radio because one of the rivets that held one of the pivot joints together for the band switch was broken and the previous owners of the radio attempted to repair it with a 4-40 screw and 2 nuts to hold it all together but the nuts kept coming lose which made the band switch have too much slop to it whenever you would change bands.

[captainclock1988]

OK, so I have an issue that just popped up with my Zenith radio, I just finished recapping the radio and went to test it out and for some reason the volume control is acting like a tone control knob rather than a volume control knob and I tried to pay attention to where all the caps went and everything, and I can't figure out where the volume control and tone control circuits are on the schematic to see if I may have wired something up wrong or put a wrong value capacitor in somewhere.

Other than that everything is working as it should.

Any help would be appreciated in this matter.

See schematic below.

Zenith 10S690 Service Manual_Riders.pdf Size: 190.41 KB  Downloads: 180

[RodB]

Take a look at the parts list. Volume control is R12 with C14 attached to the center terminal. R12 has a couple taps for tone control.