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DIGISONDE-4D
SYSTEM MANUAL
VERSION 1.2.11
SECTION 6 - MAINTENANCE 6-29
6:92. If the Control Computer does not beep (signifying successful Power On Self Test or POST) and there is
no video output once a monitor is connected (It may be necessary to Restart the Control Computer as described
in 6:85.) then it is suggested to replace the Control Computer with a spare.
6:93. Assuming the Data Computer is operating, the information displayed on the BIT page accessible from
the BIT tab in the DCART window may provide some assistance in locating a fault.
TROUBLESHOOTING THE POWER INTERFACE BOX
Special Test Equipment: Digital Multimeter
Reference Documents: Power Interface Schematic
Test Components: N/A
6:94. Under normal operating conditions, if a voltage at terminals BT1 & BT2 (nominally 27 – 27.5 volts but
certainly between 22 and 30 volts) is present, this voltage should be conducted by the power MOSFETs in the
box to the output at BT3 & BT4. If not, confirm that the toggle switch on the rear panel of the case is UP and
disconnect the remote switch connector. If still no power shows up on BT3 and BT4 one can further test for
failure of the power interface by bypassing it. Power down the system and connect the outputs on terminals
BT3 & BT4 to the inputs BT1 and BT2. If the system powers on normally when power is restored the Power
Interface is faulty and should be replaced.
TROUBLESHOOTING THE POWER DISTRIBUTION CARD
Special Test Equipment: Digital Multimeter
Reference Documents: Power Interface Schematic
6:95. There are 6 DC/DC converters present on the power distribution card and 7 different voltages produced.
If all voltage indicator LEDs are lit most likely all output voltages are healthy. However, if there is any question
concerning output voltages they can be measured with a digital multimeter. Figure 6-25 shows the power dis-
tribution card, identifying locations to measure its DC/DC converter outputs. With the digital multimeter set to
measure DC voltages, place the positive probe in the location indicated with a red circle or arrow, and the nega-
tive probe in the location indicated with a black circle or arrow to measure each labeled voltage output. The DC
voltages measured should be as labeled in Figure 6-25 ± 10%. The O/X switching output should be 22.7V ±
10% when in O mode and 16.7V ± 10% when in X mode. The following is a description of those measurement
points.
1. +15V output is measured on DC/DC converter DC5 between pins 7 and 5.
2. -15V output is measured on DC/DC converter DC4 between pins 7 and 5.
3. +5V output is measured on DC/DC converter DC3 between pins 7 and 5.
4. +3.3V output is measured on DC/DC converter DC2 between pins 7 and 5.
5. +12V output is measured on DC/DC converter DC1 between pins 7 and 5.
6. -5V output is measured on DC/DC converter DC6 between pins 7 and 5.
7. O/X switching voltage output is measured between regulator VR12 pin 2, and DC/DC convert-
er DC5 pin 4.
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