May 1, 2007

As locksmiths, our customer/employers expect us to provide service for their locks and door hardware. We need to know how to change the combination or service all kinds of mechanical and electromechanical locks.

The Simplex 900 Series by Kaba Access Control is a pushbutton mechanical lock that has been produced for many years. It is available in a number of configurations including deadbolt and deadlocking latch. These pushbutton locks can be programmed to unlock when pressing one button or a sequence of up to all five buttons. In addition, two or more buttons can be pressed at the same time. However, each button can only be used once in a combination. The 900 Series has been installed mainly in light commercial and residential applications.

Easily identifiable, the Simplex 900 Series locks are equipped with five exterior pushbuttons arranged in a circular pattern. The numbers are indicated by roman numerals (I, II, III, IV V) positioned around the pushbuttons on the faceplate. The outside thumbturn, which is used to retract and to extend the latch or bolt, is located either above or below the pushbuttons depending upon the hand of the door.

Rotating the outside thumbturn clockwise retracts the latch or bolt once the correct combination has been entered. 900 Series locks are equipped with a friction clutch mechanism that prevents forced rotation of the outside thumbturn from retracting the latch or bolt. Should the thumbturn be force rotated, it can be returned to the operating position without damaging the lock by turning the thumbturn until it snaps back into place.

When the outside thumbturn is rotated counterclockwise, the combination chamber is cleared and ready for the combination to be entered. If the 900 Series is a deadbolt configuration, rotating the outside thumbturn counterclockwise also extends the bolt. The outside thumbturn is spring-loaded and will turn back to the vertical position once released.

Note: The Simplex1000 and 5000 Series evolved from the 900 Series mechanical pushbutton locks using its mechanical chamber. Although the arrangement of the pushbuttons is different, the pushbutton positions in the 1000/5000 series are vertical, the combination chambers that are the locking mechanisms are programmed using similar instructions.

Changing the known combination of a Simplex 900 Series mechanical pushbutton lock is accomplished with the lock remaining attached to the door.

IMPORTANT: Keep the door open when changing the combination to prevent locking the door.

Step 1 . Turn the outside thumbturn counterclockwise (to the left) until it stops. Then release the thumbturn. This clears any entries from combination chamber.

Turning a deadbolt -equipped 900 Series lock not only clears the combination chamber, but it also extends the bolt. This is why you keep the door open when changing the combination.

Step 2 . Enter the combination. If the combination is unknown, first try the factory default combination. Momentarily press buttons II and IV simultaneously, then momentarily press button III. There should be a slight resistance when each button is pressed. If that does not work because the combination has been changed, see instructions for clearing a lost combination.

Simplex 900 Series locks are equipped with a screw on the top or bottom of the lock housing located on the interior side of the door. Behind this screw is the internal lockout slide that can reset the combination chamber once the correct combination has been entered.

Step 3 . Use the included 1/8” hex wrench and remove the screw.

Step 4 . Slide the long end of the hex wrench into the opening and press the internal lockout slide. There should be a slight click when the slide moves. Do not force the slide to move.

Step 5 . Remove the hex wrench from the lock housing.

Step 6 . Turn the outside thumbturn counterclockwise until it stops, then release.

Step 7 . Enter the new combination. A slight click should be heard when each button is pressed. Remember that each button can only be used once, and two or more buttons can be pressed simultaneously.

Step 8 . Turn the outside thumbturn clockwise until it stops, then release. The new combination has been set.

While keeping the door open, try the new combination at least three times.

Try to retract the latch or bolt just by rotating the outside thumbturn counterclockwise, then clockwise. If the lock unlocks, the combination has been set to a zero code. Repeat steps 3 through 8 to set the desired combination.

Step 9 . Once the new combination operates the lock, install the screw.

Should the combination no longer be available, the only way to reset the combination chamber is by removing the combination chamber from the lock assembly.


Kaba Access Control has determined a new method for decoding an unknown combination. This new method does not require removing the “e” ring and disengaging the unlocking slide. It actually decodes the unknown existing combination. Once decoded, the combination can either be kept or cleared and a new combination can be set.

Step 1 . Remove the Simplex lock from the door by removing the three mounting screws from the interior side of the door

Step 2 . Remove the two screws and flange washers securing the center plate/barrel assembly.

Step 3 . Remove the two screws securing the gear plate from the lock housing.

Step 4 . Remove the two screws and lift the combination chamber from the lock housing.

The combination chamber can now be decoded.

Step 1 . Carefully remove the three-sided dust cover marked Simplex/Kaba Simplex by detaching it from the staked joints at each end of the chamber.

Step 2 . Hold the combination chamber in one hand by the screw tabs on each end with the key stems pointing up with the control shaft at the bottom.

Step 3 . Rotate the control shaft counterclockwise and release to clear the combination chamber.

Step 4 . Look at the locations of the five code gear pockets. If any code gear pocket is at the shearline, it can be ignored as it is in the open position. Look at the code gears whose pockets are not in the open position (shear line).

Step 5 . Find the code gear whose pocket is the farthest away from the open position. If two gear pockets are in similar positions, they were probably pressed at the same time when the combination was originally set.

Step 6 . Depress the key stem(s) that controls the code gear(s) that is the farthest away from the open position. Release the code stem(s). The code gear pocket(s) should move toward the open position. Repeat Step 6 until all of the code gears pockets line up in the open position.

Realigning the code gears takes some practice. If a code gear pocket passes the foot of the unlocking slide, the chamber must be reset and decoding must be started over. A good way to learn is to use a code chamber with a known combination and see how pushing the key stems as if you were entering the combination causes the code gears to move and line up with the pocket aligned to the foot of the unlocking slide.

Once the five code gear pockets are aligned, the new code can be entered.

Step 7 . Depress the lockout slide at the top of the chamber. Release the slide. The lockout slide should remain depressed.

Step 8 . Rotate the control shaft counterclockwise to clear the chamber. The lockout slide should pop out although the button should remain depressed.

With the code gear pockets in the open position and the control shaft clearing the code chamber, a new combination can be entered.

Step 9 . Kaba Access recommends entering the 3 and 5 simultaneously, then entering 4, releasing each key stem after it has been depressed. This is the factory default code of 2 and 4, then 3, if the code was being entered using the pushbuttons.

Step 10 . Once the new combination has been entered, turn the control shaft clockwise. The code change button under the lockout slide should pop up to accept the code.

Step 11 . Reassemble the combination chamber by attaching the three-sided dust cover. Make sure the plate joints on each end slide through the slots in the dust cover. Stake the plate joints to keep the dust cover from disengaging.

The combination chamber is ready to be installed into the lock housing.

Step 12 . Re-assemble the Simplex Lock.

When setting the new combination, follow the above instructions for changing a known combination and use the factory default code combination of 2 and 4 simultaneously, then 3, as the known combination.

The 900 Series Simplex locks are time tested pushbutton locks that can provide mechanical controlled access without having a key.

For more information, contact your local locksmith supplier or Kaba Access Control, Telephone: 336-725-1331. Fax: 336-725-3269. Web Site: .