Description
Key Technical Specifications
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Model Number: IS200TFBAH1ABA
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Manufacturer: General Electric
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Logic Voltage: +5 V @ 1 A, ±12 V @ 150 mA from VME back-plane
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Analog Inputs: 12 differential, ±10 V or 4-20 mA, 12-bit resolution, 5 kHz bandwidth
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Analog Outputs: 4 isolated, ±10 V, 5 mA drive, short-circuit protected
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Discrete I/O: 16 opto-isolated 24 V inputs, 8 relay outputs (Form-C, 2 A)
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Connectors: 96-pin DIN to VME, two 20-position pluggable for field cables
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Isolation: 1500 Vrms channel-to-logic, 500 V channel-to-channel
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Diagnostics: Green “BOARD OK,” red “FAULT” LEDs visible through bezel
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Operating Temperature: –20 °C to +70 °C (conformal-coated)
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Dimensions: 17.8 cm × 33.0 cm, single-slot 6U VME
IS200AEADH1ABA
Field Application & Problem Solved
In a 2000-frame-7 combined-cycle block the Mark VI doesn’t read raw LVDTs—it wants clean, isolated ±10 V signals that represent servo position, speed bias, and exhaust temperature. The IS200TFBAH1ABA is the card that does the scaling. It sits in the VME rack, reads 4-20 mA from dual LVDTs, ±10 V from magnetic pickups, and thermocouple millivolts from the exhaust rake, then dumps the data onto the VME bus every 10 ms. When the card drifts—usually a precision resistor opens—you see 3 % low servo position and the unit trips on “SERVO FAULT DIFF”; swap the board, re-torque the 20-pin plugs, and the numbers snap back to the original calibration. You’ll find this PCB in any Mark VI that still uses the original I/O scheme: paper-mill back-pressure sets, refineries, and every frame-7 that never upgraded to Mark VIe. Its value is repeatability: the divider network is laser-trimmed, so you get the same servo gain the turbine was commissioned with—critical for keeping old electromechanical overspeed bolts happy.
In a 2000-frame-7 combined-cycle block the Mark VI doesn’t read raw LVDTs—it wants clean, isolated ±10 V signals that represent servo position, speed bias, and exhaust temperature. The IS200TFBAH1ABA is the card that does the scaling. It sits in the VME rack, reads 4-20 mA from dual LVDTs, ±10 V from magnetic pickups, and thermocouple millivolts from the exhaust rake, then dumps the data onto the VME bus every 10 ms. When the card drifts—usually a precision resistor opens—you see 3 % low servo position and the unit trips on “SERVO FAULT DIFF”; swap the board, re-torque the 20-pin plugs, and the numbers snap back to the original calibration. You’ll find this PCB in any Mark VI that still uses the original I/O scheme: paper-mill back-pressure sets, refineries, and every frame-7 that never upgraded to Mark VIe. Its value is repeatability: the divider network is laser-trimmed, so you get the same servo gain the turbine was commissioned with—critical for keeping old electromechanical overspeed bolts happy.
Installation & Maintenance Pitfalls (Expert Tips)
LVDT common-mode blow-up—differential only, never ground
The LVDT inputs are true differential; land the shield on the wrong pin and you stuff 120 VAC into a 10 V amplifier—op-amp blows, card smells like popcorn. Always tie shield drain at the junction box only, float it at the card.
The LVDT inputs are true differential; land the shield on the wrong pin and you stuff 120 VAC into a 10 V amplifier—op-amp blows, card smells like popcorn. Always tie shield drain at the junction box only, float it at the card.
20-pin plug reversed—+24 V on –10 V pin cooks the amp
The two field headers are keyed alike but pin-outs mirror. Land the servo cable on the thermocouple header and you stuff +24 V into a 100 mV input—trace burns open. Match the white wire-stripe to the silk-screen arrow before you push the plug home.
The two field headers are keyed alike but pin-outs mirror. Land the servo cable on the thermocouple header and you stuff +24 V into a 100 mV input—trace burns open. Match the white wire-stripe to the silk-screen arrow before you push the plug home.
Conformal coat cracked—salt fog kills the reference
The board is coated, but the trim-pot area is masked. If the coat cracks, salt bridges the 2.5 V reference and you see 5 % offset on every channel. Scrape the salt, hit the area with 2100-FTG, and re-coat—problem gone for another decade.
The board is coated, but the trim-pot area is masked. If the coat cracks, salt bridges the 2.5 V reference and you see 5 % offset on every channel. Scrape the salt, hit the area with 2100-FTG, and re-coat—problem gone for another decade.
Battery dead—SRAM loses scaling table, servo hunts
The 3 V lithium cell backs the SRAM. When it drops below 2.2 V the scaling curve corrupts and the servo hunts ±2 %. Cell is solder-tab; cut it out, add a CR2032 holder on the faceplate, and reload the table via Toolbox-St—five-minute fix, no crane needed.
The 3 V lithium cell backs the SRAM. When it drops below 2.2 V the scaling curve corrupts and the servo hunts ±2 %. Cell is solder-tab; cut it out, add a CR2032 holder on the faceplate, and reload the table via Toolbox-St—five-minute fix, no crane needed.
IS200AEADH1ABA
Technical Deep Dive & Overview
IS200TFBAH1ABA is a 12-channel analog front-end frozen in 1999 silicon. A quad 741 op-amp array scales LVDT and speed signals; a 12-bit ADC converts them; an FPGA latches the data onto the VME bus every 10 ms. Because everything is hardware-scaled, you can swap the card hot and the controller never knows—just kill the 24 VDC field power first or you’ll arc-weld the 20-pin plugs. Think of it as a ruggedized signal conditioner that lives in a coal-dust cabinet; treat the differential inputs like instrumentation jewels and the servo loop will stay rock-solid for another thirty years
IS200TFBAH1ABA is a 12-channel analog front-end frozen in 1999 silicon. A quad 741 op-amp array scales LVDT and speed signals; a 12-bit ADC converts them; an FPGA latches the data onto the VME bus every 10 ms. Because everything is hardware-scaled, you can swap the card hot and the controller never knows—just kill the 24 VDC field power first or you’ll arc-weld the 20-pin plugs. Think of it as a ruggedized signal conditioner that lives in a coal-dust cabinet; treat the differential inputs like instrumentation jewels and the servo loop will stay rock-solid for another thirty years
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