Allen-Bradley 1756-PA75 ControlLogix 85-265V AC Standard Power Supply

Description

Key Technical Specifications

Product Introduction & Supply Chain Strategy

This product is a Brand New Surplus unit. It is not used, not pulled from a decommissioned plant, and not refurbished. All modules undergo rigorous quality verification to ensure OEM-level reliability. The Allen-Bradley 1756-PA75 is a standard 75-Watt AC power supply module mounted directly onto the left end of a ControlLogix chassis to convert AC utility power into stabilized DC voltages (1.2V, 3.3V, 5.1V, and 24V) required by local I/O cards and processors.

Stocking this module as New Surplus provides an indispensable insurance policy against total rack shutdown. Power supplies endure continuous thermal and electrical stress, making them prone to unexpected end-of-life failures. Sourcing New Surplus avoids the severe hazards of refurbished units—such as dried-out electrolytic capacitors, degraded switching transistors, and drifted voltage regulators—that cause erratic backplane faults. Securing verified New Surplus preserves full backplane voltage regulation, protects downstream processors and I/O cards, and significantly reduces Total Cost of Ownership by preventing multi-hour unscheduled downtime.

Installation & Configuration Guide

1.Pre-Installation (Prep & Safety):Safety warning: Ensure main AC feed is isolated before working on line terminals.

Isolate the main incoming AC power feed and apply Lock-Out/Tag-Out (LOTO) protocols on the distribution circuit breaker. Put on an anti-static wrist strap connected to cabinet earth ground. Inspect incoming line voltage across terminals L1 and L2/N using a calibrated multimeter to confirm zero potential.

2.Removal:

Unscrew the protective cover over the AC terminal strip. Disconnect the Line, Neutral, and Ground conductors from the screw terminals. Locate the top and bottom chassis release levers on the left side of the existing power supply. Fully depress the release levers and slide the power supply straight forward off the left mounting alignment pins of the 1756 chassis.

3.Installation (Clone & Seat):

Unpack the replacement 1756-PA75 within the static-safe area. Align the rear connector pins and side mounting guides with the leftmost position of the ControlLogix chassis. Slide the unit rearward firmly until the top and bottom chassis latches snap cleanly into place. Reconnect Ground, Neutral, and Line conductors to the screw terminals according to the terminal marking diagram.

4.Power-On & Testing:

Double-check all wiring connections and terminal screw torque settings. Reapply AC line power to the feed breaker. Observe the front panel green green POWER LED: a solid green illumination indicates that all internal DC voltage rails (1.2V, 3.3V, 5.1V, and 24V) are operating within spec and delivering clean power across the backplane.

1756-PA75

1756-PA75

1756-PA75

Firmware/Software Versions & Upgrade Notes

• Firmware Dependency: Hardware device only; the 1756-PA75 does not contain flashable firmware or backplane network communication logic.
• Chassis Compatibility: Fully compatible with all 1756 ControlLogix chassis series (1756-A4, 1756-A7, 1756-A10, 1756-A13, and 1756-A17) across Series A, B, and C.
• Loading Warning: Always perform a total backplane power calculation prior to installation. Ensure the combined current draw of all installed processors, communication bridges, and I/O modules does not exceed the maximum current limits on any individual voltage rail (specifically 13 A @ 5.1V DC or 75W total module output). Exceeding maximum capacity causes thermal shutdown or premature power supply degradation.

Frequently Asked Questions (FAQ)

Why is this New Surplus 1756-PA75 priced higher than refurbished power supplies?

Power supplies rely heavily on internal electrolytic capacitors and power semiconductors that degrade with age and heat. Refurbished power supplies often retain worn capacitors near their thermal limit, which causes voltage ripple, backplane noise, or sudden failure under full load. A power supply failure drops the entire chassis, taking down processors and field devices simultaneously. Paying a small premium for genuine New Surplus guarantees zero thermal hours, pristine capacitors, and full operational lifespan.

Are these 1756-PA75 units genuine Allen-Bradley original items?

Yes. We strictly guarantee that every 1756- power supply module is 100% Original OEM New Surplus. Sourced from audited plant reserves, system integrator project excess, and verified distributor surplus, each unit passes strict visual checks, mechanical latch inspections, and full-load voltage output testing before entering our inventory.

Can I hot-swap the 1756- while the ControlLogix chassis is operating?

No. The power supply provides the core DC operating power to the backplane for all installed modules. Removing the power supply under load immediately cuts backplane voltage, causing an abrupt shutdown of all controllers and I/O cards in that chassis. Always isolate the AC line and bring down the system safely before replacing the power supply.

What is the primary difference between the 1756- and 1756-PA72?

The 1756- delivers a higher total output power capacity (75W max compared to 52W max on the legacy 1756-PA72) and provides increased current output on the 5.1V DC backplane rail (13 A vs. 10 A). The 1756- serves as a direct drop-in functional upgrade for the older 1756-PA72 in applications requiring higher chassis component density.

What warranty coverage is provided with this power supply?

All New Surplus 1756- power supplies include our comprehensive 1-year replacement warranty. If the module experiences any functional performance issue within 12 months under standard operating parameters, we will immediately supply a replacement unit directly from our stock.