Loss Of Omi Signal - GE Medical Systems PRODIGY Service Manual

The longitudinal Centent Motor Controller may be the cause of a failure. The
current set voltage should be roughly 9-11 volts at terminal 11 on a properly
operating controller. If this voltage is not correct, replace the Centent
Controller.
The Longitudinal Belt should not be tightened too much or this will cause the
brackets holding the gears to deform at either end of the scanner. When the
belt is properly tightened, it should be possible to deflect the upper and lower
sides of the belt so that they touch within 8 cm of the gears at either end.
The rollers in front and the wheels in back that support the Arm must be
adjusted so that they come into perfect contact with the Longitudinal Rails.
Test them by preventing any wheel from turning and see if the carriage will still
move. By preventing any wheel from turning, it should be possible to slide the
carriage along the rail with one wheel dragging while the others roll. This
indicates that the wheel has not been excessively tightened down.
Adjustments can be made by loosening and rotating the eccentric bearings of
any of the lower wheels.

4.2.3 Loss of OMI Signal

DPX-NT Service Manual (Rev A- 1999)
The longitudinal and transverse Centents are identical, and can be
exchanged. If the problem remains, the Longitudinal Motor should be
replaced.
• Longitudinal Belt
• Drive Wheels
• If the Scan Arm motion is irregular, or scraping noises are heard, the
Longitudinal Mechanics may be binding. This symptom will typically be
detected as a failure by the daily QA Mechanics Test.
If the error occurs consistently after the first line of a patient scan, and the
scanner is moving in the longitudinal direction, then check the following:
• Cause: The Interrupt signal is being lost.
Solution 1: The pulses that normally enter the FOINK board at J (the
black wire at the center of the connector) may have stopped. These
pulses are necessary to keep the FOINK board from sending an interrupt
to the SBC. These pulses can be seen on a FOINK board LED.
For LED location see figure 4-1. Use the DPX-NT service software
(Tools/Diagnostics/Scanner Motion / Motion Commands Tab) to set the
joystick speed to 50 steps, enable the joystick and watch the LED. If the
OMI / FOINK is working the LIght will flash when the Longitudinal Motor
is run. If the LED flashes when the mechanics are engaged, but the error
still occurs, the interrupt was invalid. Check for arcing in the high voltage
system or replace the FOINK and SBC.
If the LED does not flash,
Troubleshooting 4-125