The DS3800HMAC1G1E is the media access board that connects a GE Speedtronic Mark IV panel to its system communication bus and arbitrates that panel's access to the shared data highway. This listing is the circuit board itself in used condition, cleaned and tested, with a one-year warranty — a core communications spare for multi-unit Mark IV plants.

DS3800HMAC1G1E: the media access board itself

In a Mark IV, the HMAC board is the electronics behind the media access unit. GE classes it as a system bus module, and in normal service it sits beneath the DS3820MAUD interface panel, which adds the cable ports and the Cable A OK, Cable B OK and Watch Dog Timer OK status windows. The board carries the working parts: six red LEDs that line up with those panel windows, ten jumper switches that configure its behavior on the bus, a six-pin header, test points, transistors, and crystal-oscillator-timed logic. Its role is not to compute turbine control but to manage when and how its panel talks on the network that links the <R>, <S>, <T> and <C> cores and the operator interface.

Separating a bad board from a bad link

A panel-not-communicating fault does not automatically mean the HMAC has failed. The board is one link in a chain that includes the cabling, the far-end nodes, the power feed, and the jumper configuration. Work through the alternatives first:

• Read the status LEDs through the panel windows: a single failed cable path usually indicates a cable or remote-node problem, since the bus is dual-routed as Cable A and Cable B.
• Check the power feed to the board before reading anything into a watchdog indication.
• Reseat the board on its mating connector and confirm the panel connections are secure.
• Compare the ten jumper switches against the board being replaced — a configuration mismatch is a frequent cause of a new board that will not communicate.
• Confirm the other panels on the bus are healthy; one failing node can disturb the conversation for others.

When the wiring, power and configuration are verified and the fault stays with this board, replacement is justified.

Matching the 1G1E group code

The number reads as DS3800 for the Mark IV board series, HMAC for the media-access function, and 1G1E for the group/revision. The trailing revision is the field that varies between otherwise identical boards, so match it to the card you are replacing wherever possible. If your unit is a 1G1F or another revision, ask us and we will confirm whether this 1G1E is a suitable fit. See the GE Speedtronic Part Number Decoder for the full numbering logic.

The DS3820MAUD panel and other companion parts

Because the HMAC board normally works inside the DS3820MAUD module, it is worth confirming whether you need just the board or the complete module with its interface panel — they are ordered as different part numbers. On the signal side, the DS3800HDRA line driver/receiver board drives and receives the traffic that the HMAC's media access logic governs. Browse related items in the GE Mark IV DS3800 Boards collection or the wider GE Speedtronic Turbine Control Boards catalog.

Send these details with your request

To let us match and quote quickly, include:

• The full part number with suffix (DS3800HMAC1G1E), and whether you need the board only or the full DS3820MAUD module.
• A photo of the board label with its revision and GE codes.
• The turbine and Mark IV panel the board serves.
• Quantity and urgency, including any unit currently offline.

Request a Quote and we respond within 24 hours. We ship worldwide DDP, welcome purchase orders from qualified accounts, and can quote the bare board, the DS3820MAUD module, or the companion HDRA together.

General Information about the Product
Part Number	DS3800HMAC1G1E Mark IV DS3800
Description	GE General Electric DS3800HMAC1G1E DS3800HMAC Media Access Unit Mark IV
Condition	used Cleaned and Tested. With 1 Year Warranty.