IS220PSVOH1B servo output pack at a glance

Think of the IS220PSVOH1B as the muscle between the Mark VIe controller and the turbine's hydraulic servo valves. This servo output pack (PSVO) takes a position command over IONet and drives the valve to match, closing up to two independent position loops through its onboard WSVO servo driver. Mechanically it mounts on the TSVO servo terminal board; electrically it bridges one or two Ethernet networks to that board. A local processor with flash, RAM, a power supply, and an internal temperature sensor works alongside the servo acquisition board, and the whole pack is configured and monitored from ToolboxST.

Faceplate LEDs give you power (PWR), attention (ATTN), the ENet link and status indications, and the ENA enables at a glance. The infrared port on the front is not used on this pack, so do not read anything into it during troubleshooting.

Is it the pack, the valve, or the feedback? A pre-purchase checklist

Servo output problems are notorious for pointing the finger at the pack when the real fault is in the hydraulics or the wiring. Run this checklist before you buy an IS220PSVOH1B:

• Valve and coil: confirm the servo valve moves freely and its coil reads a sane resistance — sticking spools and open coils are common and cheap to find.
• Position feedback (LVDT/LVDR): a bad feedback element or its wiring makes the loop drift or oscillate; the pack is only as good as the feedback it receives.
• TSVO board and terminations: inspect the terminal board, its connector to the pack, and the field landings for damage or corrosion.
• Network and supply: verify the IONet link and the pack power at the faceplate LEDs before assuming the electronics failed.

If ToolboxST shows the pack online and healthy while the actuator still misbehaves, the evidence points away from the PSVO. Only when drive and feedback both check out at the board, and the pack still faults, is a replacement the right call.

How the H1B works with the TSVO terminal board

The PSVO and TSVO are a matched pair: the terminal board carries the field terminations for the servo coils and feedback, and the IS220PSVOH1B plugs onto it and does the processing. Remember two operational quirks. First, the pack can auto-reconfigure when you replace it, a behavior you enable or disable in the ToolboxST Component Editor. Second, when you replace the TSVO terminal board, the I/O pack does not auto-reconfigure — you must reconfigure it manually. Skipping that step is a frequent reason a good replacement pack looks dead on first power-up.

Decoding IS220PSVOH1B and the H1B ending

IS220 marks the Mark VIe distributed I/O pack family, PSVO is the servo output function, and H1B is the hardware revision and variant — the successor designation to the earlier H1A. Treat H1A and H1B as revisions to match, not as guaranteed drop-in equivalents, and check compatibility against your ControlST/ToolboxST version. For a field-by-field breakdown of a Speedtronic nameplate, use our GE Speedtronic Part Number Decoder.

Related servo and turbine control replacements

Sourcing a servo pack is often part of a broader spares refresh. The GE Mark VI IS200 Boards and GE Speedtronic Turbine Control Boards collections list the analog, discrete, and protection packs that share the same IONet backbone. Migrating from an earlier platform? The Mark V vs Mark VI: DS200 to IS200 guide covers how servo control moved from Mark V to Mark VI and Mark VIe.

Details that make your quote accurate

Please include:

• The complete part number and suffix (IS220PSVOH1B) and the revision on the label.
• A photograph of the pack nameplate.
• Turbine model and Mark VIe or Mark VI generation.
• Quantity and urgency, including any planned outage date.

This listing is a new-surplus unit supplied without the original box; see the table below for the exact condition and warranty as stated.

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