Calibration
Stability Pot (R83) Overshoot Adjustment
CAUTION: Failure to perform this adjustment may cause kV overshoots and X-ray tube arcing.
1. If you are installing a new HVSR PCB, turn R83 on the High Voltage Supply Regulator PCB fully clockwise (10 turns max),
and then turn it counterclockwise about one turn. This provides an approximate starting adjustment. Otherwise, skip this
step.
2. Connect channel 1 of the oscilloscope to TP21 (KV_SEN_TP) on the High Voltage Supply Regulator PCB and channel 2 to
TP40 (HI_MA_SEN).
3. Select 15 or 30 fps and 15 or 30 pps on the Workstation. While taking an HLF X-ray, set the kVp for 40 and adjust mA to 11.
Observe the kVp signal at TP21 (KV_SEN_TP) looking for kVp overshoot on the leading edge of the kVp waveform. If kVp
overshoot exceeds 400 mV, adjust R83 to reduce it. Repeat this procedure, increasing the kVp by 10 each time until you
reach 120 kVp.
4. While observing the oscilloscope, adjust R83 for about 400 mV of overshoot--This represents about a 5% overshoot. See
waveform in following illustration.
15
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