Hi there, I have one of the cylindrical early 70s Toshiba RC-693F clocks. It lights up but the numbers won’t flip over; it’s frozen at the same time. May I please ask the advice of you experts on how to repair it?
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I have restored one of these (red color). Typical issue for the motor in this and pretty much all other flip clocks. The clock movement and motor will need to be removed and lubricated in a couple of key areas, but disassembling the cabinet is tricky due to how densely populated it is on this unit. Unfortunately, I do not have any pictures of this restoration, but it shares the same movement and motor assembly as many other Copal-equipped flip clocks.
Edit: Found an internal pic of one: https://www.radiomuseum.org/r/toshiba_rc_693f.html
That shows the motor assembly under the aluminum cover that has a sticker with "Copal" on it. (Make sure it is unplugged) The cover must be removed and then you can gain access to the motor. The power wires to the motor are fairly short so it will be difficult to maneuver the motor assembly. -
*thank you* for the tips on what’s wrong and what kind of movement it has! Will give the repair a try. Exciting that you have successfully restored a red one; it sounds gorgeous ☺️Comment
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Once the motor assembly is removed you'll see the "stator wheel", which is the external wheel of the motor. it has a magnet along the internal circumference that interacts with a coil. It's called a field-coil motor. The magnetic field rotates a certain direction and "grabs" the magnet in the wheel.
Anyhow, I have attached some pics of a motor that has been taken apart. so you can see where lubrication is needed. NOTE: You do NOT need to disassemble the motor.
The motors were never designed to be refurbished. They were just designed to be used and replaced if they died. The problem you describe is due to old lubrication and dirt uniting to make the motors stop spinning. I don't recommend the alcohol soak (mentioned in posts here in the past) any longer as it seems to have a reaction to the adhesive of the magnets on the inside of the stator wheel sometimes.
That being said, the only solution is synthetic lube/oil. A good oil to use is one used in the firearms industry called BreakFree CLP-4. It's made for dirty environments and keeps dirt and other debris suspended. Easier to get is synthetic 5w-30 motor oil and it works well, too. You'll see there are brass bushings pressed into the motor body with a small polished washer between it and the stator wheel. That's where the problem is coming from. That washer is "galling" which causes chatter from low or non-existent lubrication. It also causes drag which is most likely your issue.
The best way to lubricate that area (since you can't pull the motor apart) is to lube through the holes in the stator wheel. You have to really flood it with lube because there is a lip that surrounds the area where the lubrication needs to flow. I have attached some pics. One shows the stator wheel removed and the "lip" that you need to get lubricant to bypass. The other pic shows another area that needs lube where the brass spindle gear is located. The gear is removed in that pic. Hope this helps!Comment
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- grateful to you for this thorough overview! The photos are very helpful, as well. If the gun oil you mentioned isn’t available will try the lightweight synthetic motor oil you recommended instead.
Sure appreciate you taking the time to help me ♥️
Going to try the repair this weekend... will share some photos when it’s done!Comment
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AnnieLA Happy to help. Just take your time with it.
Another thing to note. Sometimes the motors will have a yellowish plastic cover that covers the gearbox side of the motor assembly. That will need to be removed. Many times it must be broken into pieces to be removed due to the plastic being terribly brittle after 40+ years. It's merely a dust cover and it is fine for it to be removed and not replaced. It will shatter as you pick at it so make sure pieces don't get stuck in the gears.
Some motors have a metal cover instead of plastic. It seems that later versions of the motor had the plastic cover so yours may be metal.
If you need any help just ask.Comment
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