Twenty-four contact inputs and twelve relay outputs on one mounting plate: that is the working definition of the IS200TDBTH4A, a GE Speedtronic Discrete Input/Output (TDBT) terminal board. The board on this page is the IS200TDBTH4AAA build — base number IS200TDBTH4A at the AA revision — supplied as new surplus in open-box condition. In service it is where discrete field wiring physically enters the control system's redundant I/O chain, in both directions.
One Terminal Board, Two Jobs: Contact Inputs and Relay Outputs
GE documents TDBT as a TMR contact input/output terminal board that mounts flat or on a DIN rail. The input side provides 24 group-isolated contact inputs running on externally supplied wetting voltage, filtered against surge and high-frequency noise; the output side switches 12 form-C relays. AX Control's published breakdown for the TDBTH4A group describes a nominal 48 V dc floating wetting arrangement with a 32 to 64 V dc operating window — verify that against your site drawings before ordering, because the TDBT family as a whole spans 24, 48, and 125 V dc wetting classes and the hardware group must match. In Mark VIe service the board hosts PDIO I/O packs on its JR1, JS1, and JT1 D-type connectors, each communicating with the controllers over Ethernet, and GE's guidance is that TDBT is not intended to run from a single pack.
Troubleshooting Checklist Before Ordering a TDBTH4A
Most discrete I/O complaints resolve upstream or downstream of the terminal board. Run these checks first:
- Measure wetting voltage at the suspect input terminals. No voltage means a supply or distribution problem, not a board problem.
- Operate the field device manually and watch the point in the control system. If the state changes, the channel is healthy.
- Swap or reseat the PDIO pack on the affected connector position. Diagnostics that move with the pack exonerate the terminal board.
- For a stuck relay output, confirm the command is actually reaching the board, then listen for the relay transition. A welded contact after a field-side short is a real board failure — and the reason the load circuit should be inspected before the replacement goes in, or the new board inherits the same fate.
- Check terminal screws and lugs for looseness or corrosion before condemning electronics; intermittent points usually live there.
IS200TDBTH4A vs IS200TDBTH4AAA: How the Suffix Works
IS200 identifies the Speedtronic board series, TDBT the discrete input/output function, and H4A the hardware group and version. The extra letters in IS200TDBTH4AAA are the production revision of this particular build. When ordering, quote the longest string printed on your label: the base number establishes fit and function, and the revision letters let us match your unit or advise on what we can supply against it. The full numbering logic is laid out in our GE Speedtronic Part Number Decoder.
Option Cards and Companion Hardware
TDBT accepts a WROB relay option card for expanded relay functionality — and AX Control's documentation specifically cautions that the WROF and WROG option boards are not interchangeable with it. Input signal conditioning parallels the STCI contact-input board, and relay terminal assignments follow the SRLY relay board, which helps when transposing point lists between board types. The service-side mate is the PDIO Discrete I/O pack. Related hardware is grouped in GE Mark VI IS200 Boards and across generations in GE Speedtronic Turbine Control Boards; for how the IS200 era relates to earlier DS200 hardware, read Mark V vs Mark VI: DS200 to IS200.
Details That Make Your RFQ Faster
- Full part number with revision letters (IS200TDBTH4AAA here) exactly as printed on the label
- A label photo, if the installed board is accessible
- Turbine frame and control system generation, plus the wetting voltage class used at your site
- Presence and part number of any relay option card on JW1/JW2
- Quantity and urgency — forced outage, planned work, or stock replenishment
Open-Box Availability and 24-Hour Quotes
This TDBTH4A is new surplus that left its original factory carton but was never placed in service; the precise condition and warranty wording appears in the table below. Click Request a Quote with your details and you will have an answer within 24 hours. We deliver worldwide under DDP terms, with customs cleared before the box reaches your dock, and we accept purchase orders — so procurement can move as fast as the outage schedule demands.
General Information about the Product |
Part Number |
IS200TDBTH4A Mark VI IS200 |
Description |
GE General Electric IS200TDBTH4A IS200TDBTH4AAA Contact Relay Board OPEN BOX |
Condition |
newSurplusNoBox New Surplus Open Box. 1 Year Warranty. |
