APX 525/625 Generator Revision C Service Adjustments
©
2005 Del Medical Imaging Corporation
7/5/2005 Page 147
9. Remove the mAs meter from the circuit and reconnect the “MA+” wire to its
original position in the terminal strip on top of the high voltage transformer.
Ensure that this connection is secure.
10. Remove the mAs Regulator Board from the extender card and return the board
to its original position in the card cage.
mA Fault Calibration
The filament over-voltage limit circuit monitors the voltage applied to the filament
transformer and ultimately, the x-ray tube filament. This circuit turns off the filament
supply when there is either a component failure or a maladjustment
Before attempting this adjustment, observe the relay K2 of the power supply board.
This relay will be energized during normal operation. If the relay de-energizes even
with very low generator power settings, this may indicate component failure. If the
relay remains energized with low power settings, but trips at high power settings, this
may indicate that an adjustment is necessary. When the relay trips, the error
message will be: ‘mA fault’.
If adjustment is necessary:
1. Place the mA/Rotor Board 124-0095G1 on the extender card.
2. Connect the negative lead of a DVM to the mother board ground point (TP-12).
3. Connect this positive lead of the DVM to U23, pin 10 on the mA/ rotor board.
4. Turn the generator on.
5. Set the generator to manual mode, tube one, large focus, 70 kV, 11 mAs,
minimum time.
6. Press and hold "Prep" while adjusting R57 of the "mA/Rotor" board for 0.8 VDC.
If mA faults occur, turn pot CW 1/8 of a turn at a time to reduce value. Press
reset and then prep again to assure that the fault doesn’t reoccur.
7. If the fault does occur, rewire the filament cable for 0.2 ohms according to the
figure on the next page.
8. Perform pre-heat mA calibration for small filament.
9. Check performance of the generator at all the small focal spot mA stations.
10. If no mA faults ocurr, turn the generator OFF, and return the mA/Rotor board to
the card cage. Procedure is complete.
11. If mA faults occur at any of the mA stations, repeat steps 7-10 for next lower
resistance value – 0.1 ohms, 0.05 ohms. See figure on the next page.
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