Allen BradleyControlLogix 1756 Chassis Power Supply, 85-265 V AC In, 5.1 V DC 13 A and 24 V DC 2.8 A Out, 75 W

Product Description

What this part is

The chassis power supply for an Allen-Bradley 1756 ControlLogix rack. It attaches to the left-hand end of any 1756 chassis and feeds the backplane: every controller, communication module and I/O module in that rack draws its logic power from this unit. Note that it does not occupy a numbered I/O slot — a 1756-A7 chassis still gives you seven usable slots with this supply fitted. It is not a controller, not a field-device 24 V supply and not a standalone bench supply; it powers only the backplane it is bolted to.

Decoding the catalogue number

1756 — the ControlLogix platform.P — power supply.A — AC input. This is the distinction that decides fit: 1756-PB75 is the 24 V DC input version of the same 75 W supply, and the two are not interchangeable on the supply side.75 — 75 W total backplane output. The larger 1756-PA72 and 1756-PA75R members of the family differ in output and in redundancy support./A — hardware series A. Series letter matters for firmware and revision matching on intelligent modules; on a passive power supply it is essentially a manufacturing revision.96348671-B01 — the Rockwell internal assembly/board number carried on this unit’s label, useful when cross-checking a repair quote or a stores record.

Published specifications

Input: 85–265 V AC, 47–63 Hz — wide range, so it works on 120 V and 240 V nominal supplies with no strapping or selector switchBackplane output: 5.1 V DC at 13 A and 24 V DC at 2.8 ATotal output power: 75 WMounting: bolts to the left end of a 1756 chassis; does not consume an I/O slotIndication: front-face power LEDRedundancy: this is the standard, non-redundant supply. Redundant chassis power requires the 1756-PA75R and its associated 1756-PSCA chassis adapter, neither of which is this part.Approvals: UL, CSA, CE, C-Tick class listings for industrial control equipmentWiring: line, neutral and protective earth on the captive terminal block behind the hinged cover

What these specs mean in practice

Rack design on ControlLogix is a power budget, and the 75 W total is the ceiling. Every module publishes a 5.1 V and a 24 V backplane draw; add them for the whole rack and confirm both individual rails and the combined wattage stay inside 13 A, 2.8 A and 75 W. It is entirely possible to stay within 75 W and still exceed the 24 V rail, because analogue and some communication modules lean heavily on 24 V. A rack that faults intermittently, or that a controller cannot see all of, is very often a power-budget problem rather than a bad module.

The wide 85–265 V input is one of the genuinely convenient things about this supply: no voltage selector to get wrong, and it rides through supply sag better than a narrow-range unit. It does not accept DC — if your cabinet is 24 V DC fed, you need the 1756-PB75.

Quantity and configuration

Sold as one power supply. Two are in stock at time of writing, so a matched pair for two racks is possible — ask before ordering if you need both.

What is not included

1756 chassis or backplane, ControlLogix controller, I/O or communication modules, slot filler modules, chassis-mounting hardware, AC supply cord or conduit fitting, 1756-PSCA redundant power adapter, controller battery or energy-storage module, and manual. This is the supply on its own.

Installation and setup notes

Remove chassis power before fitting or removing the supply; it is not a hot-swap item and pulling it live drops the entire rack, controller included. It bolts to the chassis and mates through a keyed connector — do not force it, and confirm the chassis is a 1756 series before assuming fit. Land a proper protective earth: ControlLogix backplane noise immunity and the module diagnostics both depend on it. After power-up, verify the front LED is on and that the controller sees every slot before returning the machine to service.

Interchange guidance

Interchangeable with any other 1756-PA75, in any series letter, on any 1756 chassis. Related but different parts, not substitutes: 1756-PB75 (24 V DC input), 1756-PA72 (different output rating), 1756-PA75R (redundant, requires 1756-PSCA), 1756-PH75 (125 V DC input). Substituting across those changes either the supply voltage or the rack’s power budget. There is no 1769 (CompactLogix) or 1746 (SLC 500) counterpart — those are different platforms with their own supplies, and the numbers are not transferable.