The Field Interface for Two Electro-Hydraulic Servo Valves

On turbines controlled by GE's Speedtronic platform, valve positioning runs through dedicated servo terminal boards — and IS200TSVCH1A is the TSVC variant of that hardware. Its job, per GE documentation, is to terminate and condition everything a two-valve servo installation needs: bidirectional drive current for the servo coils of two electro-hydraulic valves, excitation and sensing for up to eight LVDT windings that measure valve position, and a pair of pulse-rate pickup inputs used on gas turbines for fuel flow. The wiring from the valve stand arrives on two barrier-type terminal blocks, 24 positions each, sized for up to #12 AWG conductors, with a shield strip bonded to chassis ground running beside them — shield landing discipline here matters as much as anywhere in the panel.

The board is not an island. It receives 28 V dc control power through connector J28, connects to the protection side of the system through external trip plugs JD1 and JD2, and carries relay K1, a trip override relay driven from the <P> protection function. It serves simplex, dual, and TMR system builds; in TMR service, jumper groups let each of the two servo outputs drive up to three coils so every control section keeps a grip on the valve.

Symptoms That Point Away from the TSVC Board

Most replacement TSVC boards are bought for problems that were never on the board. These patterns usually mean the fault is elsewhere:

• One LVDT reads wrong, its partner reads fine. LVDTs on the same regulator can be cross-checked against each other; documentation notes a bad sensor gets excluded from the feedback calculation. A single deviant sensor is a transducer or field-wiring problem in the overwhelming majority of cases.
• The valve slammed shut during an event. Trip commands arrive at this board by design through JD1/JD2 and the K1 relay. Pull the trip log before pulling hardware.
• Servo fault appeared right after maintenance. Check terminal block seating (the blocks are removable and screw-retained), cable connectors toward the servo electronics, and — on any recently changed board — the coil-current jumper positions.
• Valve hunts or oscillates. Instability usually lives in the hydraulics, the servo valve itself, or loop tuning; a passive termination board is an unlikely author of oscillation.
• Everything on the board died together. Shared causes first: the 28 V dc feed at J28, the cables to the I/O electronics, or the electronics pack. When a terminal board truly fails, there is very often visible cause — lightning damage, corrosion, burnt terminals — so look at the board before buying one.

What the EC Letters Mean on IS200TSVCH1AEC

GE part numbers in this family stack four fields: IS200 identifies the board series, TSVC the function (servo input/output termination), H1 the hardware group, and A the functional revision. The characters after that — EC on this unit's label — record manufacturing revision. Functionally you are ordering an IS200TSVCH1A; the EC tail tells us exactly which build you have, which is worth sending along if your site controls revisions tightly. The full field-by-field breakdown lives in our GE Speedtronic Part Number Decoder.

Compatibility Notes for Your I/O Layout

Published references are unambiguous on pairing: TSVC belongs with the PSVO servo I/O pack and the WSVO servo driver, and is not compatible with the VSVO processor card. If your servo loop runs through a VME rack with VSVO cards, the terminal board you need is more likely the TSVO type — check the acronym printed on the board before committing. For platform context, from legacy panels through the IS200 line, see Mark V vs Mark VI: DS200 to IS200; for the rest of the family, browse GE Mark VI IS200 Boards.

Build a Complete Quote Request

A quote goes out fastest when we can match your hardware on the first pass. Include:

• The label string exactly as printed — here, IS200TSVCH1AEC — plus a photo if possible
• Turbine model, fuel/steam application, and control architecture (simplex, dual, TMR)
• Mating servo electronics part number, if known
• Quantity, acceptable condition, and your deadline

IS200TSVCH1AEC: Ready to Quote

This board is offered used, cleaned and tested, with warranty terms shown in the table below. Send a Request a Quote and you will have our answer within 24 hours — worldwide delivery on DDP terms, purchase orders accepted.

General Information about the Product
Part Number	IS200TSVCH1A Mark VI IS200
Description	IS200TSVCH1A By General Electric IS200TSVCH1AEC Servo Terminal Board
Condition	used Cleaned and Tested. With 1 Year Warranty