The IC3600LRDH1A relay driver card at a glance

The IC3600LRDH1A is a relay driver card in the IC3600LRD group of GE's Speedtronic Mark I / Mark II turbine control, the oldest Speedtronic generation. Like the rest of the LRD group, its function is to translate low-level control commands into the switched drive that operates the panel's interposing and output relays — the relays that in turn actuate fuel and control valves, solenoids, ignition, contactors and annunciation on the turbine. The LRDH is one of several driver variants (C, D, H, J) that GE fielded across the Mark I and Mark II panels; the letter denotes the specific driver type, and it needs to match the slot the card came from.

Being a discrete, plug-in analog card, the LRDH drives each relay channel through its own transistor output stage. That is useful diagnostic news: faults tend to be per-channel rather than whole-board, so with a little probing you can usually tell whether you are dealing with one bad output or a board-wide problem.

Test the command and output stage before you buy

A relay that will not energize — or, just as often, one that will not release — can point to the driver, the relay, the field wiring or the upstream logic. Sort them out before ordering:

• Look for the drive command at the input. Verify the logic command for the suspect channel is present at the board. No command means the fault sits upstream, not on the LRDH.
• Probe the output stage. Check whether the channel's transistor output is actually switching. A driver that switches correctly into an open coil is not the problem; a driver that never switches is.
• Do not overlook a relay that will not drop out. Welded relay contacts or a failed suppression component can hold a circuit made even after the driver has released, which is easy to misread as a stuck output.
• Reseat and clean the edge connector. As with all IC3600 cards, contamination on the edge fingers or a poor rack seat produces intermittent operation that mimics a failing board.

Confirming the command in, the switching out and the relay itself keeps a scarce LRDH on the shelf until it is genuinely needed.

How to read the IC3600LRDH1A suffix

IC3600 is the Mark I / Mark II card series, LRD the relay-driver group, H the specific driver variant, and 1A the revision or dash detail. That last block is important on the LRDH in particular, because the group includes closely related revisions — an LRDH1A and an LRDH1B1D are the same basic card at different revision levels and are not automatically interchangeable. Match the entire number, suffix included. The GE Speedtronic Part Number Decoder explains the blocks in more depth.

LRDH revisions and companion boards

In the same panel the LRDH sits beside the other relay drivers of its group (LRDC, LRDD, LRDJ) and the interface and selector cards of the IC3600SIX group. When you are chasing an intermittent relay, being able to substitute a known-good driver of the exact revision is the fastest path to a diagnosis. Browse the group in our GE Mark I-II IC3600 Cards collection, or the broader control range in GE Speedtronic Turbine Control Boards. Later Speedtronic generations use different relay and output modules, so this card does not cross over to Mark IV, V or VI panels, and because Mark I-II predates triple-redundant control it is single-channel driver hardware rather than a voted R/S/T output.

Quote request checklist

Please send us:

• The complete part number and suffix as marked on the board, for example IC3600LRDH1A.
• A photo of the label and the board where possible.
• Turbine model and Speedtronic generation (Mark I or Mark II).
• Quantity and required lead time.

Request a quote on the IC3600LRDH1A

This IC3600LRDH1A is a used card, cleaned and tested. Click Request a Quote and we will reply within 24 hours. We ship worldwide DDP, accept purchase orders from qualified organizations, and can help you match the correct revision if you are unsure which LRDH your panel takes.

General Information about the Product
Part Number	IC3600LRDH1A Mark I-II IC3600
Description	IC3600LRDH1A By GE Speedtronic IC3600LRDH Relay Driver Card
Condition	used Clean and Tested With 1 Year Warranty.