Applies to

• VLF Platesetter
• VLF Trendsetter
• ThermoFlex

Problem

Perform the following steps in order until you have identified the cause.

Solutions

1. See Notes on drum balance.

2. Ensure all NVS drum parameters are set properly for the engine size.
   The defaults are for 5080 machines. Check the drum module for 5880 values of the parameters or check Default values for NVS drum parameters per engine size.

• If the error occurs during plotting, check the velocity control parameters (pgv, igv, dgv)
• If the error occurs during loading/unloading, check the position control parameters (pgp, igp, dgp)
• Check the drum acceleration parameters (vacc and pacc):

• set drum vacc 7 (5080 and 5880 engines)
• set drum pacc 5 (5880 engine)
• set drum pacc 2 (5080 engine)
• Reduce further if problem persists. Decreasing the parameters increases machine cycle time.

• Parameters are optimized for the published design drum belt tension. Earlier machines may have slightly customized parameters. Do not overwrite the values without recording them first

3. Ensure that the drum drive motor pulley is not slipping and that the key is in the motor shaft keyway. Place a line across the end of the pulley and motor shaft to tell if it is slipping on the motor shaft.

4. Ensure that the drum drive belt is not damaged, dirty or rubbing against the belt cover or its assembly screws. Check the belt tension. Make sure that the belt is not too loose, and that the motor pulley is squared to the drum against the leading edge clamps. (Unless the belt is very slack, the machine is not very sensitive to belt tension when the control parameters are set properly). See Adjusting the drum drive motor belt

5. Decrease the verbose settings:

• set verbose all 0
• set verbose xxx 0
• Enter last command for every module xxx. The command set verbose all 0 does not override active settings of the individual modules. (A value of 1 is generally okay.)

6. Perform a basic drive system test to check the power supplies, cables, motor and drive amplifier.

• Enter the command drum spin 50 c to spin the drum without the encoder control loop.

If the command returns an error, check the power supplies, drive amplifier, all cables and connectors, and the motor. See VLF main drive amplifier for a photo of the drum drive amplifier (13-3591), block diagrams and connector pinouts.

Check that pin 1 on connector J3 is +5V and pin 5 is ground. Check this at the drum drive motor. If the 5V supply is not there, the power supply PS1, cables or connectors may be damaged or disconnected.

• Enter the command drum spin 100. Wait for the drum to reach speed, and enter the command plot on.

If an error occurs, the problem is related to the encoder. See encoder checks below.

If the engine passes the test, bang the engine after issuing a plot on command to get an idea of how robust the drum spin is.

• See color="#0000FF">Servo Amplifier Fault.

7. Check the encoder and MPE.

• Optical encoder cleaning procedure

   

• Checking the optical encoder

  at the MPE test points

• Checking the PLL lights on the MPE

  on the MPE to eliminate the encoder board and cable as the cause.

If the signals are not okay at the MPE, but are okay at the encoder board, the cable between the encoder board and the backplane (TE-BP) is faulty. Replace the cable (VLF Platesetter and VLF Trendsetter: 10-3172A).

• Optical Encoder Alignment Procedure

If the encoder board cannot be adjusted color="#0000FF">:

Check the +5V power at the encoder block at pin 11 of U3 (>+4.6V). If the supply is low, replace with the new version regulated board.

• The board may need replacing.
• The machined mount casting may need replacing.
• The drum bearings may not be pre-loaded properly on the drive end.
• The disk may need replacing due to damage or excessive runout.

If the power, encoder tach signals, and PLL lights are all okay at the MPE board, replace the MPE.

8. Drum drive amplifier torque test:

• Test the drum motor drive amplifier using the Drum torque test
• See also color="#0000FF">Drum "spin" is rough and noisy.
• If the problem persists after the drum drive amplifier has been replaced and all cables and connections have been checked, replace the drum motor.

9. Check the drive amplifier hall LED test

• Enter the command drum spin 3 and look at the yellow hall LEDs on the main drive amplifier. Compare to the normal sequence below.

• If either all LEDs are off or all on at the same time, there is probably a damaged or loose connector or cable between J3 and the motor or no 5V power between J3 pin 1 and 5 (or damage) to the hall isolation daughter board within the drive amplifier. The hall isolation daughter board is a small board 3 cm square underneath the drive amplifier board with the 3 yellow LEDs mounted to it, and is located between J3 and J1. If you can see more than 1 or 2 mm of the daughter board connector pins re-seat this connector, check the cables, pins and connectors of J2 and J3.

• If the problem persists, replace the drive amplifier.

• If the problem persists after the drum drive amplifier has been replaced and all cables and connections have been checked, replace the drum motor.

10. Increase the NVS parameter drum maxdiff to 1000 from the default 200 if the error reported is "Hall velocity does not match encoder velocity". This sets the acceptable difference between the velocity reported by the motor hall sensors and the drum encoder.

11. See Drum: Position Error - drum rotation blocked or PID gain setting wrong (6024)

Notes

Drum balance should be activated for troubleshooting these problems. If the balance weights are disabled and the drive amplifier or encoder setup is marginal, it may cause an error. If the balance is disabled because it was causing problems, the weights must be manually positioned to perform the tests.

Marginal drum amplifier or encoder problems are most likely to occur after a machine reset, or after the operator has removed a plate from the drum and repositioned the TEC clamps at the park bars. Small plates result in the TEC clamps being placed approximately opposite to the LEC clamps. The balance weights are then placed opposite the TEC clamps, i.e., near the TEC park position. If the plate is removed by the operator for some reason, the operator must reposition the TEC clamps at the park position. The combined imbalance of TEC clamps and the balance weights positioned at or near the TEC park position may be too large to allow the drum drive to recover the weights without issuing an error.

To recover from this situation manually (not with the diagnostics terminal), move the balance weights to a static position, or move them exactly opposite the TEC clamps park position. Put the LEC down and move the center of the bronze weights at each end to be facing straight up.