Indicator Failures; X-Ray On Led Blinking; Shutter Open Led Blinking - GE Medical Systems PRODIGY Service Manual

4.13 Indicator Failures

4.13.1 X-ray On LED Blinking

The amber X-RAY ON LED should glow steadily once it is illuminated, until
the x-rays are turned off. If the X-RAY ON LED blinks while the shutter is open
for a patient scan, the End of Exposure Alarm should sound.
The amber LED is controlled by a comparator on the FOINK Board. This LED
illuminates when approximately 40µA (or greater) of current is passing
through the X-ray Insert. On Spellman system scanners the amber light may
appear to fade out slowly when x-rays are ramped down. This due to the
Spellman power supplies bleeding off current and is not a problem.
If the voltage ramping fails, the High Voltage Power Supplies must be shut
completely off before a second ramping attempt is made. If the amber X-RAY
ON LED turns on momentarily, then turns off for a few seconds before coming
on steadily, the system is having difficulty ramping the high voltage. One of the
High Voltage Power Supplies may be defective.
The SBC does not monitor the Insert current once the proper level has been
reached. Therefore, if the current to the Insert is interrupted, the SBC will not
recognize the problem and will not alert the computer, or terminate the
exposure.
If the X-RAY ON LED blinks once the x-ray high voltage has been set, there
must be a problem in one of the following areas:

4.13.2 Shutter Open LED Blinking

4-140Troubleshooting
• Lines or streaks going transversely across the Alignment Test image
indicate a problem with the AGS, on the Detector Daughter Board in the
detector array. Again, replace parts until a passing Alignment Test is
obtained.
• Troubleshooting tip: if the Alignment test can be run with the Alignment
Aperture on, this will make the test more sensitive as the beam will be
further collimated to the exact size of the detector. Any failures (beam
straying off the detector) will be exaggerated.
• Tube Head Control Cable-The most likely cause of an intermittent
problem in this circuit is a broken wire in the Tube Head Control Cable.
The Red wire is most likely the broken one, as a broken blue or black
wire should blow the MAX Board Fuse. Turn the scanner off and test for
continuity between MAX Board test points TP4, TP5, and TP13.
• MAX Board-The MAX Board may be operating intermittently. Substitute a
replacement MAX Board.
DPX-NT Service Manual (Rev A- 1999)