Fluke Biomedical 07-494 - Manual (Page 29)

6
Maintenance and Troubleshooting
Performance Verification (Calibration Constancy)
6-3
4. Periodically (every 6 months) or when a serious discrepancy occurs, repeat Steps I through 3 to
determine which piece of equipment is in error.
If the kVp meter suddenly produces different results
from previous tests on only one machine, then
there is a strong probability that the kVp Meter is
operating correctly. If all of the x-ray measurements
suddenly change, then the kVp Meter may not be
operating correctly.
6.4 Verifying Supply Voltages
Troubleshooting the kVp meter consists of verifying the supply voltages.
Equipment recommended for troubleshooting the kVp Meter includes:
1. A digital voltmeter (Fluke Model 77 or equivalent).
2. A storage oscilloscope (Tektronix Model 2430 or equivalent).
Use the following procedure:
1. Connect the DVM negative lead to TP4 (circuit ground).
NOTE
NOTE
All measurements will be made with reference to
TP4.
2. Apply power to the unit under test.
3. Test for the voltages listed in Table 7-1.
3. If any of the voltages cannot be verified, replace the faulty component (refer to the comments
column of Table 7-1).
The waveforms in Figures 6-2, 6-3, and 6-4 are provided for reference.
Table 6-1. Test Point Voltages
Test Point Voltage Comments
TP3 2.4 to 3.2 V Derived from U101 on VRM board.
TP5 -5.0 to 6.0 V Derived from U101 on VRM board.
TP10 1.2 to 1.6 V Derived from voltage divider R22, R23