APX 525/625 Generator Revision C Diagnostics
©
2005 Del Medical Imaging Corporation
7/5/2005 Page 166
If the anode or cathode feedback voltages go outside of the window value of 1.3
VDC to 7.0 VDC (representing 13 to 70 kV for either the anode or cathode) one of
the comparators will be tripped. If either comparator is tripped during an exposure
attempt, the fault condition is latched and cannot be cleared until the unit is turned
off and back on again. When this latch is engaged, the following events occur:
• kV Drive Signals are blocked by the K1 relay on the motherboard (to
terminate inverter operation)
• A fault signal is sent to the Logic PCB, which terminates all “exposure”
signals
• The Logic PCB sends a fault signal to the console
There are many possible causes for kV faults. This section of the user manual
provides a method for checking specific points to determine specific cause.
There are two basic categories of causes for kV faults:
• Category I - Consistent kV Fault: This is a list of possible causes for which
a kV fault occurs consistently with every exposure.
• Category II - Intermittent kV Fault: This lists the possible causes for an
intermittent kV fault.
Category I - Consistent kV Fault
Check for open inverter fuse.
1. Turn off power to the generator
2. Wait 5-10 minutes for the inverter capacitors to discharge
3. Verify with a voltmeter that there is 0 VDC across an inverter capacitor
4. Remove F1 fuse
5. Use an ohmmeter to determine if the fuse is open
Note: If this fuse continues to open, especially on higher mAs exposures, check the
capacitance of the commutation capacitors or the SCR hold-off time described in this
manual.
Also see “AP Generator Fuse Blowing Possibilities” in this section.
Check for a kV Imbalance greater than 7kV
An imbalance between the anode and cathode feedback waveforms can be caused
by:
• improper adjustment of the balance resistor at the rear of the power
module
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