Two signal directions share one piece of hardware in GE's distributed Speedtronic discrete I/O: contact inputs arriving from the plant and relay commands heading back out both terminate on the TDBT board. That double duty is what makes a proven spare worth holding, and this page offers the IS200TDBTH6ABC — base part IS200TDBTH6A at the BC revision — in used condition, cleaned and tested before dispatch.

Isolate the Fault First: Pack, Field Wiring, or Terminal Board?

The order of investigation matters, because the terminal board is statistically the least likely culprit in its own signal chain:

• Start at the field side. Exercise the switch or device, check continuity of the cable run, and measure wetting voltage right at the TDBT terminals. Most dead-input tickets end here.
• Move to the packs. The PDIO I/O packs seated on the board do the scanning, conversion, and Ethernet reporting; reseating or exchanging a pack is a five-minute test that either clears it or convicts it.
• Check the power path. Wetting supplies and pack power feeds take out whole channel groups at once — a failure pattern that passive terminal circuitry can rarely produce on its own.
• Then look at the board. Welded relay contacts after a load-side short, heat-damaged terminals, cracked traces after a lightning event, or persistent hardware/ID alarms pinned to one position are the signatures that genuinely call for a TDBT replacement.

What This Discrete I/O Board Actually Handles

Documented in GE's Mark VIe system hardware guide (GEH-6721), the TDBT is a TMR contact input/output terminal board carrying 24 group-isolated contact inputs — externally wetted at a nominal 24, 48, or 125 V dc, with built-in noise suppression — alongside 12 form-C relay outputs and provision for a relay option card. It mounts on a DIN rail or flat on a sheet-metal assembly, and accepts field wiring (typically #18 AWG) on two terminal banks, relays on the upper block and contact inputs on the lower. Three D-type positions, JR1, JS1, and JT1, accept the PDIO packs; the design assumes redundant packs rather than a single one, which is how the board supports voted I/O across the <R>, <S>, and <T> channels of a TMR system.

How Revision Letters Like BC Fit into the Part Number

Every character in IS200TDBTH6ABC has a role: IS200 marks the Speedtronic board series, TDBT the discrete input/output function, H6A the hardware group and version, and BC the production revision of this particular build. Site drawings often list only the base number; when your label shows more, quote all of it, because matching the revision removes any question about form and fit before the board ships. The conventions behind these fields are explained in our GE Speedtronic Part Number Decoder.

System Context: PDIO Packs and the Discrete I/O Chain

The complete chain runs field device, TDBT terminal board, PDIO Discrete I/O pack, Ethernet network, controller. Around the board itself, GE's guide points to familiar relatives: input conditioning identical to the STCI contact-input board, relay terminal assignments shared with the SRLY relay board, and the WROB option card as the sanctioned way to extend relay functions. Our GE Mark VI IS200 Boards collection holds the neighboring IS200 hardware, the umbrella GE Speedtronic Turbine Control Boards collection spans every generation we stock, and the article Mark V vs Mark VI: DS200 to IS200 is the place to start if your fleet mixes eras.

Building a Complete RFQ for This Board

• The full string from the label — IS200TDBTH6ABC — rather than just the base number
• A label photo, which lets us verify group and revision at a glance
• Turbine model, control system generation, and site wetting voltage class
• Whether a WROB relay option card rides on the position
• Quantity, plus the timeline: unit down now, outage window booked, or shelf stock

How Ordering Works: Quotes, POs, and DDP Delivery

Use the Request a Quote form and expect a response within 24 hours. We accept purchase orders and ship worldwide on DDP terms, meaning duties, taxes, and customs clearance are our problem, not yours. The exact condition and warranty of this specific unit are recorded in the table below.

General Information about the Product
Part Number	IS200TDBTH6A Mark VI IS200
Description	IS200TDBTH6A By GE IS200TDBTH6ABC VIE Controller Card Discrete Terminal Board
Condition	used Clean and Tested. With 1 Year Warranty.