When a Detex EAX-3500 exit alarm stops responding correctly to door events, the logic board is almost always where the diagnosis begins. The Detex 106392 Logic Board is the printed wiring assembly (PWA) that handles all the control functions inside the EAX-3500, from reading the magnetic switch input to managing the timed bypass sequence to triggering the 100-decibel alarm when an unauthorized exit is detected. If the alarm won't sound, the bypass timer isn't working right, or the unit has been acting up since a power issue, the logic board is where you start.

What the Logic Board Controls in the EAX-3500

The EAX-3500 is a hardwired, timed-bypass exit alarm with a rechargeable backup battery designed for commercial and institutional door applications where unauthorized access is a genuine concern. It runs on 12 to 24VAC with a rechargeable 6V battery backup that provides up to 72 hours of continued operation during a power outage.

The 106392 logic board sits inside the enclosure and serves as the brain of the entire assembly. It receives the magnetic switch signal when the door opens, controls the bypass timer when a manager authorizes a temporary opening for deliveries or trash removal, manages the automatic re-arming after the door closes, and interfaces with the power board through the dedicated wiring harness. Without a functioning logic board, none of those operations work as intended. The alarm either won't sound, won't bypass, or won't re-arm, which defeats the entire purpose of having the device installed.

Companion Parts to Know Before You Order

If you're troubleshooting an EAX-3500, it helps to know the full parts breakdown before pulling the unit apart. The 106392 logic board works alongside the 106390 power board, connected by the 106385 wiring harness. The reset switch assembly is part number 103990, and the add-time switch assembly is 106740. If the board damage is extensive or the unit has been running for many years, Detex also offers the 106383 S&R EAX-3500 board replacement kit as a more complete repair option.

Knowing which part is actually at fault saves you the cost of replacing components that are still working. If the alarm responds to door events but the bypass timer isn't counting down correctly, the logic board is your answer. If the unit isn't powering up at all, start with the power board and transformer before replacing the logic board.

The full EAX-3500 parts diagram and wiring instructions are available as a free download in our price books and catalogs section. Worth grabbing before you start the repair so you've got the complete assembly reference in front of you.

Where the EAX-3500 Is Typically Installed

The EAX-3500 is one of Detex's more capable exit alarm units because of its timed bypass feature and hardwired power with battery backup. You'll find it on rear service doors, loading dock entries, emergency stairwell exits, and secondary building access points in retail stores, warehouses, schools, and multi-tenant commercial buildings. These are high-stakes locations where an alarm that stops working creates a real security gap, which is why getting the right replacement part quickly matters. Our exit alarms catalog and broader exit devices section carry parts across the full Detex alarm lineup if you're sourcing for multiple units on the same job.

Same-day shipping goes out on anything we have in stock, and orders over $450 ship free. Got a multi-unit project or need help confirming the right part? Call us at 845-935-0301 or email sales@securityparts.com. Check our shipping and returns policy before you order, or browse the complete parts catalog to pull everything you need in a single order.