Below are the six pages of intructions that came with the original clock in Adobe Acrobat pdf format.
We are happy to continue repairing these clocks for you even though most of them are 40 years old. We realize how much you love them and that you are passing them down from generation to generation. You will get better and more economical repairs from us than anyone else. Nevertheless, even though I have no plans to retire and hope to last another 10 years, and will just be working less as I get older (I am 75 in 2015, now) the following is provided so that even your great great grand children can keep them going if they desire.
This link below, "Repair Hints," is for the do-it-yourself types who want to repair the clock themselves. Or you should be able to download this page, print it out, and give it to a repair tech along with the appropriate schematic, also below, to fix it for you.
The schematics below are really not very important when it comes to repairing these clocks but they will make anyone repairing them feel a little more secure. The important info is in the "Repair Hints" link above.
Below are some of the electronic schematics for the Dot Clock. On the back of each clock there is a datecode--serial#. The date codes are the first 3 digits. The first digit of the date code was the year of some change, the next two digits was the week of that year. The clock was first made in 1971. Production stopped in 1981. The sequence of the date codes were, 147, 208, 224, 247, 300, 511, 540, 620, 011, 019.
Most of the changes were very small. The schematics with the more major changes are below.
Only 25 of date code 147 were made and I haven't seen one for repair in 15 years. The main difference between it and 224 was it used a self-latching reed relay in the middle of the left side to turn the clock ON.
Date code 208 used a slightly different self-latching reed switch (not relay).
Date code 247 change the way it reset itself going from 12 to 1 o'clock
Date code 300 change the way it reset itself going from 12 to 1 again. Also a second diode was added in series with the emitter of the 2N3643. Also the sequence of the first two counting IC's were reversed. Date code 511 is the closest.
Date code 620 is similar to 019 but uses a separate schmidt trigger filter on the 60Hz input that is being counted.
Date code 011 has a design problem that was rectified in 019. Any of these found with 150K resistor on the input, pin 10, of the 4020 IC should have the resistor changed to 82K.
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