The Detex 102680 is the OEM cam assembly for the Detex EAX-3500 hardwired timed bypass exit alarm. It's the mechanical component that connects the mortise cylinder to the alarm's arming circuit - when you insert the key and rotate it, the cylinder turns the cam, and the cam's position is what tells the circuit board whether the alarm is armed or disarmed. When the cam strips, cracks, or loses its engagement with the cylinder drive, the key turns freely without changing the alarm state. The unit either stays permanently armed (which triggers false alarms on every door open) or stays permanently disarmed (which defeats the entire purpose of having the alarm there). Either failure mode is a problem. The 102680 cam assembly is the field replacement that restores correct key-operated arming and disarming without replacing the complete EAX-3500 unit.

What the Detex EAX-3500 Is and Why the Cam Matters

The EAX-3500 is Detex's hardwired timed bypass exit device alarm - the commercial-grade step up from the battery-powered EAX-500 and EAX-2500 series. It runs on 24VAC/DC low-voltage hardwired power with a built-in rechargeable backup battery that provides 72 hours of operation during a power outage. The 100dB piezo alarm activates when the monitored door opens without first disarming the unit. The metal enclosure measures 8.13" wide x 8.13" tall x 4" deep and is UL listed and ANSI/BHMA A156.29 certified.

The EAX-3500 ships without a mortise cylinder - that's an intentional design choice. Detex sells it that way so it can be keyed to whatever master key system is already in the building. The mortise cylinder drops into the dedicated cylinder position on the enclosure, and its cam drive engages the 102680 cam assembly inside. One thing worth noting: the EAX-3500 enclosure cover is itself secured by a cam lock. So the cam assembly serves two functions - it's the arming mechanism and it's part of the tamper resistance that keeps unauthorized personnel from opening the enclosure without the key.

Detex Cam Assembly: Arming and Disarming Sequence

The arming and disarming operation on the EAX-3500 works like this. With the door closed, you turn the key counter-clockwise to arm - the cam rotates to the armed position, the circuit board reads that state, the red LED blinks twice and then the green LED holds solid for the default 15-second arming delay, then the unit beeps three times and the green LED goes off to confirm fully armed. Turn the key clockwise to disarm - cam returns to disarmed position, alarm shuts off, green LED signals disarmed state.

The cam has to make positive contact with the circuit board's switch at both endpoints. A worn cam that's not fully seated at the CCW stop may arm intermittently. A cam that won't fully reach the CW stop leaves the alarm in a state where it can't be cleanly disarmed. Both are failure modes the 102680 replacement resolves.

Detex EAX-3500 Exit Alarm: Key Features and Application Context

The EAX-3500's timed bypass is the feature that separates it from simpler exit alarms. A manager can bypass the alarm for a set time window - for deliveries, trash removal, or maintenance access - without disabling the alarm permanently. The unit counts down the bypass window using LED indicators on the front panel and automatically rearms when the door closes, regardless of whether the bypass timer has expired. If the door is left open past the bypass window, the alarm sounds and has to be reset with the key.

The magnetic contact switch that monitors door position can be located up to 50 feet from the enclosure, which matters for large commercial doors or installations where the alarm unit can't be mounted immediately adjacent to the door.