11/29/2021
I just straightened the plates in the tuning capacitor of a Clarion JR AC-60 cathedral radio. It wasn’t easy. This is a huge old three gang tuning capacitor with 24 plates in each section. 36 plates in the stators, 36 plates in the rotors. Just about all of them were touching between rotor and stator. The only way to get this straightened was to remove it from the chassis. I connected each section individually to a continuity tester, turned the tuning control, listened and used a bright light to carefully bent the plates in the rotors and stators, where they were touching and the tester was beeping. It’s kind of like adjusting spokes on a bent bicycle wheel. But sometimes adjustments had to be made in a few different places on the same plate. After a few hours of careful bending (manipulating plates) no beeping was heard from the continuity tester as each section was tuned through it’s entire range. After re-installing the tuning capacitor into the chassis the radio now works very well. I also lubricated the tuning cpacitor bearings. Another reason why the tuning capacitors have to be disconnected is because each one has an RF coil (actually a transformer) winding connected to it, which kind of looks like a short circuit, masking any continuity readings.
I also had to replace all 11 capacitors wax potted capacitors. A huge can on top of the chassis contained and still contains the 5 filter capacitors. New film types are much tinier. So they fit under the chassis. My customer didn’t need them to be replaced inside the capacitor can. But if anyone wanted them to be replaced inside the cans, I could do that for an extra charge. There were two smaller cans on the inside of one of the sides of the chassis each containing and still containing 3 “bypass” capacitors. These cans are actually box shaped. One, or more, of the filter capacitors probably overheated in the past because a huge pile of wax had dripped out of the filter capacitor can and was on the inside of the chassis’ bottom cover. It was easy to remove.
I forgot to say this earlier:
There were three screws holding in this tuning capacitor (there still are) and 4 wires to disconnect. But in order to get to two of the screws, the covers had to be removed from two of the RF transformers and one of the two RF coils had to be removed from the chassis and moved out of the way to get to the screw. But the RF coil didn’t have to be disconnected to do this, just angled slightly to get a screwdriver in there to remove the screw.
This was done in reverse to put the tuning capacitor back into the chassis.
If anyone wants to hear the radio playing I can send a short video of it playing via private message. I’ll post some pictures later.
