Voted I/O only delivers its promised availability when each redundant path stays independent all the way to the field terminals, and GE built the TDBT terminal board around exactly that principle. The IS200TDBTH8A offered here — a used, cleaned, and tested unit whose label reads IS200TDBTH8APR2 — is the TMR Discrete Input/Output member of the Speedtronic IS200 family, terminating 24 contact inputs and 12 relay outputs for redundant pack service.

Triple Modular Redundancy on the Discrete I/O Layer

The TDBT provides three D-type connector positions — JR1, JS1, and JT1 — each accepting a PDIO Discrete I/O pack with its own Ethernet link to the controllers. In a full TMR system the packs serve the <R>, <S>, and <T> cores, so a single pack or network failure never blinds the logic to a field contact; GE's documentation also describes dual-controller layouts in which JR1 networks to <R>, JS1 to <S>, and the JT1 pack reports to both. What the board explicitly does not support is operation from one lone pack. On the field side there are 24 group-isolated contact inputs scaled for 24, 48, or 125 V dc external wetting, protected by noise suppression against surge and high-frequency interference, and 12 form-C relay outputs that can be extended with an option card.

Fault-Finding Guide: When the TDBT Is Innocent

• One core disagrees with the other two on an input. That points at the pack, cable, or connector of the disagreeing channel — the field signal is common to all three, so a genuine field event shows up on every core.
• All cores read the same wrong state. Now suspect the field device, its wiring, or the wetting voltage; a terminal board rarely corrupts a signal identically for three independent packs.
• Relay output misbehaving. The relays physically live on the terminal board, so verify the command path first, then inspect the relay and its load circuit — a field short can weld contacts, and that is the most common true board failure we see.
• Diagnostic or hardware alarms fixed to the board position. Once packs have been swapped to rule them out, an alarm that refuses to move justifies replacing the TDBT.

Running that sequence before ordering prevents the classic outcome: a healthy terminal board gets replaced while the actual fault — a pack or a wetting supply — rides along into the next shift.

Making Sense of IS200TDBTH8A and the PR2 Marking

The structured part of the number reads IS200 (Speedtronic board series) + TDBT (Discrete Input/Output terminal board) + H8A (hardware group and version). This unit's label additionally shows PR2. We have not located a published GE breakdown of that marking, so we treat it the way we recommend you do: photograph the label, quote the entire string, and match it — guessing at suffix meanings is how the wrong board ends up in a cabinet. The documented numbering conventions are summarized in our GE Speedtronic Part Number Decoder.

Companion Hardware in the Discrete Signal Path

GE's guide ties TDBT to a small ecosystem: signal conditioning borrowed from the STCI contact-input terminal board, relay terminal assignments shared with the SRLY relay board, the WROB relay option card (WROBH1 carries six per-relay jumpers for dry-contact versus power-distribution duty), and the PDIO packs that carry everything to the controllers. Explore the surrounding hardware in GE Mark VI IS200 Boards and the complete range in GE Speedtronic Turbine Control Boards; readers comparing platforms will find Mark V vs Mark VI: DS200 to IS200 a useful primer on how GE's board families evolved.

Your Quote Request: What to Attach

• Every character on the label — for this unit, IS200TDBTH8APR2
• A photo of the nameplate or barcode label
• Turbine model, control platform, and whether the position runs full TMR or dual-controller
• Wetting voltage class and any option card fitted
• Quantity and required delivery timeframe

From RFQ to Delivered Board

Hit Request a Quote and our team replies within 24 hours with availability and lead time. Every shipment travels DDP to destinations worldwide — no customs surprises on your side — and we work from purchase orders issued by plants, OEMs, and service companies alike. The condition and warranty covering this specific board appear in the table below.

General Information about the Product
Part Number	IS200TDBTH8A Mark VI IS200
Description	IS200TDBTH8A By General Electric IS200TDBTH8APR2 TMR Contact I/O Terminal Board
Condition	used Cleaned and Tested. With 1 Year Warranty.