Allen-Bradley 1756-L73 ControlLogix Processor 8 MB – Repair Service Available
Allen-Bradley 1756-L73 8 MB ControlLogix 5570 controller. NJT Automation offers mail-in repair for the 1756-L73 with a 1-year warranty; replacement pricing is available on request.
Mail-in repair available now. Returned with a 1-year warranty. Replacement pricing on request.
Actual NJT inventory photos
| Part Number | 1756-L73 |
| Price | On Request Previously sold for $849.99 - $3,999.99 USDAvailability and condition determine final quote. |
| Description | ControlLogix 5570 controller, 8 MB. |
| Shipping |
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| Warranty | 1-year full-function warranty provided by NJT Automation. Warranty details
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| Returns | 90-day free returns. View return policy |
| Exchange | Send us your defective 1756-L73 after your purchase for a 10% core credit. We also purchase old or damaged parts outright. |
| Availability | Sourced on request We do not have a 1756-L73 on the shelf right now. We can source one through our supplier network; request a quote and we confirm availability, price and lead time before you commit. | ||||||||
| Sourcing | Sourced through our Level 1 network of vetted US suppliers. Each unit is checked before it ships and carries the same NJT warranty and return policy as our own stock. Quotes within one hour during business hours; typical delivery 3–5 business days, next-day air available. Sourced parts are not available for local pickup. | ||||||||
| Repairs | 1756-L73 Mail-In Repair ServiceEstimated: $1,440.00 | ||||||||
Part Number Decoder | ControlLogix 5570 controller 1756L73
Decoded from the Rockwell Automation catalog-number structure. Series and firmware revision are printed on the product label, not encoded here. | ||||||||
Series & Revisions | No series in stock today; request a series above. All series use the 1756-ESMCAP energy-storage module and a 1784-SD1 / SD2 card; no battery. Series notes: Studio 5000 keys on catalog number and firmware revision, not series. | ||||||||
Intended Use | Intended for plant-wide discrete, process, and motion control applications. ControlLogix controllers run high I/O-count machines, batch and continuous process lines, and coordinated multi-axis motion from a single chassis, with redundancy and plant-network connectivity when the application calls for it. Typical homes are automotive and tire plants, food and beverage lines, water and wastewater, oil and gas skids, and large packaging systems. | ||||||||
Physical Data | Weight and DimensionsWeight0.87 lb (0.39 kg)H × W × D5.7 × 1.4 × 5.7 in. (145 × 35 × 145 mm)
Product weight and dimensions are typical manufacturer-published values and may differ by series or option. Shipping box and weight are estimates for freight planning; the packed unit may ship in a different box. | ||||||||
Similar Part Numbers | |||||||||
| Category | ControlLogix | ||||||||
| Part Number | 1756-L73 | ||||||||
| Manufacturer | Allen-Bradley | ||||||||
Previously sold 1756-L73
4 soldNJT Automation has supplied and shipped 4 1756-L73 ControlLogix 5570 controllers since 2024; request a quote and we will source another from our supplier network.
- Sold
- 4 since 2024
- Series
- B × 2, A × 1
Image gallery38 PHOTOSActual units photographed by NJT
Can the 1756-L73 be repaired?
Yes. NJT Automation repairs the 1756-L73 by mail-in: diagnostic evaluation, component-level repair and a functional test, backed by a 1-year full-function warranty.
Option 1
NJT managed repair
- Evaluation
- Free. No repair, no charge.
- Shipping
- Prepaid UPS label both ways.
- Pricing
- $650 minimum. Rush service available.
- Warranty
- 1-year full-function warranty included; 2- and 3-year options.
Option 2
Independent repair bids. Compare quotes from independent repair technicians. Post your repair on RepairMode to receive competitive bids from experienced technicians. Each technician sets their own pricing and warranty.
Common Failures
Failure patterns we regularly see on ControlLogix 5570 controller hardware like the 1756-L73:
- Scrolling status display blank or unreadable
- Backplane communication faults from bent chassis pins after repeated module swaps
- Program lost on power cycle: energy storage module (1756-ESMCAP / ESMNSE) failing to hold the controller through a save
- Solid red OK LED (nonrecoverable major fault) that returns after clearing
- SD card corruption preventing the stored project from loading at power-up
Fault code reference
1756-L73 Fault Codes
42 codes · 1756-RD001
Fault codes a ControlLogix 5570 controller reports on the Major Faults tab in Studio 5000 Logix Designer / RSLogix 5000 as Type:Code (T:C), as documented in Rockwell Automation publication 1756-RD001. Use them to narrow a problem down to the unit, its wiring or the application before sending it in for repair.
| Code | Fault | What it indicates |
|---|---|---|
| T01:C01 | Power-up fault | Power was lost and restored while the controller was in RUN mode. |
| T01:C16 | Power-up fault | I/O communications configuration fault detected at power-up. |
| T01:C40 | Power-up fault | Energy storage module or battery failed during the last power-down; retained data may be lost. |
| T01:C60 | Power-up fault | Non-recoverable fault. The controller must be reflashed or returned for repair. |
| T01:C61 | Power-up fault | Non-recoverable fault with saved diagnostic information. |
| T01:C62 | Power-up fault | Non-recoverable fault with saved diagnostic information and stored user program. |
| T03:C16 | I/O fault | An I/O module connection failed on a module marked as required. |
| T03:C20 | I/O fault | Unable to read ControlBus chassis information; the chassis may be bad. |
| T03:C21 | I/O fault | Unable to read ControlBus chassis information; the chassis may be bad. |
| T03:C23 | I/O fault | At least one required connection was not established before going into RUN mode. |
Show 32 more codes
| T04:C16 | Program fault | Unknown instruction encountered. |
| T04:C20 | Program fault | Array subscript too large, or CONTROL data type POS or LEN invalid. |
| T04:C21 | Program fault | CONTROL data type LEN or POS less than 0. |
| T04:C24 | Program fault | Unknown data type passed to a subroutine. |
| T04:C31 | Program fault | JSR or RET did not pass as many parameters as expected. |
| T04:C34 | Program fault | A timer instruction had a negative value for its PRE or ACC. |
| T04:C42 | Program fault | JMP to a label that did not exist or was deleted. |
| T04:C82 | Program fault | Could not re-enter an executing SFC routine. |
| T04:C83 | Program fault | Value out of range. |
| T04:C84 | Program fault | Stack overflow: stack too small to perform the operation. |
| T04:C85 | Program fault | Invalid routine type. |
| T04:C89 | Program fault | Target step does not exist in the specified routine. |
| T04:C90 | Program fault | A safety instruction occurs outside a safety task. |
| T04:C91 | Program fault | Equipment phase instruction cannot be called from a program. |
| T04:C94 | Program fault | Nesting limits exceeded. |
| T04:C990–C999 | Program fault | User-defined major fault raised by the application. |
| T06:C01 | Watchdog fault | Task watchdog expired: an infinite loop, an over-complex program or a higher-priority task starved the task. |
| T07:C40 | Nonvolatile fault | Store to nonvolatile memory (CompactFlash / SD) failed. |
| T07:C41 | Nonvolatile fault | Load from nonvolatile memory failed: controller type mismatch. |
| T07:C42 | Nonvolatile fault | Load from nonvolatile memory failed: controller revision mismatch. |
| T07:C43 | Nonvolatile fault | Load from nonvolatile memory failed: bad checksum. |
| T07:C44 | Nonvolatile fault | Failed to restore processor memory. |
| T07:C50 | Nonvolatile fault | Security certificate invalid. |
| T08:C01 | Mode change fault | Mode change inhibited because a download is in progress. |
| T11:C01 | Motion fault | Actual position of the axis exceeded the positive overtravel limit. |
| T11:C02 | Motion fault | Actual position of the axis exceeded the negative overtravel limit. |
| T11:C03 | Motion fault | Actual position exceeded the position error tolerance. |
| T11:C04 | Motion fault | Encoder channel A, B or Z connection failed. |
| T11:C05 | Motion fault | Encoder noise event detected, or encoder signals not in quadrature. |
| T11:C06 | Motion fault | Drive fault reported by the servo drive. |
| T11:C07 | Motion fault | Synchronous connection to the servo module failed. |
| T11:C08 | Motion fault | Hardware failure in the servo module. |
Where the manual's only remedy for a code is to replace the unit or module, the code is pointing at a hardware fault inside that part. Those are the faults NJT Automation repairs at component level, so a repair quote is usually the first thing to check before buying a replacement.
Source: Rockwell Automation publication 1756-RD001, Logix 5000 Controller and I/O Fault Codes. Codes are listed as documented; fault behaviour can vary by firmware revision, so confirm against the manual for your unit's series.
Photos by NJT Automation; test videos from NJT or network repair technicians.
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