Platform service
Elwin Security repairs and replaces Mircom TX3 telephone entry and Touch Screen intercoms at Bay Area multifamily and commercial properties. That covers the TX3-120 and TX3-2000 lobby control units, 15- and 22-inch Touch Screens, the TX3-T10, and door-strike and relay wiring.
Use case
Each situation below points to a different part of the system.
Mircom's TX3 telephone access manual (LT-969, version 7, March 2023) powers each lobby control unit from a PS-4P plug-in transformer rated 16 VAC, 40 VA, and puts the maximum draw of an 8-line unit at 6.2 watts. Mircom's FAQ attributes a blank display with the backlight on to poor grounding and asks for a chassis ground under 50 ohms. Elwin tests the transformer and the ground before it replaces a board.
Mircom's FAQ answers a boot sequence that stops at 30 percent with a UPS on the building feed and a new CFast card, and answers a blue screen with a new CFast card. For a 22-inch screen that keeps going black, the same FAQ points to input voltage below the required 24 VDC, a reversed 120 VAC feed or a damaged power module. The Touch manual (LT-996, version 17, August 2023) states that a UPS is not required on Touch Screens running Windows 10.
Mircom's FAQ says the dry SPDT relay contacts in TX3-series panels can wear with time and that the corrective action is to change the relay. LT-969 requires a separate transformer for the door strike and limits the strike supply to 28 VAC at 1 A or 30 VDC at 1 A. Where a TX3 relay releases a maglock or an exit door, the fire marshal or local AHJ decides what egress hardware is acceptable.
Service focus
Mircom publishes replacement-part instructions, model-number bulletins and a product warranty, so the first job is to identify the model suffix, the boards fitted and the software version before quoting.
For lobby units, Mircom publishes the RB-MD-1398-2000-256 main controller board (LT-6636-256, March 2022), the RPL-MD-1244 microphone kit and the RPL-LK-Y1211 lock. For Touch Screens it publishes the RPL-SC-420005 22-inch display for -E and -F models, the RPL-SC-420009 15-inch display for -E models, and the RPL-TX3-CF32W10-15D, -15WR and -22D CFast kits. For the weather-resistant units it publishes the RPL-LK-WR lockset, the RPL-SC-420002 display and the RPL-TOUCH-WR-WK window kit, and Elwin repairs with the Mircom part that matches the model.
A TX3 panel dials over a dedicated telephone line (ADC) or over the building's existing suite lines through a TX3-NSL-8M relay cabinet (NSL), with up to five lines on one panel and no support for non-configurable PBX systems. Where the phone line itself is the problem, Mircom's MiVoIP service with a TX3-ATA adapter replaces it under a MiConnect subscription.
Mircom's 2021 and 2022 bulletins discontinued the -D 22-inch Touch Screens in favor of -E models with a new screen. When a board upgrade does not fit, Elwin replaces the panel with a TX3-T10 or another video intercom.
Service check
A model name on the faceplate is not enough. The board set, the suffix, the Windows version and the line type decide which Mircom part, bulletin or path applies.
Lobby unit or Touch Screen; the -B to -F suffix or a -256 suffix; the boards fitted. Mircom's LT-6694 identifies -B, -C and -D Touch Screens by the MD-1062 or MD-1346 PC board, the MD-1086 or MD-1245 lobby controller and the MD-1105 or MD-1236 audio mixer board.
PS-4P transformer on a lobby unit or TX3-PS24-5A on a Touch Screen; voltage at the panel; chassis ground.
Dedicated ADC line or NSL relay cabinet; the separate IP-256 module on TX3-256 models; RS-485 wiring.
Scope details
The faceplate is what visitors see. The controller board, the storage card, the phone line, the relays and the software version are what a repair touches.
Mircom's Touch Screen category lists the TX3-TOUCH-F15-E, S15-E, F22-F, S22-F, S15B-WR-A and S15S-WR-A, and LT-996 covers the earlier -C and -D versions of each size. The current datasheets specify an Intel E3940 processor, a 32 GB mSATA SSD, Windows 10 IoT with SQL Server Express, and a TX3-PS24-5A 24 V, 156 W switching power supply. The indoor S15-E display is rated 300 nits and 0 to 50°C; the weather-resistant WR-A is rated 1600 nits and -20°C to 50°C.
Where a TX3 relay releases a maglock or an exit door, the fire marshal or local AHJ decides what egress hardware is acceptable.
Its May 11, 2026 bulletin added TX3-T10 support to MiVision, which needs a TX3-Cloud-Gateway on site and a subscription. MiVoIP needs a TX3-ATA adapter and a MiConnect subscription.
Process
Repair decisions follow Mircom's published manuals, bulletins and part instructions.
Record the model, suffix, boards, software version, line type and relay wiring, then test power, dial-out, directory, keypad or touch, and release at the panel. Mircom's FAQ ties an 'error 0' with no dial-out to a short on the RS-485 lines or the on-board camera supply.
Result: The quote names the exact Mircom board, part, line fix or replacement, not a generic intercom repair.
Match the fault to Mircom's replacement-part instructions, its -256 and model-number bulletins, its warranty terms, or a TX3-T10 or other replacement panel.
Result: The property knows what the fix costs and what it leaves in place.
Fit the part or the new panel, and restore the line, power and relay path.
Result: The entry works and the property can manage its own directory.
Field proof
Mircom's published documents cover installation manuals, part instructions, bulletins and warranty terms.
Mircom's product warranty covers the hardware component of products manufactured exclusively by Mircom against defects in materials and workmanship for three years, and its exclusions include excessive voltage, overheating from sunlight, improper repair and telephone line failures.
Mircom's FAQ states that a unit damaged by a power spike or an unregulated 120 VAC supply is not under warranty, and that a return goes back through the distributor with a Mircom case number attached.
Mircom's remedy under its warranty is, at its option, repair or replacement of the goods or a refund of the purchase price. Its August 11, 2021 purchase terms require a written warranty claim within 30 days after the defect should reasonably have become apparent.
Mircom publishes field instructions for replacing a Touch Screen's display, speakers and CFast card, and a lobby unit's door and main controller board.
The TX3-T10 manual (LT-6766, December 2025) says the TX3-T10BB backbox is required and failure to install it will void the warranty.
Mircom's bulletins discontinued the TX3-TOUCH-F22-D (September 21, 2021) and TX3-TOUCH-S22-D (June 15, 2022) in its price book and replaced each with an -E model carrying a new 22-inch screen, because the previous screen became obsolete.
Service request
Tell Elwin what is not working, what systems are already on site, and which access points matter most. The next step is a scope grounded in the building, not a generic product list.
