Service Manual.                                                                                                                                 Bulletin 537.


  1. This Master-Program clock operates from a 120 volt, 60 cycle, single phase, power supply. It requires little attention and no special knowledge beyond these few basic instructions.
  2. An industrial-type, synchronous motor provides the time-keeping function and drives the program tapes, the clock hands, and the cams for operating the control switches.
  3. A low-voltage, current limiting transformer has been provided for the safety of personnel setting the program schedules.
  4. A secondary-clock switch, marked "A", has been provided to shut off power to these circuits when desired.
  5. A spring-reserve assembly keeps the Master Clock in operation without rewindng during accumulated (or single) power failures of up to 15 hours' duration. The de-energization of a flag coil automatically trips the balance wheel to start the spring-reserve when power fails, and stops it upon return of power. (Be sure to remove the elastic band - used to secure the flag coil during shipment on new installations).
  6. A red flag appears on the clock dial when main a-c power fails. When power is restored, this flag should be manually reset by means of the red lever located below the motor switch. Its reappearance then indicates the occurence of subsequent power failures.
  7. For single power-outages of greater duration than 15 hours, the spring-reserve assembly may be manually rewound to extend the driving time on models provided with winding keys. Such units should be checked and rewound annually.
  8. On automatically-rewound, spring-reserve units, the reserve running time is slightly longer and no attention need be given these units. Where single power failures of longer periods than 30 hours occur, or where the Master-Clock has stopped, the resetting may be easily accomplished by turning "OFF" the secondary-clock switch, "A", rotating the knurled knob on the center of the program-tape-sprocket drum until the dial hands read correct time, and then turning "ON" switch, "A", again. Refer to items 9 and 10.
  9. Secondary clocks will stop during a power failure. For single power-outages of 25 minutes or less, the secondary clocks will automatically reset to correct time on the next 59th minute.
  10. If power is off for longer than 25 minutes, the secondary clocks must be reset by manually operating the reset push-button. Each depression of the reset push-button switch will advance the secondary clocks one minute, e.g., 60 depressions = one hour advance.
  11. To set up a program schedule, proceed as follows:
                        a. Throw all circuit switches to "OFF".
                        b. Remove the tapes by first unwinding them from the spools and then from the sprocket-drum. Raise the tape up from the top of the drum to clear the sprocket pins and use care that the contact fingers do not catch.
                        c. Punch out the entire printed rectangle in which the minutes are printed, using the punch provided. Make sure the proper hour - (night hours have an "N" printed after them) is selected before punching out the minute spaces. If a space is punched out in error, do not patch the hole. Use a new tape (tapes are supplied free or for a nominal charge).
                        d. Replace the tapes on the sprocket drum so the figures are right side up when viewed from the right-hand side of the drum. Circuit No. 1 is on the outermost position.
                        e. The contact fingers should indicate the same time on the tape as is indicated by the Master Clock hands.
                         f. Make sure that the calendar drum is set for the correct 12-Hour period. (This drum advances at 6:00 A.M. and at 6:00 P.M.). See Note 2.
                        g. To set the calendar drum, lift the advance lever at the rear of the drum with the right thumb and index finger. Then rotate the calendar drum as desired. Release the lever. If the lever advances the drum on release, repeat the operation and set the calendar drum on the preceding position before releasing the lever. Check the vertical alignment of top or bottom row of calendar pins.
                        h. Throw all circuit switches to "ON".
                        i. A master pushbutton switch is provided on the front door for manually energizing each circuit or schedule.
  12. At the start of a Daylight Saving period, turn "OFF" the secondary-clock switch, "A", on the half hour. Then carefully rotate the knurled knob in the center of the tape-sprocket drum in a clockwise direction until the dial hands are advanced one hour. Then turn switch "A" back "ON" and depress the "RESET" switch, "E", 60 times. The secondary clocks will then correct to true time on the next 59th minute. If the knurled knob was turned too far, turn "OFF" the clock drive motor until time is correct. (Then turn "ON" again.)
  13. At the end of a Daylight Saving period, turn "OFF" the synchronous drive motor switch (at the motor) and switch, "A", on the half-hour. Turn "ON" again after 60 minutes (on the next half hour). If, inadvertently, the switches are not turned "ON" at the proper time, the Master Program Clock may be set to correct time by rotating the knurled knob in the center of the program drum. The secondary clocks may be advanced one minute for each depression of the manual reset pushbutton.

Note 1. If no programs are provided with the Master Clock, disregard item 11.

Note 2: Advancement of the calendar drum at 12-Hour intervals allows silencing during any day or night period.

Note 3: In case of trouble, please contact our nearest office at the address given on the red sticker.


Webmaster Notes: I have this model Master Clock, and these instructions are printed on the inside case of the clock.  A picture of this type of master clock is on the "Author's Collection" page.  Some models have round faces, my clock has a square face.

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