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Old 20-04-19, 21:48
David Dunlop David Dunlop is offline
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Join Date: Feb 2006
Location: Winnipeg, MB
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In my last post I mentioned some spin off work for the Slow Motion Tuning Drive turned up while I was replacing the Handles No. 72 on my Main Set Receiver.

I had noticed a while ago the Slow Motion Drive seemed a bit stiffer than it should have been to operate and when the Flick Control Lever to the right of the tuning dial was in it’s lower FLICK position, I needed two hands to turn the dial, which by rights should turn very freely with one hand with the control lever turned to that mode. My thought at the time was that since the Slow Motion Drive worked, but was very stiff, the problem was probably with one of the tuning shaft support bearings, fore and aft on the tuning condenser assembly. While working on the Handles No. 72, I decided to take advantage of the strip down and remove the large tuning dial to give it a proper clean. This necessitated removal of the Slow Motion Drive Assembly at the bottom of the dial. This is another of those tasks that can be intimidating because of the Bracket and Spring Assemblies No. C1 (ZA/CAN 0233) the Slow Motion Drive is mounted in and the fact there is a lower arm of the Flick Mechanism connected to the Slow Motion Drive one has to be aware of while removing and installing the drive unit. Again, this is another bit of work that you should let gravity help you with. Place the receiver on its back before you start.

The first two photos are of a standard drive and a Slow Motion Drive assembly. The stud on the lower right hand side of each it what engages into a large, self-locating V-Slot on the end of the lower Flick Lever. When everything is installed, and you turn the Flick Control Lever to the ‘FLICK’ position, the lower Flick Lever (which is spring loaded to keep it under tension, pushed the right hand side of the Drive Assembly away from the rim of the large tuning dial. The allows the operator to grab the Handles No. 72 and turn the dial rapidly to one of the preselected frequencies. When that position on the dial is reached, an Upper Flick Lever, coming from the Flick Control up to the two Indicator Flags Mechanism drops the appropriate Indicator Flag down for either the A or B Frequency being selected.

Because of the orientation of the Lower Flick Lever, and the fact it is under spring tension, if there is no Tuning Drive in place for it to engage, it will automatically swing to the left, across the small rectangular opening in the panel behind the drive assembly, when you remove the drive. Don’t look for it on the right side later. It won’t be there.

Before you start, make sure the Flick Control Lever is in its middle SET position and leave it there. First step it to remove the knobs from the drive. Then remove the long pivot screw at the left side of the Bracket and Spring Assemblies. It is a good idea to keep a thumb on the assemblies, just to the right of the pivot screw as you remove it. To keep everything in place until you are ready. You will notice as the screw comes out of the panel, the Bracket and Spring Assemblies relaxes and a small bend shows up along the lower edge. At this point, slowly lift the Assemblies away from the panel. About 1/8-inch away from the panel you should feel the locking stud, about ½-inch to the right of the pivot pin pop free of the panel. When it does, slowly move the Assemblies up and to the left at a shallow angle. You should notice the Lower Flick Lever following along for a while and then disengaging and swinging off to the left of the rectangular hole.

To replace the complete Drive, Bracket and Spring Assemblies No. C1, start by putting the long pivot pin in place to keep the two parts together. With a small little hook, retrieve the Lower Flick Lever from the left side of the little rectangle. As you move it slowly to the right, you will see the large V-opening appear with a rounded apex to the V. Insert the stud on the lower left end of the tuning drive into the V-opening, left the lever engage it and move the entire assembly into position such that the long pivot screw can be engaged in it’s hole and threaded home. The manuals will tell you to run the pivot screw completely home before the next step, but that just make the next step that much harder for you to complete.

The small locking stud to the right of the pivot screw rests very quickly on the top of the panel face. If you run the pivot screw completely home first, that small stud really digs in and you are making a lot more work for yourself. Don’t worry about getting the rim of the large tuning dial into its slot on the central pin of the drive assembly. If you miss it initially, it should pop into place as you tighten to pivot screw.

The last step the manual will advise you to do is insert a small slotted screw driver under the Bracket and Spring Assemblies, engage the end of the small locking stud and push it up about one half inch until it pops into its locking hole. I find a much better solution is to use a thin steel putty knife as shown in the third photograph. If you have to, remove any switch knobs in the area to make things easier for you. I usually tighten the pivot screw down just far enough I can slide the putty knife blade under it easily. The really nice thing about the putty knife is it has a wide blade and you will not miss finding the small locking stud. That spring on the Bracket and Spring Assemblies No. C1 has a surprising amount of tension in as you move it closer to its panel hole. The bottom edge of the assembly should be perfectly straight when you get to the hole. Once it has dropped in place, remove the putty knife, finish tightening the pivot screw, reinstall the tuning knobs and any others you had to remove and you are good to go.

Sorry for the length of this. Hope it proves helpful.

David
Attached Thumbnails
Tuning Drive Assemblies A.JPG   Tuning Drive Assemblies B.JPG   Tool for Bracket and Spring Assemblies No. C1.JPG  

Last edited by David Dunlop; 21-04-19 at 00:36.
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