DS3800HCMA1B1B: Dual Communication Control Card for Mark IV

The DS3800HCMA1B1B is a GE Speedtronic Dual Communication Control Card from the Mark IV (DS3800) generation, offered here used, cleaned and tested, with a one-year warranty. Its role is communication: the HCMA manages the exchange of data between boards and components inside the Mark IV drive, one of the functions that lets a triple modular redundant control panel behave as a single coordinated system.

What the HCMA Does on the Mark IV Data Path

Mark IV was GE's first Speedtronic platform to run triple modular redundant (TMR) control, with three control processors — <R>, <S> and <T> — voting two-out-of-three and a <C> communications processor tying the system to its operator interface. Mark IV communications were carried over RS-232 or RS-485 links between the control and connected devices. The HCMA lives in this communication layer; cards in the series typically carry configuration jumpers, status LEDs and two 34-pin connectors, with the jumpers defining how the board handles the signals it receives from, and transmits to, its neighbors. Those jumpers are set before installation because the card is sandwiched between other boards once fitted.

Prove the Communication Fault Before Swapping the Card

A communication or data-highway alarm does not always mean the HCMA has failed. The fault that most often imitates a bad communication card lives in the cabling or the board at the other end of the link. Before you replace this card:

• Check the LEDs. The onboard status indicators are your first clue; note their state before you disturb anything.
• Inspect the connectors. Reseat the two 34-pin connections and examine the cables for damage; a marginal link produces classic intermittent communication faults.
• Confirm the far end. A defect on the board the HCMA talks to can raise an alarm that appears to come from the HCMA itself.
• Verify power. Out-of-tolerance DS3800 supply rails can disrupt communication without the card being faulty.
• Match the jumpers. A replacement jumpered differently from the card you removed will not communicate correctly — record the original settings and replicate them exactly.

Reading DS3800HCMA1B1B

The number is built as DS3800 (Mark IV hardware family) + HCMA (dual communication control function) + 1B1B (group and revision). The trailing characters identify the exact build; GE advanced them as the card was re-run, so a 1B1B should be matched to a 1B1B unless your documentation confirms another group is compatible. Our GE Speedtronic Part Number Decoder details how the convention works. We keep to what the hardware and GE documentation confirm and avoid inventing channel counts or interface specifications.

Companion Communication and Processor Boards

The HCMA works among other DS3800 cards, including communication boards such as the DS3800HCMB and microprocessor boards like the DS3800HMPF. Browse the group in our GE Mark IV DS3800 Boards collection or the broader GE Speedtronic Turbine Control Boards range. If you are studying how communications evolved in later systems, Mark V vs Mark VI: DS200 to IS200 traces the shift to newer Speedtronic hardware.

Details That Help Us Quote Correctly

• The full part number with suffix (DS3800HCMA1B1B);
• The board revision and label markings — a photo is ideal;
• Your turbine model and confirmation of a Mark IV panel;
• Quantity and urgency, and whether you can share the original jumper configuration.

Request a Quote for This HCMA

This DS3800HCMA1B1B is cleaned, tested and warranted for one year. Press Request a Quote and we will respond within 24 hours with availability and lead time. We ship worldwide DDP and accept purchase orders from qualified companies; a label photo helps us confirm the exact group and revision you require.