9600 Service Manual - gmecorp-usa.com

mA Generation 13
MA TROUBLESHOOTING
MA CONTROL
With 80 kV @ 5 mA selected in the manual fluoro mode and no X-ray switch pressed,
you should measure approximately -1.7 VDC on TP8 of the X-ray Regulator PCB. This
voltage should go more negative as the mA setting is increased and less negative as the
mA setting is decreased. No X-rays are necessary to perform this check.
The ratio for TP8 is approximately -350 mV/mA in the fluoro mode and approximately -
70 mV/mA in the film mode.
MA DRIVE
In the manual fluoro mode with no X-ray switch pressed, the FILDRVA and FILDRVB
input signals to PAL U10 (pins 5 & 6) on the X-ray Regulator PCB should be out of
phase with a frequency of 2.5 kHz. The duty cycle should decrease as less mA is
selected and increase as more mA is selected. The FILDRA and FILDRB output signals
from PAL U10 pins 12 and 13 should do the same. No X-rays are necessary to perform
this check.
FILAMENT REGULATOR
In the Manual or Auto Fluoro mode with no X-ray switch pressed, you should measure
approximately +4 VDC on U27-6 (FIL B+ CTRL) of the X-ray Regulator PCB and
approximately +160 VDC out of the filament regulator on R8 (or Q4 collector) of the
Generator Driver PCB. The FIL B+ SNS voltage on U27-1 of the X-ray Regulator PCB
should also measure approximately +4 VDC. All three of these voltages should vary
during an exposure.
The ratio for FIL CNTRL is approximately 1:40, for every +1 VDC on TP10 of the Analog
Interface there should be approximately +40 VDC out of the filament regulator.
MA SENSE
During an 80 kV @ 5 mA Manual Fluoro exposure, you should see mA voltage pulses
on TP7 of the X-ray Regulator PCB with an amplitude of approximately +950 to
+1200mV (using an oscilloscope). However, the average DC voltage component of
these voltage pulses on TP7 should be approximately +125 mVDC (measured with a
DC Volt meter). The voltage on TP6 should be approximately +125 mVDC and TP11
(MA Measured) should be approximately +625 mVDC. All of these voltages should
increase as actual tube current (mA) increases and decrease as actual tube current
(mA) decreases.
The ratio for TP6 and TP7 is +40 mA/VDC in both Fluoro and Film modes. The ratio for
TP11 is +8 mA/VDC Fluoro mode and +40 mA/VDC Film mode.