Technical information

The long arm axle bolt rotated on the set screw. In addition, there was a problem with the

backup battery in the controller. All motion profiles and control law coefficients that

remain constant are burned to the EEPROM along with the rest of the compiled source

code. However, constants that can be changed, such as positions for the presets modified

by operators, are stored in RAM. The RAM is preserved through system power and the

internal battery during power outages. Since the DRV is not run continually, the battery

load is higher than the controller manufacturer had designed for. Therefore with a

drained battery, when the system is shut down the desired positions for the presets are

lost. The next time the system is initialized, the preset positions are not preserved.

However, information always resides at memory locations, whether it is known or

unknown there is always a sequence of zeros and ones. The result is an unpredictable

motion profile upon commanding a preset requiring the operator to cancel the preset

motion, by moving the joystick off-center or hitting the emergency stop, before damage

can occur.

Fix

Set screw should be removed, the axle bolt seating hole dressed, and a new set screw

installed. For the RAM backup battery the solution was to add an external battery pack

that can be readily serviced and has an extended lifetime. The presets can be easily set by

the operators after the batteries are replaced.

May 2002

Report

The turntable is not rotating.

Problem

The turntable motor is not responding. Hydraulic valves were swapped to verify that the

motor was failing to operate.

Fix

The motor was replaced.