1391B Troubleshooting Guide Objectives This document provides information to guide the user in troubleshooting the Bulletin 1391. Included in the document are LED descriptions and fault diagnosis, general system troubleshooting and test point descriptions. System Troubleshooting Most controller faults are annunciated by the LED diagnostic indicators on the front of the controller. Many system malfunctions manifest themselves through a controller fault. The use of LED indications may aid in identifying servo controller and motor malfunctions. Table A provides a listing and description of the LED indicators. In addition, potential causes are listed. Tables B and C provide a number of common system and servomotor malfunctions and their possible causes Table D provides a listing and descriptions of the Bulletin 1391 test points. WARNING: This product contains stored energy devices. To avoid hazard of electrical shock, verify that all voltage on the capacitors has been discharged before attempting to service, repair or remove this unit. Voltage at terminals 9(+) and 7(-) of TB5 MUST be “0.00” as measured with a standard digital voltmeter or multimeter. Only qualified personnel familiar with solid-state control equipment and safety procedures in publication NFPA 70E should attempt this procedure. Table A LED Descriptions and Fault Diagnosis LED OVERTEMPERATURE POWER FAULT (RED) LED Description The controller contains a thermal switch on the heat sink which senses the power transistor. If the temperature is exceeded the LED will illuminate. The current through the power output transistors is monitored. If the current exceeds a fixed level (greater than 300% of controller rating) the LED will illuminate. Condition/Potential Cause OVERTEMPERATURE LED is illuminated The logic supply (±12V DC, +5V DC) circuits have malfunctioned (fuse blown etc.) or the AC input at TB4-19, 20, 21 is incorrectly wired. The heat sink thermal overload has tripped. One or more of the following may have occurred: 1. The cabinet ambient temperature is too high. 2. The machine duty cycle requires an RMS current exceeding the continuous rating of the controller. 3. The integral fan is not functioning. 4. The airflow access to the controller is limited or blocked. POWER FAULT LED is illuminated 1. The current through any one of the power transistors has exceeded 300% of the controller’s current rating. 2. Malfunctioning power transistor. 3. Shorted load. 4. Excessive winding to case motor capacitance. Faxback Document # 1791 Revision Date 7/28/97 Web location Http://WWW.AB.COM Page 1 of 6 Table A (Continued) LED Descriptions and Fault Diagnosis LED CONTROL POWER (RED) LED Description If the power supply rises or drops 10% from its nominal value, a fault occurs and the LED is illuminated. OVERVOLTAGE (RED) The DC Power Bus is continuously monitored. If is exceeds a present level a fault is sensed, the power supply is disabled and the LED is illuminated. UNDERVOLTAGE (YELLOW) CURRENT FOLDBACK (YELLOW) If the DC Power Bus drops below a present level, a fault occurs and the LED is illuminated. The CURRENT FOLDBACK LED illuminates when the Current Foldback circuitry is operating. Condition/Potential Cause CONTROL POWER LED is illuminated 1. The input line voltage is low. 2. The transformer auxiliary logic supply winding is open. 3. The logic supply(±12V DC, +5V DC) circuits have malfunctioned (fuse blown etc.) or the AC input at TB4-19, 20, 21 is incorrectly wired. OVERVOLTAGE LED is illuminated The logic supply (±12V DC, +5V DC) circuits have malfunctioned (fuse blown etc.) or the AC input at TB4-19, 20, 21 is incorrectly wired. The power bus voltage has exceeded 405V DC 1. The Logic Board is malfunctioning and incorrectly sensing the bus voltage. 2. A vertical axis with insufficient counterbalancing is overdriving the servomotor and causing excessive energy to be returned to the power supply bus. 3. The system inertia is too high causing excessive energy to be returned to the power supply bus. 4. The input line voltage exceeds the maximum controller input voltage rating. 5. The position controller acceleration/deceleration rate is incorrectly set. 6. The shunt regulator or transistor has malfunctioned. 7. Shunt regulator fuse has blown. 8. Shunt regulator resistor not connected to controller. 9. Shunt regulator switch SW1 is set too low. UNDERVOLTAGE LED is illuminated The power bus voltage has dropped below a preset DC value 1. The power contactor (M) has not energized or has dropped out. 2. The input line voltage is low. 3. The shunt regulator circuit has malfunctioned and is placing the shunt resistor across the power bus. 4. The power bus capacitor has malfunctioned. 5. The circuit breaker (MCB) has tripped. 6. The three-phase input line is open. 7. The transformer is providing the incorrect line voltage or has malfunctioned. The logic supplies have dropped 10% below their nominal value 1. The input line voltage is too low. 2. The transformer auxiliary logic supply winding is open. 3. The logic supply (±12V DC, +5V DC) circuits have malfunctioned (fuse blown etc.) or the AC input at TB4-19, 20 21 is incorrectly wired. CURRENT FOLDBACK LED is illuminated The logic supply (±12V DC) circuits have malfunctioned (fuse blown etc.) or the AC input at TB4-19, 20 21 is incorrectly wired. The output current is exceeding its time-current rating. 1. The acceleration/deceleration command from the position controller is requiring peak current for an excessive amount of time. 2. The gain pot is set too high causing excessive peak currents. 3. The machine friction, inertial load and/or viscous loading is excessive. 4. The servomotor has been improperly sized. 5. A short circuit exists across the controller output terminals. Faxback Document # 1791 Revision Date 7/28/97 Web location Http://WWW.AB.COM Page 2 of 6 Table A (Continued) Led Descriptions and Fault Diagnosis LED RUN ENABLE (GREEN) LED Description The application of an Enable signal by the machine position controller will cause the RUN ENABLE LED to illuminate. Condition/Potential Cause ENABLE LED is NOT illuminated 1. 2. 3. 4. The position controller has not enabled the controller. The Enable wiring to the controller is open. The position controller Enable relay/ switch has malfunctioned. The position controller has detected a machine system malfunction that will not allow the controllers to be enabled. 5. Power has not been applied to input transformer. 6. The logic supply (±12V DC) circuits have malfunctioned (fuse blown etc.) or the AC input at TB4-19, 20, 21 is incorrectly wired. ENABLE LED is illuminated, but controller does not enable 1. A controller malfunction has occurred but is not annunciated by the LED indicators. Check the status of the Drive OK output (DROK) relay. 2. A component malfunction exists in the Enable circuit. 3. The circuit breaker (MCB) is tripped. 4. The power contactor has not been energized or has malfunctioned. DRIVE READY (GREEN) This LED is continuously illuminated until a system fault occurs. The controller logic supplies are not operational 1. The logic supply fuses are blown 2. Logic supply AC voltage is missing 3. A controller malfunction has occurred but is not annunciated by the LED indicators (check the status of the Drive OK contacts). DRIVE READY LED is NOT illuminated 1. System fault has occurred. Faxback Document # 1791 Revision Date 7/28/97 Web location Http://WWW.AB.COM Page 3 of 6 Table B General System Troubleshooting Condition Axis or System run uncontrollably Axis or System is unstable Desired motor acceleration/deceleration cannot be obtained Motor does not respond to a Velocity Command Presence of noise on Command or Tach signal wires Possible Cause 1. The velocity feedback, position feedback device or velocity command signal wiring is incorrect or open. 2. An internal controller malfunction exists. 1. Velocity Loop Compensation or Gain potentiometer is incorrectly set. 2. Position Loop Gain or Position Controller accel/decel rate is improperly set. 3. Improper grounding or shielding techniques are causing noise to be transmitted into the position feedback or velocity command lines, causing erratic axis movement. 1. The Current Limit pot is incorrectly set. 2. The Current Feedback Scaling is incorrect. 3. The system inertia is excessive. 4. The system friction torque is excessive. 5. Available controller current is insufficient to supply the correct accel/decel rate. 1. The controller has a malfunction. 2. The controller is not enabled. 3. The power contactor is not energized. 4. Power transformer is supplying the incorrect voltage or none at all. 5. The motor wiring is open. 6. The motor or transformer thermal overload has tripped. 7. The motor has malfunctioned. 8. The motor coupling has malfunctioned. 9. The feedback circuit (motor to controller ) is open. 1. 60 Hz line frequency may be present. 2. 120 Hz from a single phase logic supply may be present. 3. 180 or 360 Hz from other adjustable speed drives may be present. 4. Variable frequency (varies with motor speed) may be velocity feedback ripple or a disturbance caused by gear teeth or ballscrew speeds. 5. Recommended grounding per Appendix B (Publication 1391-5.1) has not been followed. Table C General Servomotor Troubleshooting Condition No Rotation Overheating Abnormal Noise Erratic Operation - Motor locks into position, runs without control or with reduced torque. Possible Cause 1. The motor connections are loose or open. 2. Foreign matter is lodged in the motor. 3. The motor load is excessive. 4. The bearings are worn. 5. The brake is set (when equipped). 1. The rotor is partially demagnetized causing excessive motor current. 2. Motor voltage is exceeding the maximum value. 3. The duty cycle is excessive. 1. Loose parts are present in the motor. 2. Through bolts are loose. 3. The bearings are worn. 4. GAIN setting is too high. 1. Phases A & B, A & C or B & C reversed 2. Sine, Cosine or Rotor leads reversed 3. Sine, Cosine, Rotor lead sets reversed 4. Combinations of 1, 2, 3 Faxback Document # 1791 Revision Date 7/28/97 Web location Http://WWW.AB.COM Page 4 of 6 Test Point Descriptions Table D describes the various test points found in the Bulletin 1391 controller. Refer to Figure 1 for test point locations. Table D Test Point Descriptions Test Point TP1 TP3 TP4 TP5 TP6 TP7 TP8 TP9 TP10 TP11 TP12 TP13 TP14 TP15 TP16 TP17 TP18 TP19 TP20 TP21 TP22 TP23-TP24 TP26-TP27 TP28 TP29 TP30 TP31 Description Buffered Resolver Rotor Signal Tachometer Output (2.5V/kRPM) Demodulated Sine Wave Demodulated Cosine Wave ID PWM Triangle (2.5 kHz, 11Vp-p) PWM B PWM A PWM C PWM Multiplier Triangle (22.5 kHz. 15V p-p) Signal Common +12V DC -12V DC IB Reference IA Reference I Absolute Value Velocity Gain Calibration Buffered Velocity Command Velocity Error Current Limit Calibration (adjust with R148, 3V= Rated Motor Current) Current Command Velocity Loop Response Calibration Velocity Loop Response Calibration Signal Common Current Feedback (Phase B, 2.5Vp-p= Rated Motor Current) Current Feedback (Phase A, 2.5Vp-p= Rated Motor Current) Signal Common Faxback Document # 1791 Revision Date 7/28/97 Web location Http://WWW.AB.COM Page 5 of 6 Faxback Document # 1791 Revision Date 7/28/97 Web location Http://WWW.AB.COM Page 6 of 6