Architectural Clock Support

National Time and Signal is committed to customer satisfaction and will provide technical support for all our our past and future products.

For detailed instructional and troubleshooting videos on National's architectural clock products, please visit our YouTube channel.

National Time & Signal Correction Series Clock Mechanism Troubleshooting Basics:

X-10 series clocks will run at 10 time’s normal speed when in reset mode thereby advancing 1 hour in 6 minutes. Clock problems are either electrical or mechanical – possibly both. Some repairs can be completed with replacement components being sent while others require return to the factory. The electrical components of the clocks are the mechanism motor and reset controls. The reset controls are either by means of a manual switch or a solid state automatic clock controller. These controls allow the clock to be reset electrically from an accessible location without having to access the clock hands or mechanism. The mechanical component is the mechanism or gearbox in which the motor is attached.

Initial basic information required for all clock service or repair diagnosis:

Model # of clock mechanism or pictures if unknown.
Serial # of clock – if no label is visible on the housing, look for black ink stamps typically 4 or 5 digit inside housing and/or on the mechanism or motor. 2MR Series will have a month/year date code or 3 letters.
Type of clock control: Does clock(s) have NORMAL-OFF-RESET manual reset switch or a Model number MC3 / MC100 automatic controller with a digital display?
Does the clock advance in either normal or reset modes?
If the clock advances in normal mode, does the clock advance an hour in an hour even if not displaying the correct time?

The majority of our clock mechanisms dating back to the 1930’s can be repaired with basic components like sending a new motor to you or sending the mechanism in for mechanical related repairs. However, some installations can justify the cost of purchasing a replacement mechanism. These conditions may include:

Accessing the clock one time only to swap out the unit in lieu of multiple trips to the site for removal and return to reinstall once repaired should the mechanism require factory service.
Weighing costs associated to difficult access to the clock or hand removal requiring special equipment such as lifts or scaffolding.
Closure of sidewalks or streets.
A multi clock installation in which purchasing a new mechanism enables swapping the original mechanism out with new at the same time. The original clock mechanism can them be repaired prior to the eventual necessity of servicing of another clock within the same installation. The repaired mechanism can then be used as a “rotator” for swapping.

Initial information required for all clock service or repair diagnosis

Model # of clock mechanism or pictures if unknown.
Serial # of clock – if no label on housing, look for black ink stamps typically 4 or 5 digit inside housing and/or on the motor.
Does clock(s) have manual reset switch or an automatic controller with a digital display? Model MC3 or MC100.
Does the clock advance in both normal and reset modes?
If the clock advances in normal mode, does the clock advance an hour in an hour even if not displaying the correct time?
Does clock advance in reset mode?

Helpful Documents

#	Type	Name/Description	File size	View / Download
1	PDF	468 - MC3 and WeMC3 Master Clocks	1.6 MB	View
2	PDF	MC3 Spec Sheet	474 KB	View
3	PDF	MC3 Operation Manual	493 KB	View
4	PDF	MC100 Operation Manual	101 KB	View

Troubleshooting 2M Series or 2MR Series

2M Series (single 1 RPM motor) or 2MR Series (remote resettable - 1 RPM & 10 RPM dual motor)

The 2M series clock is not resettable electrically and must change the time by turning the minute hand and the hour hand will follow until the correct time is displayed. The 2MR series can be set in the same manner as the 2M or electrically manipulated with a manual #970 reset switch or #MC3/MC100 automatic controllers.

Most common repairs include:

Regular run 1 RPM motor failure. This motor has two black wires. If the clock does not advance at all in normal operation setting but does advance a complete hour revolution in reset mode. This 1 RPM motor runs continuously so it ultimately fails over time. Replacement 1 RPM motor is our part #9030. The other 10 RPM motor found on 2MR series clocks with remote reset ability has orange wires and only runs in reset mode when correction is needed. This motor typically does not fail and lasts much longer. Some prefer to replace both when the 1 RPM fails as a precautionary measure. Replacement 10 RPM motor is our part #9031. Both motors have a hexagon drive pinion.
Potential worn worm or worm gear if the clock does not advance in either NORMAL or RESET mode. Inspect gearing for signs of wear or brass dust inside the gearbox. Causes of this failure are typically associated to resistance such as:
1. Hands making contact with the dial, cover glass or one another.
2. Unbalanced hands.
3. Overtightening of the hour hand set screws causing the brass hour shaft to collapse and make contact with the minute shaft.
Replacement will require removing and measuring the overall length of the minute shaft to which the worm gear is attached. Remove the rear plate to pull the minute shaft out for overall measurement. Our part #AY-850/851-XX (measured length) or return to factory for repair.
Clock controller settings are not correct. Must be programmed for “NATSCO X-10”. See associated manual.

Troubleshooting 3MR, HMR, KMQR, 4MR, 4MQR Series clock mechanisms:

These clocks use a reversible synchronous motor with two coils and will turn at a speed of 10 RPM in either direction. When placed in reset mode, the motor shaft reverses direction and shifts the mechanism into a different gear which speeds up the hands to a 10 times normal speed. Synchronous motors do not run slow. They typically stop all together but can occasionally start and stop intermittently thereby loosing time. If a clock is slowly loosing time, it will likely be a component wear type of problem.