SentrySafe SF123ES - User Manual

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Inside the Sentry Digital Firesafe

Introduction

This paper describes and illustrates the construction and operation of a Sentry brand safe that was

purchased in 2003/4. This small safe opens using a key and a code entered on a digital keypad. This paper

is not a replacement for the instruction manual, but is information designed to help in understanding the

operation and in maintaining the unit. This information is provided for your use only, with the

understanding that there is no warranty that this information is complete or accurate. All work done on the

safe by you is at your risk, and may void any warranty.

Operation

The safe door is secured by six deadbolt latches that engage between the door and the safe, two on each

side, and one each on top and bottom. Here’s what is hidden inside the door: The six latches are geared

together via a wheel gear that operated by the entry handle. Two interlocks prevent opening the door -- a

key operated pin block and a solenoid operated by the electronic combination. When the door is open,

another mechanical latch interlock holds the door latches retracted. (See photos at the end of this paper

showing all items located inside the door.)

To open the door, insert the key, turn CW and pull out the cylinder, thus withdrawing the pin block inside

the door. This removes one of the blocks on the door mechanism. Remove the key if desired. If the key

mechanism is pushed in (key or no key), the cylinder latches "IN" and activates the pin block.

To remove the second interlock (the solenoid), enter the combination code. When correctly entered, the

electronics causes the solenoid to operate, withdrawing the solenoid block on the door mechanism. If the

door is not opened in about five seconds, the solenoid releases, and the combination must be reentered.

(NOTE: low batteries or bad battery contacts can interfere with this step. Be sure your batteries are fresh.)

At this point, the handle can be turned down (CCW) which rotates the interior wheel, which via rack and

pinions withdraws the six door latches allowing the door to open. If the door is fully opened while the

handle is down, a simple leaf spring presses the lower right door latch (lower left, interior) toward the front,

and the latch arm drops over a slight ledge where it is help by the spring. This prevents the handle from

rising and the door latches from springing back to their outward engaged positions. When the door is

closed, a plastic pin then presses inward on the door, lifting the latch support, and releasing the latch,

allowing all latches to engage and the handle to rise.

Access to the door mechanisms

When the door is opened, the inside of the door is a plastic panel with key hangers and an envelope slot.

The plastic panel is a pain to remove. First, operate the lock to retract the door latches as far as possible.

Facing the back of the door, along the left inner edge you will find two plastic dimples. Press the upper left

one inward, and insert a putty knife between the door and panel and pry the panel gently around the upper

door latch and the plastic dimple. Do the same at the lower left. Then pry the bottom of the panel around

the bottom door latch. Move up the right side of the panel. Here there are no dimples showing, but they

are present inside, so you will pry the panel past them. Finally, do the top of the panel.

As you remove the panel, go slow, be careful: the panel has projections that hold various of the mechanism

parts in place. When you move the mechanism or touch things, be careful not to disturb their positions or

remove parts until you have figured out how it works.

Maintenance

• Check that there are no burrs on the solenoid plunger that would cause it to stick in either position

and that it works smoothly.

• Oil the key and housing so that it operates smoothly

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Summary

Introduction to Sentry Digital Firesafe

Operation of Sentry Digital Firesafe

This document describes the construction, operation, and maintenance of a Sentry brand safe, specifically a model purchased around 2003/2004. The safe is designed to provide secure storage, opening via a combination of a physical key and a digital keypad code. It's intended to help users understand how the safe works and how to maintain it, rather than serving as a replacement for the official instruction manual.

Function Description

The primary function of the safe is to secure its contents. This is achieved through a robust locking mechanism involving six deadbolt latches. These latches are strategically positioned, with two on each side, and one each on the top and bottom of the door, engaging with the safe body. The entire latch system is interconnected through a wheel gear, which is operated by the safe's external handle.

To ensure a high level of security, the safe incorporates two distinct interlock mechanisms that prevent the door from being opened even if the handle is turned. The first interlock is a key-operated pin block. This mechanical block physically obstructs the door mechanism, preventing the latches from retracting. The second interlock is a solenoid, which is an electromagnetically controlled block. This solenoid is activated by the electronic combination entered on the digital keypad. Both of these interlocks must be disengaged for the door to be opened.

Once the door is successfully opened, an additional mechanical latch interlock engages. This mechanism holds the door latches in their retracted position. This feature is crucial because it prevents the latches from accidentally extending while the door is open, which could potentially cause damage or make it difficult to close the door later. This interlock is typically a simple leaf spring mechanism that presses against a specific latch, holding it in place until the door is closed. When the door is closed, a plastic pin presses inward, releasing this interlock and allowing the latches to extend and secure the door.

Usage Features

Operating the safe involves a sequence of steps that combine mechanical and electronic actions.

To open the safe:

Key Operation: The first step is to use the physical key. Insert the key into the cylinder, turn it clockwise, and then pull the cylinder outwards. This action withdraws the internal pin block, which is one of the two interlocks. Once the pin block is withdrawn, the key can be removed if desired. It's important to note that if the key mechanism is pushed back in (with or without the key), the cylinder will latch "IN," reactivating the pin block.
Combination Entry: The second step involves disengaging the solenoid interlock. This is done by entering the correct combination code on the digital keypad. Upon successful entry, the electronic system will activate the solenoid, causing it to withdraw its block from the door mechanism. A critical timing aspect here is that if the door is not opened within approximately five seconds after the solenoid is activated, the solenoid will release, and the combination will need to be re-entered. This feature adds an extra layer of security and prevents the safe from remaining unlocked indefinitely after a combination entry.
Handle Operation: With both the key-operated pin block and the solenoid block disengaged, the safe is ready to be opened. The handle can then be turned downwards (counter-clockwise). This action rotates the internal wheel gear, which in turn, through a system of rack and pinions, retracts all six door latches, allowing the door to swing open.

When the door is fully opened and the handle is in the down position, a specific mechanism engages to keep the latches retracted. A leaf spring presses against the lower right door latch (when viewed from the interior), causing it to move forward slightly. This latch arm then drops over a small ledge, where it is held by the spring. This prevents the handle from rising and the door latches from springing back to their extended, engaged positions.

To close the safe:

Closing the Door: Simply swing the door shut.
Latch Engagement: As the door closes, a plastic pin on the safe body presses inward on the door, lifting the latch support that was holding the latches retracted. This releases the latches, allowing them to extend and engage with the safe frame. Simultaneously, the handle will rise back to its original position, indicating that the door is secured.

Accessing the internal mechanisms of the door, for maintenance or inspection, requires careful removal of the plastic inner panel. This panel is secured by several plastic dimples and projections. To remove it:

Retract Latches: First, operate the lock to retract the door latches as far as possible.
Left Side Removal: Facing the back of the door, locate two plastic dimples along the left inner edge. Press the upper left dimple inward, and carefully insert a putty knife between the door and the panel. Gently pry the panel around the upper door latch and the dimple. Repeat this process for the lower left dimple.
Bottom and Right Side Removal: Next, pry the bottom of the panel around the bottom door latch. Then, move up the right side of the panel. Although no dimples are visible externally on the right side, they are present internally, so gentle prying will be necessary to release the panel past them.
Top Side Removal: Finally, pry the top of the panel to fully release it.

It is crucial to proceed slowly and carefully when removing the panel, as it has projections that hold various mechanism parts in place. Disturbing these parts or removing them without understanding their function can lead to operational issues.

Maintenance Features

Regular maintenance is essential to ensure the safe operates smoothly and reliably. Several key areas require attention:

Solenoid Plunger Inspection: Periodically check the solenoid plunger for any burrs. Burrs can cause the plunger to stick in either its extended or retracted position, preventing the solenoid from operating correctly. If burrs are found, they should be filed or sanded smooth to ensure the plunger moves freely.
Key and Housing Lubrication: The key mechanism and its housing should be oiled regularly. This lubrication ensures that the key operates smoothly, making it easy to insert, turn, and withdraw, and preventing any sticking or stiffness.
Withdraw Block Inspection: Similar to the solenoid plunger, the edges of the "Withdraw block" (likely referring to the key-operated pin block) should be checked for burrs. Any burrs found should be filed or sanded as needed to ensure smooth operation and prevent it from catching or sticking.
Battery and Terminal Cleaning: The safe's electronic components rely on battery power. It is important to regularly inspect the battery or battery holder terminals for dirt or corrosion. These can interfere with electrical contact and lead to intermittent or complete failure of the electronic lock. Cleaning the terminals with a suitable cleaner, such as tuner cleaner from a reputable electronics store, can resolve these issues. A key indicator of low battery power or poor connections is if the green LED on the keypad dims significantly immediately after the combination is entered and the solenoid is energized. This suggests that the batteries are weak or there are bad connections, and fresh batteries should be installed.

The document also mentions a repair scenario where the safe's handle broke off during a robbery attempt. This highlights the importance of understanding the safe's construction for potential repairs. In this specific case, the handle was repaired by drilling several 1/8" holes into both the handle and its stub, roughing both surfaces, and then liberally applying PC7 epoxy to the pins and joint, allowing it to cure completely. This demonstrates that with proper knowledge and tools, certain mechanical repairs can be undertaken to restore the safe's functionality.