Description
- Model: GE IC660TBA026M
- Brand: GE Fanuc (Legacy Automation)
- Series: Genius I/O
- Core Function: Terminal assembly for Discrete Mixed I/O blocks (24/48 VDC).
- Product Type: Terminal Block Assembly (TBA)
- Key Specs: 16 Circuits | 24/48 VDC Sink/Source | Supports IC660BBA/BBD modules
GE IC660TBA026M
Key Technical Specifications
- Voltage Range: 18–56 VDC (covers 24 V and 48 V nominal)
- Circuit Count: 16 circuits (configurable as inputs or outputs)
- Current Rating: 2 A per circuit (8 A total per block)
- TBA Type: M-style (Discrete Mixed)
- Isolation: 1,500 V between I/O and Logic
- Compatibility: Pairs with IC660BBD020/021 electronics modules
- Wiring Terminals: Screw-type (accepts 12–22 AWG wire)
- Bus Protocol: Genius Bus (Serial)
- Status Indicators: LED diagnostics via the mated electronics module
- Protection: Internal electronic short-circuit protection (when used with correct module)
Application Scenarios & Pain Points
The Genius I/O system was a pioneer in distributed control, and while GE has moved toward modern RX3i systems, thousands of IC660TBA026M units are still the backbone of aging infrastructure. The “M” in the part number signifies a “Mixed” block, allowing for a high density of both inputs and outputs in a single footprint.
Typical Application Scenarios:
- Power Plant Turbine Control Handling discrete signals for auxiliary pumps and valve feedback where high reliability and galvanic isolation are mandatory.
- Municipal Water Treatment Linking remote lift stations to a central Series 90-70 PLC over long distances (up to 7,500 feet) via the Genius bus.
- Paper Mills & Steel Lines Used in harsh electrical environments where the robust “Block” design of the Genius series resists noise better than modern high-density rack I/O.
Case Study: The “Ghost” Fault in the Boiler Room
Background: A textile plant in the Midwest was running a Series 90-30 system with Genius I/O for its boiler control. Every few days, the system would trip on a “Loss of I/O” fault, but it would clear itself before the technician arrived.
The Problem: The IC660TBA026M terminal block had developed a hairline fracture in one of the internal bus connectors due to years of vibration and thermal cycling. When the boiler room got hot, the expansion caused a momentary open circuit.
The Solution: Because this is a legacy part, the client feared they would have to upgrade the entire cabinet to RX3i—a $50,000 project. We supplied a New Surplus IC660TBA026M from our inventory.
The Result: The maintenance team swapped the terminal assembly without having to change the electronics module or the PLC code. Total cost was under $1,000, and the “Ghost” fault hasn’t returned in six months.
Compatible Replacement Models
The Genius I/O line is modular; the terminal block (TBA) and the electronics module are separate pieces.
| Original Model | Component | Compatibility | Notes |
| IC660TBA026M | Terminal Block Only | ✅ Direct Match | Ensure the “M” suffix matches. |
| IC660BBA026 | Complete Block | ✅ Direct Match | Includes both TBA and electronics module. |
| IC660BBD020/021 | Electronics Only | ⚠️ Partial | This is the “brain” that plugs into the TBA026M. |
Engineer’s Tip: If you are upgrading to GE RX3i, you don’t necessarily have to rip out the IC660TBA026M. You can use a GBC (Genius Bus Controller) in the RX3i rack to continue talking to these legacy blocks, saving thousands in rewiring labor.
Troubleshooting Quick Reference
| Symptom | Likely Cause | Spare Related? | Quick Check | Action |
| Intermittent I/O Dropout | Loose TBA Screws | ✅ High | Torque all screw terminals to spec. | Tighten & check for corrosion |
| “Unit Flt” LED on Module | TBA/Module Connection | ⚠️ Medium | Inspect the pins between the TBA and Electronics. | Clean pins with contact cleaner |
| Burned Trace on TBA | Overcurrent / Short | ✅ High | Check for charring near the terminal screws. | Replace TBA immediately |
| I/O LED Red | Field Wiring Short | ❌ Low | Disconnect field wire; if LED clears, TBA is fine. | Trace field wiring for shorts |
❗ Technical Trap: The “M” vs. “S” Versions
I’ve seen people try to force an IC660TBA025 (Source only) electronics module onto an IC660TBA026M base. They look identical, but the internal busing is different. If you force them together, you risk a dead short that can take out your 24V power supply. Always check the label on the side of the baseplate before mating the electronics.
