Where DS200TCDAG1BDB Sits in a Mark V System

When a Mark V panel throws a contact-input or relay-output fault, the board doing that work is the TCDA – and DS200TCDAG1BDB is a G1-group version of it. The card's job is to translate field-level signals (limit switches, permissives, status contacts) into the control logic, and to drive relay outputs to contactors, solenoids, and annunciator circuits on the other side. Software configuration, not hardware wiring on the card, decides what each point does.

You'll find the TCDA mounted in one of the Mark V's control cores: <R>, <S>, or <T> in a TMR (triple redundant) panel, or the single core of a Simplex system. TCDA cards are also part of the documented card set in the <C> communication core on many installations. In the rack, it works with a companion relay board (TCRA) and with I/O cards such as TCQA, TCQE, and TCEA over the panel's IONET.

Before You Order: Confirm the TCDA Is Really the Fault

Maintenance teams frequently order a new TCDA and find the fault is unchanged – because the real cause was somewhere else. Documented Mark V cases point to several look-alike causes:

• TCEA termination jumpers set wrong. The IONET should loop through all TCEA cards in the core and terminate only at the TCDA; if a TCEA has its termination resistor IN instead of OUT, you'll see the same continuous state-cycling fault as a bad TCDA.
• Power supply issues on the TCPS card feeding the core rather than the TCDA itself – check the rails before swapping the card.
• Electrical noise on the control bus, including ripple or spikes from a battery charger or from de-energizing unsuppressed DC coils nearby.
• A firmware/PROM mismatch. GE has documented IONET communication issues that were resolved with a PROM upgrade rather than swapping hardware.
• Loose seating or a corroded connector pin on the card or its ribbon cable.

It's also worth distinguishing the TCDA from the TCRA relay card it pairs with. TCRA carries electromechanical relays that wear with switching cycles; the TCDA doesn't share that mechanism. If the complaint is a relay output that won't pick up, look at the TCRA first. There is no fixed service life for a TCDA – many stay in service eight-plus years without trouble, and Mark V cards generally have a mean time between failures in the low hundreds of thousands of hours according to published industry experience, with cabinet heat, humidity, dust, and voltage transients being the more common drivers of an actual failure than age by itself.

Understanding the DS200TCDAG1BDB Part Number

DS200 marks the Mark V-era board series, TCDA identifies the Digital I/O function, G1 is the product grouping, and BDB is this card's specific revision combination (functional and artwork revisions on top of the base G1 design). G1 and H1 TCDA boards are distinct hardware groupings under the same acronym, not simply older and newer versions of one another – do not assume cross-compatibility without checking your documentation. Quote and order using the complete string, DS200TCDAG1BDB, rather than a partial number.

Related Boards and the Path to Mark VI

The TCDA typically shows up in the same conversations as TCRA, TCQA, TCQE, TCEA, STCA, and UCPB. For plants weighing a platform upgrade, GE's Mark VI replaced the DS200 series with IS200-series boards on a different I/O architecture; see our Mark V vs Mark VI: DS200 to IS200 guide for the general picture. For the mechanics of GE's part-numbering system, see the GE Speedtronic Part Number Decoder, and for how TCDA compares with other DS200 boards, see GE Mark V DS200 Boards Explained.

What to Send Us for a Quote

• The full part number and suffix, e.g., DS200TCDAG1BDB
• A photo of the physical label if you can get one
• Turbine model and panel configuration (Simplex or TMR)
• Quantity
• Urgency – is the unit down now, or is this for planning

Request a Quote

This DS200TCDAG1BDB is offered used, clean and tested, with a 1-year warranty (details below). Pricing isn't published online since Mark V board quotes depend on exact revision match and current stock – send a Request a Quote and expect a response within 24 hours. Alotechparts.com ships worldwide DDP, accepts purchase orders, and handles both planned outages and urgent turbine-down orders.

General Information about the Product
Part Number	DS200TCDAG1B
Description	GE DS200TCDAG1B DS200TCDAG1BDB Digital I/O Board Mark V
Condition	used Clean and Tested. With 1 Year Warranty.