Applies to

• Platesetter 3244
• Trendsetter 3244
• VLF Platesetter
• VLF Trendsetter

Description

Causes

• Bad connections between Hall Effect Sensors and MPE

Solutions

Bad connections between Hall Effect Sensors and MPE

The ultimate cause of this error is that the MPE sees pulses derived from the Hall effect sensors as having too short a period (i.e. the frequency too high). The signal originates in the drum motor Hall effect sensors, passes into the Drum Drive Amp at J3 (J3 also provides power to the Hall effect sensors), then the 3 hall effect signals are combined in the drive amp and pass out through J2 (flat ribbon) to the card cage back plane. From there they pass through to the MPE. If there are any bad connections along the way, spikey noise pulses may be added to the pulse train. These spikes cause the MPE to think that the motor is overspeeding.

Check that all hall effect signals are working by slowly rotating the drum and monitoring the yellow LEDs in the drum drive amp.

If a breakout box (10-3732A) is available, connect it between the backplane and the cable and monitor the tach LED. If there is a scope available monitor the Tach signal (TP7). (Note: there is a minor bug on the board. TP6 does not connect to "fault" as indicated.)

1. Check that there is 5V power on J3-8 relative to J3-10. (See info on hall sensor)
2. Check that the drum motor is grounded.
3. If the drive amp yellow LEDs appear okay, replace the following parts, in this order:
   1. Ribbon cable from J2 of drive amp to backplane.
   2. Power cable from the drum drive amp to the motor (for VLF also replace the signal cable to the motor.)
   3. Drum drive amp
   4. MPE
   5. Backplane (this has failed 3 times in the past, no matter how unlikely it seems.)
   6. Drum motor
4. If the drive amp yellow LEDs appear faulty, replace the following parts, in this order:

1. Power cable from the drum drive amp to the motor (for VLF also replace the signal cable to the motor.)
2. Drum drive amp
3. Drum motor

NOTE: See Understanding dependencies on Hall Sensors and Encoder.

See also