DS3800HSQD - Low HP Sequence Board

DS3800HSQD - Low HP Sequence Board DS3800HSQD - Low HP Sequence Board

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Part No: DS3800HSQD
Manufacturer: General Electric
Function: Low HP Sequence Board
Series: Mark IV
Operating temperature: -33 to 56oC
Size: 8.25 cm high x 4.25 cm
Repair: 3-7 Day
Availability: In Stock
Country of Manufacturer: United States (USA)

Functional Description

DS3800HSQD is a Low HP Sequence Board developed by GE. It is a part of Mark IV control system. It is designed for easy installation and comes with connectors and components for optimal functionality. The board includes mounting holes in each corner for securing it with screws to the drive. The board is equipped with two 40-pin connectors and one 20-pin connector, each with retention levers, to secure ribbon cables in place. On the board's surface, you'll find a 50-pin connector and another 20-pin connector. The board features 1 erasable programmable read-only memory (EPROM) module. It also includes 1 amber indicator LED and 8 red indicator LEDs for status monitoring.

Installing the Ribbon Cable

Installing a ribbon cable, especially when connecting a 50-wire ribbon cable to the 50-pin connector, demands attention to detail and careful handling to ensure optimal functionality. Follow these detailed steps for a smooth and secure installation:

  • Consider Cable Routing: Prioritize proper cable routing to aid in the dissipation of heat from the board components. This is crucial for maintaining optimal temperature levels within the system.
  • Mindful Cable Placement: Fold the cable and guide it across the board, ensuring it runs along the inner side of the drive. It's essential to steer clear of any interference with airflow within the system to maintain efficient ventilation.
  • Handle with Care: Recognize the delicate nature of the 50 control signal wires within the cable and the plastic connector's sensitivity. To avoid any damage during installation or disconnection:
    • Firm Grip on Connector: Hold the connector firmly with one hand while handling it.
    • Gentle Removal: Exercise caution while removing the connector, ensuring a gentle approach without tugging or applying excessive force on the ribbon cable. This delicate handling prevents any accidental detachment of the delicate control signal wires from the plastic connector.

Upgrading to a Newer Board Version

  • If replacing the GE Low HP Sequence Board, the newer version may offer improvements in performance and component design.
  • Changes in the circuit layout may necessitate component repositioning.

Amber Indicator LED Status

  • A lit amber indicator LED indicates the board has received power and successfully completed startup diagnostics.
  • If the amber LED is not lit, it suggests a lack of power and unsuccessful startup diagnostics. In such cases, check the board's power source and attempt a restart for normal operations.


  • Speed and Position Sensors: Includes sensors that measure the rotational speed and position of the turbine shaft. These sensors may be based on different technologies, such as magnetic or optical encoders, and are designed to provide accurate and reliable speed and position measurements.
  • Signal Conditioning and Amplification Circuits: The signals from the sensors are typically weak and require amplification and conditioning before they can be processed by the control system. The SPI board includes circuits that perform this function, ensuring that the signals are of sufficient strength and quality to be used by the control system.
  • Redundant Sensors: To ensure high reliability, the board often includes redundant sensors. This means that there are multiple sensors measuring the speed and position of the turbine shaft, and the signals from these sensors are compared to ensure that they are consistent. If there is a discrepancy between the signals, the control system can use a voting algorithm to determine the correct value.
  • Fault-Tolerant Circuits: Designed with fault-tolerant circuits that can detect and respond to errors or malfunctions in the system. For example, if one of the sensors fails, the control system can automatically switch to a backup sensor, ensuring that the speed and position measurements remain accurate and reliable.
  • Diagnostic Features: Include diagnostic features that allow the control system to monitor the health of the board and detect any faults or malfunctions. This can include built-in self-tests or diagnostic algorithms that analyze the sensor signals and alert the control system if there are any issues.

Hardware Features

  • The hardware blueprint for the Mark IV panel was crafted with several key objectives in mind. One primary goal was to establish a foundational design capable of accommodating approximately 95% of customer panel needs without necessitating hardware alterations, except for the addition or removal of optional cards, modules, or cables.
  • The intent behind this approach was to empower software configurations to adapt and cater to diverse customer requirements. While rigorous testing against past demands validated the design, its effectiveness in meeting future customer needs will only be revealed over time.
  • Another pivotal objective was to ensure the repairability of the panel while a turbine is in operation. Considerable effort was dedicated to structuring the panel layout in such a way that most components could be easily and safely replaced, even while the panel remains energized and the turbine runs. To accomplish this, emphasis was placed on positioning modules housing the primary active components (which are likely to encounter failures) on the front doors, ensuring convenient accessibility for swift replacement.

WOC is happy to assist you with any of your GE requirements. Please contact us by phone or email for pricing and availability on any parts and repairs.


What is DS3800HSQD?
It is a Low HP Sequence Board developed by GE

How should I handle the 50-wire ribbon cable when connecting it to the 50-pin connector?
Ensure proper cable routing for heat dissipation from board components. Neatly fold the cable and route it across the board and along the interior side of the drive to avoid blocking airflow.

What precautions should I take when disconnecting the 50-wire ribbon cable?
Handle the cable delicately, as the 50 control signal wires are fragile. Avoid putting stress on the ribbon cable to prevent wire separation from the connector. Hold the connector firmly with one hand while gently removing it to avoid cable damage.

What does the amber indicator LED on the board signify?
The amber LED lights up when the board receives electrical power and successfully completes startup diagnostic tests. If it's not lit, it indicates a lack of power or unsuccessful startup diagnostics. In this case, check the power source and consider restarting the board.