Description
Key Technical Specifications
- Manufacturer: GE Fanuc
- Product Type: Genius I/O Terminal Base Assembly
- Input Voltage: 115 VAC / 125 VDC
- Output Type: Current Source (4-20 mA)
- Channel Count: 6 Input Channels
- Output Accuracy: 0.15% @ 25°C
- Power Dissipation: 12 Watts
- Operating Temp: 0°C to 60°C
- Storage Temp: -40°C to 100°C
- Dimensions: 8.83″ H x 3.50″ W x 3.94″ D
- Features: Bus Switch, Output Hold, CPU Redundancy Support
Product Introduction
When your Genius I/O bus loses power, the entire rack goes dark. The GE IC660TBA026M is the terminal base that prevents this, serving as both the physical wiring interface and the power source for the attached I/O block. It’s not just a passive connector; it actively conditions the bus, provides termination, and ensures the 4-20mA current loops have a stable reference.
This module handles the dirty work of converting 115VAC or 125VDC into the regulated bus power your I/O cards need. With 0.15% accuracy and support for bus switching, the IC660TBA026M is critical for redundant systems where a single point of failure isn’t an option. Bottom line — it’s a legacy workhorse. Just remember that the “M” suffix often indicates a specific revision or manufacturing lot; while usually interchangeable, always verify the exact suffix if you’re replacing a failed unit in a high-availability system.
QA/QC Transparency SOP
- Intake & Origin Verification: We trace the lot and visually inspect the PCB for heat stress, especially around the power regulation components and the bus connector pins. We verify the IC660TBA026M suffix matches the label to ensure revision compatibility.
- Live Functional Testing: The module is seated in a verified Genius I/O test rack. We apply 115VAC/125VDC and verify the bus power rail stabilizes within spec before allowing the attached I/O block to initialize.
- Electrical Parameter Tests: Using a Fluke 87V, we measure the 4-20mA output accuracy across all 6 channels. We verify the 0.15% tolerance and check for ripple on the DC bus that could indicate failing filter capacitors.
- Firmware/Config Verification: We connect a Hand-Held Monitor (HHM) to the front port to read the module’s diagnostic registers. We verify it reports healthy bus status and correct termination resistance.
- Final QC & Anti-Static Packaging: The module is cleaned, terminal screws are torqued to spec (2.5-3.0 N·m), and it is sealed in ESD-safe shielding with a test report listing actual bus voltage and output accuracy.
Field Engineer Gotchas
- Bus Termination Errors: The IC660TBA026M often includes the bus termination resistor. If you remove this module without installing a terminator on the next block, the entire Genius bus will reflect signals and fail. Always verify termination before pulling a power block.
- AC/DC Input Confusion: This module accepts both 115VAC and 125VDC. Field techs sometimes assume it’s AC-only because of the “115V” label. Wiring 125VDC to an AC-only variant (or vice versa) can destroy the input bridge. Check the schematic and the specific suffix.
- Heat Dissipation: At 12 Watts, the IC660TBA026M runs warm. If it’s packed tightly in a sealed enclosure without airflow, the internal capacitors will dry out prematurely. Ensure at least 1 inch of clearance or active ventilation.
- HHM Port Damage: The front monitoring port is fragile. I’ve seen techs force the HHM connector in upside down, bending the pins. Always align the keyway. If the port is damaged, you lose diagnostic visibility, not just convenience.
GE IC660TBA026M
Application Scenarios
- Automotive Assembly Lines: Legacy GE Fanuc PLC-5 systems controlling paint shop conveyors. The IC660TBA026M powers the distributed I/O racks that monitor motor currents and safety gates, where a single bus failure stops the entire line.
- Water Treatment Plants: Remote pump stations running Series 90-30 controllers. The handles the 125VDC station power, converting it to bus power for level and flow transmitters, often in unconditioned outdoor cabinets.
- Pulp & Paper Mills: Wet, corrosive environments where I/O blocks are sealed in NEMA 4X enclosures. The provides the isolated bus power needed to prevent ground loops from corrupting 4-20mA signals from moisture sensors.
Real-World Case Study: A power plant’s GE Fanuc ESD system began tripping intermittently. Diagnostics pointed to “Bus Communication Errors.” The root cause was a failing that was dropping bus voltage during high-current inrush events. The module wasn’t dead, just degraded. Replacing it with a tested unit and verifying the 125VDC input stability resolved the ghost trips. Lesson: Don’t trust “passing” diagnostics if the hardware is 20+ years old.
FAQ
Can I use this for 24VDC systems?
No. The is specifically rated for 115VAC or 125VDC input. Using 24VDC will not power the bus. You need a different terminal base (e.g., IC660TBA024) for low-voltage applications.
Is the “M” suffix critical?
Usually, no. The is generally functionally identical to the base IC660TBA026. However, in redundant systems, mixing revisions can sometimes cause synchronization quirks. Best practice: match the suffix if possible, but verify with the HHM if substituting.
How do I test this without a full rack?
You can bench-test the power rails with a load, but you won’t see bus diagnostics. The requires the Genius bus protocol to report faults. For true verification, seat it in a known-good rack with an HHM.
What causes the 12W heat?
Linear regulation. The drops 115VAC/125VDC down to bus levels using older topology. That 12W is waste heat. If your cabinet is hot, this module will be hotter. Consider adding a small fan if ambient exceeds 50°C.
Can I hot-swap this module?
No. The powers the bus. Removing it will de-energize all attached I/O blocks and cause a system fault. Schedule replacements during a shutdown or with proper bypass procedures.
Why is my HHM not connecting?
Check the port pins. The monitoring port is prone to oxidation. Clean the contacts with electronic cleaner. If still dead, the internal UART may have failed, which means the module is end-of-life regardless of power status.
Is this compatible with IC670 chassis?
No. The is a Genius I/O component. IC670 (PACSystems) uses a completely different backplane and terminal base architecture. Do not force it.
