Siemens TMBA-4 S30810-Q430-X PBX Trunk Card 42013 MFG 01717 Hicom EWSD

Siemens TMBA-4 S30810-Q430-X PBX Trunk Card 42013 MFG 01717 Hicom EWSD

The Siemens TMBA-4 is a 4-channel trunk interface card designed for use in Siemens PBX and enterprise telephone switching systems, including the Hicom and EWSD product families. Identified by part number S30810-Q430-X, this card plugs into the PBX chassis backplane and provides trunk-side connectivity for the switching system. It features four trunk channels indicated by labeled red LED status indicators (TC0, TC2, TC4, TC6) on the front bracket, allowing technicians to monitor individual trunk states at a glance.

Specifications & What's Included

• Model: TMBA-4
• Part Number: S30810-Q430-X
• Secondary Reference: 42013 MFG 01717
• Form Factor: Card / Module (backplane-mounted)
• Number of Trunk Channels: 4
• LED Indicators: TC0, TC2, TC4, TC6 (4 red LEDs on front bracket)
• Relay: GI Clare HGRM 51111N00 mercury-wetted contact relay (visible on PCB)
• Onboard Transformers: Multiple small signal transformers visible on component side
• Logic ICs: Mullard and SN74LS-series TTL logic ICs present on board
• PCB Edge Connector: Gold-finger backplane connector for chassis installation
• Compatible With: Siemens Hicom and EWSD PBX systems
• Item Includes: Card only

Applications

The TMBA-4 is a trunk module board for Siemens enterprise PBX switching platforms, primarily the Hicom series (including Hicom 150, 300, and related derivatives) and the EWSD digital switching system. Trunk interface cards like this one sit between the PBX switching matrix and the external telephone network, terminating analog or digital trunk lines and converting signaling for internal processing. The mercury-wetted contact relays on this board are characteristic of telecom-grade switching circuits where low contact resistance and long relay life are required for reliable line supervision and ringing detection. These types of cards were widely deployed in corporate, campus, and institutional PBX environments throughout the 1980s and 1990s, and replacement and spare boards remain in demand for maintaining legacy Siemens switching installations that are still in service. Technicians maintaining or expanding existing Siemens Hicom or EWSD systems are the primary buyers for this type of module.