IRB 6700 SMB Unit Replacement Guide

The ABB IRB 6700 is a robust industrial robot, but like any complex machinery, components can eventually require replacement. The Serial Measurement Board (SMB) unit is a critical electronic component responsible for processing resolver feedback and managing axis calibration data. When it fails, it can lead to communication errors, calibration issues, or complete axis malfunction.

Replacing the SMB unit (3HAC046645-001) requires precision and adherence to safety protocols, especially concerning electrostatic discharge (ESD). This guide goes beyond the basic manual steps, providing practical context and emphasizing crucial details to ensure a successful and safe replacement process for your IRB 6700.

Why Replace the SMB?

While the manual details the how, understanding the why is also important. SMB replacement is typically necessitated by:

Component Failure: Indicated by specific error codes related to resolver data or SMB communication shown on the FlexPendant.
Irrecoverable Calibration Data: Corruption of the stored calibration parameters.
Physical Damage: Though less common due to its protected location.

Before You Begin: Safety & Preparation are Paramount

1. Power Down Completely

This is non-negotiable. Before accessing any internal components, ensure all power is disconnected.

Turn off the main power supply to the robot controller. Follow the proper shutdown procedure for your specific controller cabinet (Single or Dual).
Turn off any auxiliary hydraulic or pneumatic pressure supplies connected to the robot system.
Lockout/Tagout: Apply appropriate lockout/tagout procedures to prevent accidental power restoration while you work.

2. ESD Protection: Critical for Survival

The SMB unit is highly sensitive to Electrostatic Discharge. Failure to take precautions will damage the new unit.

Wear a Grounded Wrist Strap: Connect it to the designated ESD connection point on the robot or controller before handling the SMB unit.
Use an ESD-Safe Mat: If possible, work on an ESD-protective surface.
Handle by Edges: Avoid touching connector pins or components on the board.
Keep New Unit Bagged: Leave the replacement SMB in its static-shielding bag until the moment of installation.

3. Gather Your Tools & Parts

Referencing section 4.4.3 Replacing the SMB, ensure you have:

Correct Replacement SMB Unit: Verify the spare part number (See Product manual, spare parts - IRB 6700).
Standard Toolkit: Including necessary screwdrivers/bits (See section 7.6 Standard toolkit).
ESD Bag: For storing the removed unit.

4. Locate the SMB Unit

The SMB unit resides within the SMB/BU (Brake Release Unit) recess on the robot frame. Familiarize yourself with its location as shown in the manual figure xx1300000740.

SMB Location Diagram (xx1300000740)

Figure: SMB unit location within the SMB/BU recess on the robot frame

SMB Replacement Workflow

flowchart TD A[Start: Prepare for SMB Replacement] --> B[Power Down Robot] B --> C[Apply ESD Protection] C --> D[Gather Tools & Parts] D --> E[Remove SMB Cover] E --> F[Disconnect Battery Cable] F --> G[Disconnect SMB Connectors] G --> H[Unscrew SMB Mounting Bracket] H --> I[Remove Old SMB Unit] I --> J[Store in ESD-Safe Bag] J --> K[Unpack New SMB Unit] K --> L[Install & Secure New Unit] L --> M[Reconnect All Cables] M --> N[Refit Cover & Battery] N --> O[Power Up Robot] O --> P[Update Revolution Counters] P --> Q[Verify Calibration] Q --> R[Perform Test Run] R --> S[Complete: Document Replacement] style A fill:#d1ecf1,stroke:#17a2b8 style B fill:#f8d7da,stroke:#dc3545 style C fill:#fff3cd,stroke:#ffc107 style J fill:#d4edda,stroke:#28a745 style P fill:#e2e3e5,stroke:#6c757d style Q fill:#e2e3e5,stroke:#6c757d style R fill:#e2e3e5,stroke:#6c757d style S fill:#d4edda,stroke:#28a745

Figure: Complete SMB replacement workflow with critical steps highlighted

Step-by-Step Removal Procedure

1

Access the SMB/BU Recess

a Carefully remove the small battery cover located on the main SMB cover (xx1300000829).
b Disconnect the SMB battery cable. Gently remove the battery pack.
c Unscrew and remove the main SMB cover (xx1300000669), taking care not to strain any attached cables if you chose not to disconnect the battery (not generally recommended for SMB replacement).

Critical: Remember that disconnecting the battery will require updating the robot's revolution counters later. See section 1.3.8 WARNING - Safety risks during handling of batteries for handling precautions.

2

Disconnect SMB Connectors

a Ensure your ESD wrist strap is properly grounded.
b Carefully disconnect all cables connected to the SMB board. These typically include R1.SMB1-3, R1.SMB4-6, and R2.SMB as shown in figure xx1300000728. Note their orientation for correct reconnection.

Taking a quick photo of the connector orientations before removal can be extremely helpful during reassembly.

3

Remove the SMB Unit

a Unscrew the attachment screws holding the SMB unit's mounting bracket (xx1300000730).
b Gently slide the SMB unit, still attached to its bracket, out of the recess.
c Immediately place the removed SMB unit into an ESD-protective bag.

Step-by-Step Refitting Procedure

1

Prepare the New SMB Unit

a Ensure your ESD wrist strap is properly grounded.
b Carefully remove the new SMB unit from its static-shielding bag, handling it by the edges or bracket.

Take this moment to visually inspect the new unit for any obvious physical damage or shipping issues before installation.

2

Position and Secure the New Unit

a Align the SMB unit (on its bracket) with the mounting points inside the recess.
b Gently slide it into position (xx1300000730).
c Secure the bracket with its attachment screws. Do not overtighten initially.

3

Reconnect Cables

a Reconnect all cables (R1.SMB1-3, R1.SMB4-6, R2.SMB) to their corresponding positions on the new SMB board, ensuring correct orientation (xx1300000729, xx1300000728). Ensure connections are secure.

Note: If you are also working on the Brake Release Unit (BRU), ensure its connectors (X8, X9, X10) are properly connected as well (xx1300000670).

4

Refit Covers and Battery

a Ensure the SMB/BU cover's sealing (O-ring 21522012-429) is clean and undamaged. Replace if necessary and apply sealant like Sikaflex 521FC (3HAC042559-001) if specified for your maintenance level.
b Carefully route the battery cable through the recess opening (xx1300000834).
c Secure the main SMB cover with its attachment screws (xx1300000669).
d Place the battery back into its compartment (xx1300000829).
e Reconnect the battery cable.
f Refit the small battery cover.

Critical Post-Replacement Steps: Don't Skip These!

1. Update Revolution Counters

This is absolutely essential. Replacing the SMB or disconnecting its battery resets the stored turn count for each axis. Failure to update will lead to incorrect positioning and potential collisions.

Power up the controller and robot.
Manually jog the robot axes precisely to their calibration marks (See section 5.3 Calibration scale and correct axis position - xx1200001073).
Using the FlexPendant, navigate to the Calibration menu and follow the procedure for "Update Revolution Counters" (See section 5.5 Updating revolution counters). Ensure you select the correct robot and axes.

2. Verify Calibration

Double-verification is essential to prevent costly misalignments that could lead to production issues or safety hazards.

After updating revolution counters, double-check the calibration position very carefully using the jogging window or a MoveAbsJ routine to zero position (See section 5.6 Checking the calibration position).
Confirm all axes align perfectly with their calibration marks (xx1200001073).

3. Perform a Safe Test Run

Gradual testing is critical to ensure safety and prevent potential damage from undetected calibration issues.

Before resuming automatic operation, perform thorough testing in manual mode at reduced speed.
Run the robot through its typical motion range, paying close attention to positioning accuracy and any unusual behavior.
Observe all safety protocols outlined in section 1.3.4 DANGER - First test run may cause injury or damage!

Impact on Absolute Accuracy (AbsAcc) Option

If your IRB 6700 is equipped with the Absolute Accuracy (AbsAcc) option (indicated by a sticker near the rating plate), replacing the SMB has further implications:

AbsAcc Data is Lost: While the standard calibration data (resolver offsets) is usually pre-loaded on a replacement SMB from ABB, the unique compensation parameters generated during the original AbsAcc calibration are specific to the individual robot and are stored on the original SMB. Replacing the SMB effectively removes this high-accuracy compensation data.
Standard Calibration Required: You must still perform the standard calibration procedures (updating revolution counters, potentially Pendulum calibration) after SMB replacement just to get the robot operational.
Full AbsAcc Re-calibration Needed: To restore the robot to its certified Absolute Accuracy performance, a full re-calibration using the CalibWare tool (or equivalent ABB procedure) is required. Simply updating revolution counters is insufficient for AbsAcc. Plan for this additional calibration step if maintaining high Cartesian accuracy is critical for your application.

Troubleshooting Common Post-Replacement Issues

Failure to Update Revolution Counters

Symptoms:

The FlexPendant shows errors during the update process
Calibration status remains 'Unsynchronized' or 'Not Updated'

Potential Causes:

Incorrect manual positioning of axes before attempting the update
Loose or incorrectly seated cable connections on the new SMB
Faulty connection between the SMB and the main computer

Solutions:

Re-verify Manual Position: Double-check that all axes are precisely aligned with their calibration marks.
Check Connections: Re-access the SMB recess (following ESD precautions) and firmly reseat all connectors.
Inspect Robot Cables: Check the main robot signal cable for damage or loose connections.

Inaccurate Positioning After Update

Symptoms:

Robot reports successful revolution counter updates but has physical inaccuracy
Positions are misaligned with calibration marks when commanded to zero

Potential Causes:

An axis was not exactly on its calibration mark during update
Incorrect calibration data loaded onto the replacement SMB
Underlying mechanical issue masked by the previous SMB fault

Solutions:

Re-Update Carefully: Repeat the process of manually jogging precisely to the calibration marks and updating the revolution counters. Pay extra attention to axes 4 and 6.
Perform Standard Calibration: If simple updating fails, a full standard calibration using the Calibration Pendulum method might be necessary.

Important Additional Considerations

Data and Configuration: What's Stored Where?

Understanding where crucial data resides helps clarify why certain steps (like updating revolution counters) are mandatory after an SMB replacement:

On the SMB:

Resolver Offsets (Standard Calibration Data): This fundamental data defines the precise relationship between physical zero position and electrical zero signal. A new SMB unit should come pre-loaded with nominal standard calibration data.
Revolution Counter Values: These track the motor rotations for each axis. This data is volatile and depends on the battery. When the battery is disconnected or the SMB is replaced, this count is lost.
Absolute Accuracy (AbsAcc) Compensation Data (if applicable): These unique parameters are NOT typically pre-loaded on a standard replacement SMB.

In the Controller (Main Computer):

Robot Programs (RAPID): Your motion and logic instructions.
System Configuration: Parameters defining TCPs, Wobjs, system settings, I/O configurations, etc.
Controller-Level Logs: Event logs, error history.

Estimated Time and Effort

30-60
min Physical Replacement: For an experienced technician familiar with the IRB 6700 and proper ESD procedures, the physical swap of the SMB unit (opening covers, disconnecting/reconnecting, closing covers).
30-60
min Revolution Counter Update & Verification: Manually jogging the robot precisely to its calibration marks and performing the FlexPendant update procedure, depending on the robot's accessibility and the technician's proficiency.
2-4
hrs Potential Standard Calibration (Pendulum): If a full standard calibration is deemed necessary, this adds significant time, including setup and execution.
4-8
hrs Absolute Accuracy Re-calibration (CalibWare): This is the most time-consuming step, depending on the specific CalibWare procedure used and the robot cell complexity.

Total Downtime:

Plan for a minimum of 1-2 hours for a basic SMB swap and revolution counter update. If full standard or AbsAcc calibration is required, the downtime will increase substantially. Always factor in safety checks and test runs.

Conclusion

Replacing the SMB unit on an IRB 6700 is a manageable task for trained technicians, but it demands meticulous attention to detail, especially regarding ESD protection and post-replacement calibration. By following these steps carefully and understanding the critical importance of updating revolution counters, you can confidently restore your robot's functionality and ensure its continued safe and accurate operation.

Always prioritize safety and consult the full ABB documentation if any step is unclear. For robots with the Absolute Accuracy option, remember that a complete CalibWare recalibration will be necessary to restore full accuracy performance.

Mastering IRB 6700 Repair

SMB Unit