Listed here as a used board, cleaned and tested and covered by a one-year warranty, the DS3800HMAC1G1F is the media access board that governs a GE Speedtronic Mark IV panel's access to the system communication bus. It is the circuit-board version of the media access unit, distinct from the complete DS3820MAUD module.

What the DS3800HMAC1G1F handles on the Mark IV bus

Every device on a shared bus needs rules for when it may transmit, and in the Mark IV the HMAC board provides them for its panel. GE describes it as a system bus module: it manages the panel's participation on the redundant communication bus so that data flows in an orderly way rather than colliding. The board is populated with six red status LEDs, ten jumper switches, a six-pin header, test points, transistors, and crystal-oscillator timing. When installed in a DS3820MAUD interface panel, those six LEDs report through windows marked Cable A OK, Cable B OK and Watch Dog Timer OK, giving a quick read on the two bus paths and the board's own health.

Jumpers, LEDs and the checks that come first

If a Mark IV panel loses communication, resist swapping the HMAC until the surrounding possibilities are cleared. The board's own indicators and configuration usually tell the story:

• Look at the Cable A OK and Cable B OK indications. One healthy path and one dark path points to a cable or far-end fault, not to this board — the redundant bus is behaving exactly as designed.
• Use the Watch Dog Timer indication as a health cue, but confirm the board's power feed before concluding the logic has stopped.
• Reseat the board firmly on its mating connector; an intermittent connection there imitates a board failure.
• Record and replicate the ten jumper-switch positions on any replacement — a jumper mismatch keeps a good board off the bus.
• Check neighboring nodes, because a single misbehaving panel can degrade communication for the whole bus.

Confirming these routinely saves a serviceable board and finds the true fault faster.

How to read DS3800HMAC1G1F

The number splits into DS3800 (the Mark IV board series), HMAC (the media-access function code), and 1G1F (the group/revision). Treat that trailing revision as the identifier to match against your installed board; a 1G1F and a 1G1E share the same function but are distinct builds. If you can only source a neighboring revision, contact us to confirm compatibility for your panel before ordering. Our GE Speedtronic Part Number Decoder details how the full string is composed.

Boards and modules related to the HMAC

The HMAC board is closely tied to two other parts. The DS3820MAUD is the complete media access module — the interface panel plus an HMAC board — so decide whether you need the board alone or the whole module. The DS3800HDRA line driver/receiver board sits alongside on the signal side, physically driving and receiving what the HMAC's access logic controls. Explore these and other Mark IV parts in the GE Mark IV DS3800 Boards collection, and if you are mapping an upgrade path our Mark V vs Mark VI: DS200 to IS200 guide is a helpful reference.

Request a quote with the right information

Give us these details and we will respond within 24 hours:

• The complete part number and suffix (DS3800HMAC1G1F), and whether you need the board or the full module.
• A photo of the board label showing revision and GE markings.
• The turbine and Mark IV panel the board supports.
• Quantity and urgency, noting any unit that is down.

Request a Quote to start. We ship worldwide DDP with duties and customs handled, accept purchase orders from qualified accounts, and can quote the HMAC board, the DS3820MAUD module, and the companion HDRA on a single quotation.

General Information about the Product
Part Number	DS3800HMAC1G1F Mark IV DS3800
Description	GE General Electric DS3800HMAC1G1F DS3800HMAC Media Access Board Mark IV
Condition	used Cleaned and Tested. With 1 Year Warranty.