What the IS200VAICH1B Analog Input Card Does

The IS200VAICH1B is a VME Analog Input/Output (VAIC) card that lives inside the VME rack of a GE Speedtronic Mark VI turbine controller, not out at the field wiring. In its standard configuration the card handles 20 analog inputs and 4 analog outputs, with signal conditioning, an analog multiplexer, an A/D converter, and a D/A converter on board. Field transducers never wire directly to the VAIC — they land on a companion terminal board (TBAI, or an older DTAI), which then connects to the VAIC over a ribbon/cable link into the rack. The card digitizes each input and pushes the values across the VME backplane to the VCMI communications card, which hands them to the controller.

Simplex vs. TMR: Why There May Be Two or Three of These in a Panel

VAIC supports both simplex and Triple Modular Redundant (TMR) architectures. In a TMR panel, the same terminal board fans its input signals out to three VME racks (R, S, and T), each with its own VAIC. Outputs are produced by all three cards simultaneously and voted — if one VAIC fails, the remaining two keep producing the correct current with no bump to the process. That's the main reason a turbine with a TMR Mark VI panel needs its VAIC boards replaced as a matched set consideration, not necessarily as a single spare: know whether your panel is simplex or TMR before you order.

Before You Buy a Replacement, Diagnose It

A pegged or frozen analog reading is the single most common reason a VAIC gets pulled — and it's frequently not the card. Work through this order first:

• Check the terminal board (TBAI/DTAI) and field wiring first. An open transducer, a blown fuse on the terminal board, or a loose field connection produces exactly the same symptom as a bad input channel on the VAIC.
• Know the difference between a hardware limit fault and a system limit fault. Hardware limit checking uses fixed, non-configurable high/low thresholds — if a channel exceeds them, that input simply stops being scanned. System limit checking uses configurable alarm thresholds set up in the application. A tripped system limit is usually a process or configuration issue, not a card failure.
• On TMR panels, a single-channel voting deviation often points at the field signal, not the card. If one of the three VAICs disagrees with the voted median beyond the configured limit, it flags that channel — check the transducer and wiring on that leg before swapping the board.
• A "hardware incompatibility" fault usually means a terminal-board mismatch, not a dead card. The terminal board carries its own ID chip (serial number, board type, revision, connector location) that the VAIC reads on startup. Pairing the wrong terminal board revision with the wrong VAIC generation throws this fault even though both boards are healthy.
• Rule out the obvious mechanical causes. Reseat the board with rack power removed, check the captive screws are tightened, and confirm the RUN LED is flashing green rather than solid red (FAIL) or showing steady orange (STATUS/diagnostic alarm).

Reading the IS200VAICH1B Part Number

Breaking down IS200VAICH1B IS200VAICH1BBB: IS200 identifies the Mark VI-era Speedtronic numbering system, VAIC is the functional board type, H is the surface-mount technology code, and the digits/letters that follow (1, B, BB) track assembly variant and revision history. VAIC has gone through two generations that matter for compatibility. The original generation — everything through H1C, including this H1B — pairs with terminal board TBAIH1B or earlier, or any revision of DTAI, and supports up to 500 Ω of loop load on a 20 mA output over 1,000 ft of #18 wire. The newer H1D generation supports higher loop loads (up to 800 Ω with the same wire run) and needs TBAIH1C or later, or any STAI terminal board. Always match the full suffix printed on the label — don't assume two boards are interchangeable just because both start with IS200VAICH1.

For the full logic behind every character in a Mark VI part number, see our GE Speedtronic part number decoder.

Related Cards and Terminal Boards

If you're sourcing for a VAIC, you'll typically also be dealing with: TBAI (the standard analog input terminal board), DTAI and STAI (earlier and later terminal board families), and VCMI (the VME communications card that moves VAIC data to the controller). If your site is still running Mark V DS200-era hardware alongside Mark VI equipment, our DS200 to IS200 migration guide covers how the two generations map to each other.

What to Include in Your RFQ

• Full part number exactly as printed, including suffix (e.g., IS200VAICH1BBB) and revision letters
• A photo of the board label if you're unsure of the exact revision
• Turbine model and Mark VI panel configuration (simplex or TMR)
• Quantity needed and how urgent the requirement is (unit down vs. spare stock)

Request a Quote

Alo Tech Parts sources and tests GE Speedtronic Mark VI boards for maintenance teams worldwide. This listing is not sold at checkout — submit a Request a Quote with your part number and urgency and our team responds within 24 hours with availability, lead time, and DDP pricing to your site. We ship worldwide and accept purchase orders.