First Time Clock Repair
Basic battery operated clock repair can be relatively easy if you just remember two things; clock parts are not as standardized as you would think, and many clock movements look alike, as they a just a small, normally about 2-1/8" square black box..
Trying to cross reference any part numbers that may be on the back of the movement can also be a problem because there is no cross referencing guide and some companies that export into the U.S. actually put the same part number on several versions of the same clock movement, which can further confuse the issue.
The good news is that as long as you can measure to within a sixteenth of an inch (1/16") then you can replace a clock movement. The primary consideration is the length of the hand shaft, which contains the hour, minute and second hand shafts, and you need to know how thick the clock dial material is on your clock case when measured at the center hole of the clock dial. You can put a pencil through this hole, mark the front and the back, then pull it out and measure with a ruler to get the clock dial thickness.
Get the right ruler:
Please reference the two rulers shown below (Drawing A). If the ruler you have has a "lip" at the end, it will not give you accurate measurements. You need to use a ruler with a "zero point" at the end.
Most AA Powered Clock Movements Look About The Same (Drawing B):
Most AA battery powered clock movements basically look about the same from the back. Most of these AA battery powered movements are either 2-1/8" square or 2-3/16" square and 5/8" thick, but the length and diameter of the hand shafts will vary widely. From the back while still installed in your clock case they normally look like the picture below.
Let's Get Started By Removing Your Clock Movement:
Before you can begin the process of putting a new battery operated movement into your clock case, you will need to remove the clock movement that you have from the case it is mounted into. The reason is simple, to much important information about your clock movement hand shaft is hidden from your eyes, when the movement is still installed into your clock case.
The clock hands come off first. In almost all cases, if your clock movement has a second hand, it can be removed simply by pulling it out at the "hub" where it attaches to the clock movement. Please reference Drawing C.
The minute hand (the longer one) comes off next. Sometimes they are just pressed on and can be removed by simply reversing the process. Often the minute hand is held in place by a small round nut. If this is the case, you should hold the tip of the minute hand while turning this small round nut in a counter clockwise manner. If you do not hold the tip of the minute hand still, you could end up turning the small nut forever, as without one end being held still the small nut will just endlessly keep turning.
In most cases the hour hand also just presses on, so you can simply pull it off. You can always take pair of needle nosed pliers, squeeze them until they are fairly tight around the movement shaft, and then just pull upwards. Since it is unlikely that you will be re using the clock hands, do not worry about damaging them as you cannot replace the movement without removing the clock hands first.
Let's Define What You Need:
If your clock only tells time, then it has a "Time Only Movement", if your clock has a minute hand (the longer one) that is 7" or longer, then you need a "High torque Time Only Movement". Clock hand measurements are always based on the length of your minute hand, measured from the center of the mounting hole to the tip of the minute hand. Hour hands are normally 2/3 the length of the minute hand, depending of the style of the hands. In most cases if your clock has a second hand, then it would normally be about the same length as your minute hand.
If your clock has clock hands that are 5" or less, then a "Mini Quartz time only movement" will suit your needs just fine.
Let's Continue By Taking Some Accurate Measurements:
I cannot stress strongly enough how important it is to have an accurate ruler! You need a ruler that starts at zero. May rulers have a small "lip" at the end, which makes it almost impossible to take the small accurate measurements that will be needed. A tape measure is not much better, as often the clip at the end becomes loose, also resulting in inaccurate measurements.
Please refer to Drawing D below. This shows our MVT7190A with a 7/16 threaded shaft and a ¾" overall shaft. This basic Time Only Mini Quartz Movement is actually available in 6 different shaft lengths-two shorter and three longer. Now take the same measurements on the movement you have removed from your case. Once you have these measurements you are ready to access the following links:
Link to Mini Quartz Movements
Link to High Torque Movements
In both of these links there is an additional link to hour and minute hands. For the Mini Quartz Movements a choice of about 50 pairs of hour and minute hands are included the movement price. For High Torque movements the hands are available at an addition cost. In both cases at the top of the hand link are drawings showing the exact hole sizes that are required.
We hope that this information allows you to properly replace your worn out quartz movement. If you need additional assistance, please contact me at: mike@hous.com
Regards,
Mike
Brosman
ISI/hous.com
