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CS8 Controller — Re-seating and Cleaning Internal Boards

Summary

The Staubli CS8 controller cabinet contains internal boards — most critically the STARC board and network interface cards — that work loose during transport due to vibration. A loose board is one of the most common causes of unexplained communication failures, "E" display on the CS8, EtherCAT errors, and random axis trips. The fix is usually straightforward: open the CS8, firmly press the boards back into their slots, optionally clean the contacts with isopropyl alcohol, and close. The procedure is documented in the MRMC Bolt Quick Start Guide — p.36. This is a standard operator maintenance task, not a specialist repair.

Symptoms

  • CS8 front display shows "E" instead of "A" at startup (communication error).
  • Flair reports EtherCAT errors or "Robot Says NO" after transport.
  • Random axis trips or velocity spikes on the track axis with no mechanical explanation.
  • Network connection to CS8 intermittent — works briefly then drops.
  • STARC board drive error LED lit on the board.

Community Guidance

[RESOLVED] Re-seat the STARC Board and Network Cards

Community — Gordon Eschke, Sebastian Opitz, Dan Gottesman — 2021–2025

The STARC board (which handles fiber optic communication between the CS8 and robot encoders) and the network interface cards are the most commonly loose components.

Gordon Eschke: "This is covered in the Bolt Guide under troubleshooting. Specifically re-seating the board in the CS8."

Dan Gottesman: "The biggest culprits seem to be the two boards in the CS8, followed by the fiber connections (both on the STARC board and inside the robot) — as far as things getting shaken loose go."

Gordon Eschke: "The only issue I'm aware of are the cards inside the CS8 sometimes requiring re-seating as covered in the guide. There should be a bracket/block that helps keep them in place, but even despite that, they may need re-seating every so often."

Procedure:

  1. Power off the CS8 completely (disconnect mains).
  2. Open the CS8 cabinet (remove the appropriate panel screws — typically the side or rear panel).
  3. Locate the STARC board (fiber optic communication board, PCI slot).
  4. Locate the two network interface cards in their slots.
  5. Firmly press each board all the way into its slot. A click or firm seating feeling confirms it is seated.
  6. Optionally clean the edge connector contacts with isopropyl alcohol and a clean cloth before re-seating.
  7. Close and power on. CS8 display should show "A" (not "E").

confidence_score: 0.92

[RESOLVED] Cleaning the Board Contacts — Fixes Intermittent Trip Issues

Community — Sebastian Opitz, Fabrizio (MRMC) — September 2022

Sebastian Opitz: "Fabrizio suggested cleaning the contacts of the slotted boards inside the CS8 with cleaning alcohol (ethanol, isopropyl). I was like 'yea right…', but that actually fixed it! Never occurred since."

Sebastian Opitz (on the track axis random trip): "My worst day ever so far was when my track axis kept tripping for no apparent reason on a set with 50+ people. Fabrizio told me I should simply clean the contacts on a PCB board inside the CS8. It did the trick, but cost me a few hours of total disgrace."

Cleaning options used by community: - Isopropyl alcohol (IPA) on a clean cloth applied to the board edge contacts. - An ordinary rubber eraser rubbed along the gold contacts.

Sebastian Opitz: "The Quick Start Guide only talks about 're-seating' the PCB — but I guess it's a good idea to clean the contacts when you're at it."

The MRMC Bolt Quick Start Guide (MRMC-1191-08, page 36) documents the re-seating procedure with photos. Request from support@mrmoco.com if you don't have this guide.

confidence_score: 0.92

[INFORMATIONAL] Transport is the Primary Cause

Community — Gordon Eschke, Sebastian Opitz — 2022

Boards work loose primarily during road transport (bumpy trucks, flights). Sebastian Opitz noted:

"The Bolt doesn't seem to like extended truck transport to locations and lots of dust — as is usual here in Dubai."

After any significant transport, especially long road hauls or air freight, visually inspect the CS8 boards before first power-on. A short prevention is to fit the bracket/mounting block supplied by MRMC that is designed to prevent the cards shifting.

confidence_score: 0.88

[INFORMATIONAL] CombiTac Connector (CS8 to Robot Arm)

Community — Simon Wakley — December 2022

The thick black cable from the CS8 to the robot base uses a CombiTac connector with spring-loaded fiber optic contacts. This can also cause issues, though Staubli rarely acknowledges it.

Simon Wakley: "The CombiTac connector between the CS8 and the robot has spring-loaded fiber optic connections and these can sometimes cause issues. You could try flexing the cable while the robot is running. Otherwise carefully take off and inspect, but do not touch the fiber optic bit. If the pendant says weird messages like 'over speed', could be that connector."

If you suspect the CombiTac: unplug it, inspect visually, reseat firmly. The fiber optic contacts are delicate — do not use tools on the fiber optic termination itself.

confidence_score: 0.85

[INFORMATIONAL] Fiber Optic Contacts Inside the Robot Arm

Community — Sebastian Opitz — December 2021

Sebastian Opitz: "It might be a bad connection on the optical outputs of the big plug at the back of the arm. I pulled them out with pliers to ensure proper connection."

This refers to the fiber optic connection at the base of the Bolt arm (under the rotating base housing). The fiber connectors here can work loose during heavy use. Use flat-nose pliers to push the connectors firmly home — do not apply force to the fiber itself.

confidence_score: 0.83

[INFORMATIONAL] CS8 Fuses and Breakers

Community — Stafford Wheaton — August 2025

If the CS8 will not power on at all (teach pendant dead, 24V lights off):

Stafford: "CS8? Check fuses on the back of the CS8, the 3-phase fuses in the power board, and the small black fuse on the PSU."

Locations: - Main fuses: Behind the small panel adjacent to the main power switch (3 fuses + 2 circuit breakers). - PSU fuse: Small black fuse on the power supply unit inside the CS8. - Remove mains power before accessing any fuse location.

confidence_score: 0.85

[INFORMATIONAL] Servo Amplifier Faults — Not DIY

Community — Simon Wakley — July 2025

If re-seating boards does not resolve the issue and the Staubli teach pendant shows a specific drive error on a particular axis:

Simon Wakley: "There are 3 double amplifiers in the back of the CS8. Each has a high and low current amp. High current = Rotate axis, Low current = Pan axis; next pair = Lift and Tilt; then Angle and Roll. If one of these amps faults you can replace it, but it's not terribly easy and sometimes you need to update the firmware to match your CS8."

Servo amplifier replacement is a specialist repair. Contact MRMC (support@mrmoco.com) or a Staubli-certified technician.

confidence_score: 0.85

Troubleshooting Order

When encountering CS8 communication errors or random axis trips after transport:

  1. Check the teach pendant — plug in and record any error codes.
  2. Re-seat the STARC board and network cards (see above).
  3. Check the CombiTac connector (CS8 to arm base).
  4. Check fiber optic connections inside the arm base.
  5. Check network cables from CS8 to the InTime network.
  6. Check fuses if controller will not power on at all.
  7. Servo amplifier diagnostics — contact MRMC if axis-specific drive error confirmed on pendant.

Official Documentation