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Electronics => Repair => Topic started by: james_s on August 25, 2018, 04:05:03 pm

Title: Tamura Lumitime clock mechanism
Post by: james_s on August 25, 2018, 04:05:03 pm
I recently picked up a Lumitime clock, this is an early digital clock from the 1970s which uses a motorized mechanism of gears and contacts to switch power to NE-2 lamps forming 7-segment digits. There were numerous different models, most of which used the same internal mechanism. Mine was in need of some significant TLC so I took apart the motor and first set of reduction gears to clean out all the dried up old grease and get things moving again. Unfortunately there turned out to be two tiny washers, one felt and one plastic that ended up on the table and now I'm not sure where these go. Has anyone worked on one of these and perhaps made some notes on where the washers go?

The other issue is that the pawl behind the rotor that prevents the synchronous motor from starting in reverse had essentially crumbled into dust. It would be great if I could find a picture of what that is supposed to look like, it may be possible to fabricate something to replace it.

These clocks are quite collectible, good working ones often fetch >$100 and the motor is a known trouble point however there seems to be surprisingly little detailed information out there.
Title: Re: Tamura Lumitime clock mechanism
Post by: amyk on August 25, 2018, 05:48:41 pm
Post pictures please...

This is the only relevant service information I could find but it's unfortunately $$$: (
Title: Re: Tamura Lumitime clock mechanism
Post by: james_s on August 25, 2018, 06:15:16 pm
Unfortunately I didn't take many pictures when I had it apart, had I had the sense to do that, I'd have avoided this situation in the first place.

I'd be ok paying for a manual if I knew it was for the right thing and had the information I need, however the "Lumitime" name was used on a lot of products including later LED digital clocks and clock radios. I suppose I could keep an eye out for another similar clock and more carefully disassemble that one, hopefully getting both going.

I replaced all the neon bulbs in it as I had to desolder them all to get the frame off the PCB to replace a bad resistor and reinstalling the old bulbs with very short leads was almost impossible. About a dozen of them were in bad shape and heavily darkened, mostly those that are on the most. Curiously though the two that are lit continuously to illuminate the starburst were in great shape, I don't know why they held up so well. These are run with 39k resistors on 120V which strikes me as driving them pretty hard, makes me wonder if they should be NE-2H lamps but I had a whole bag of regular NE-2 so I used those for now.