When Your Universal Robots Teach Pendant Stops Working
If your Universal Robots (UR) teach
pendant is not working, you lose direct access to programming, diagnostics, and
robot control—often leading to immediate production downtime.
This issue can appear suddenly or develop
over time, depending on whether the root cause is electrical, mechanical, or
software-related.
What Does a UR Teach Pendant Not Working Mean?
A “not working” UR teach pendant
typically means partial or total loss of HMI functionality, including:
- Black or blank screen (no display)
- Touchscreen not responding
- Stuck on PolyScope boot screen
- Intermittent or lost connection
- Safety lock preventing operation
⚠️ This is different from:
-
“Dead pendant”→ completely no power
-
“Black screen only”→ display issue but system may still run
This page covers all combined failure
scenarios.
Quick Fix Checklist for UR Teach Pendant Issues
Before deep troubleshooting, try these:
- Power cycle the UR control box
- Reseat teach pendant cable at controller
- Inspect cable for bending damage or loose connector
- Release all E-stops and reset safety
- Verify control box power input
- Reconnect pendant after reboot
These steps resolve most temporary,
connection, or safety-related faults.
Root Causes of UR Teach Pendant Not Working
1. UR Teach Pendant Black Screen (Power Issue)
Symptoms
- Screen completely black
- No UR logo on startup
- Controller appears inactive
Root Causes
- Control box power supply failure
- Blown fuse or unstable AC input
- 12V logic power missing
Fix
- Verify AC input and power stability
- Check controller LEDs (12V / 24V / 48V)
- Inspect internal PSU
If 12V logic power is down, the
pendant will not boot at all.
2. Connection Lost (Cable / Connector Issue)
Symptoms
- Pendant disconnect warnings
- Screen flickers when moving cable
- Intermittent control
Root Causes
- Cable fatigue (common in high-cycle use)
- Damaged connector pins
- Loose connection
Fix
- Reseat connector firmly
- Inspect for cuts, kinks, or wear
- Replace cable or pendant
UR Hardware Insight
-
CB3→ yellow connector, older architecture
-
e-Series→ black connector, updated communication system
e-Series may involve USB-based
recovery or firmware differences.
3. Touchscreen Not Responding (HMI Failure)
Symptoms
- Display works, but no touch input
- Delayed or inaccurate response
- Cannot interact with UI
Root Causes
- Touch panel degradation
- Oil / dust contamination
- Internal ribbon cable issue
Fix
- Clean screen properly (industrial wipes)
- Restart system
- Replace touchscreen module if needed
4. Stuck on Boot Screen (PolyScope Not Loading)
Symptoms
- Frozen on UR startup logo
- Boot loop or crash
- Cannot enter main interface
Root Causes
- Corrupted PolyScope system
- Failed update
- SD card / storage failure
Fix
- Restart controller
- Reinstall or update PolyScope
- Reflash or replace SD card
⚠️ Critical Warning
Always back up before
reinstall:
- .urprograms
- installation files
- robot configurations
Data loss here is permanent.
5. Safety Lock (E-Stop / Deadman Switch Issue)
Symptoms
- Pendant powers on but cannot control robot
- Safety or protective stop active
- System locked even after reset
Root Causes
- Emergency stop engaged
- Safety relay interruption
- External safety circuit fault
Often Overlooked Cause
- Faulty Deadman Switch (3-position enable switch)
Fix
- Release all E-stops
- Reset safety system
- Check safety I/O and relays
- Test Deadman switch responsiveness
A faulty Deadman switch can block
operation even when everything else is normal.
6. Internal Hardware Failure (Screen / PCB / Aging)
Symptoms
- Random shutdowns
- Screen flickering or glitches
- Fully unresponsive pendant
Root Causes
- PCB damage
- Aging components
- Heat / vibration / humidity exposure
Fix
- Test with a known-good pendant
- Replace unit (OEM or refurbished)
- Repair internal components (advanced)
Pro Diagnostic Method (Avoid Wrong Replacement)
To isolate the real issue:
- Test with a spare pendant
- Check controller LED status
- Review UR logs (if accessible)
- Verify controller ↔ HMI communication
This step alone can prevent unnecessary
$1,000+ replacement mistakes.
Repair vs Replacement: What’s the Best Option?
When hardware failure is confirmed:
Option 1 — Replace Pendant
- Fastest recovery
- OEM or compatible units available
Option 2 — Repair
- Replace screen / cable / PCB
- Lower cost but longer downtime
Option 3 — Refurbished Unit
- Cost-effective
- Tested and ready to deploy
For production-critical lines, always
keep a backup pendant.
Advanced Diagnostics (For Engineers)
- Check controller LED indicators
- Use SSH (if enabled) to verify system boot
- Inspect UR log files
- Test communication channels
- Verify grounding / shielding (EMI issues)
Helps identify:
- Control box failure
- Pendant failure
- Software corruption
FAQ
Q1: Why is my UR teach pendant
not working?
Most commonly due to power issues, cable
damage, or software failure.
Q2: Can I run a UR robot without
a pendant?
Yes (remote mode), but setup and
troubleshooting usually require it.
Q3: How do I confirm if it's the
controller or pendant?
Swap with a working pendant—fastest and
most reliable method.
Q4: What software does UR use?
PolyScope, the main interface for
programming and operation.
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