GENERAL RULES FOR TROUBLESHOOTING BY COMPONENT SUBSTITUTION

 

Always make sure cable connectors are fully inserted into their mates and that the threaded collars are tight

 

  1. The most likely cause of a system malfunction is a defective tube head cable.  The cable alone may be defective or the defective cable may have damaged other system components.
    1. If a system is malfunctioning, never take a good control unit or tube head from another working system and try it on the malfunctioning system without first substituting a known good tube head cable.
    2. If the system still does not work after substituting the good cable, do not then assume the original cable is good; set it aside.
  2. After insuring a good cable is installed, the next component to substitute is a known good tube head for the questionable one.
    1. When testing the system after substituting the good tube head, always start in the Operate Mode with a 0kV and 0mA on the set line.  After pressing the x-ray ON, first advance the mA to 5.0mA and then the kV one kV at a time. mA should be flowing and at 5.0 by the time 25kV is reached.  Continue to advance the kV up to 100kV.  If no problems are encountered up to 100kV, warm the tube head up using the >30 days autowarm mode.  If problems occur at low kV do not keep trying to advance the kV.
    2. Do not assume the original tube head is good.
  3. If malfunctions still occur, substitute a good Control Unit.  Start in the Operating Mode and advance mA and kV as in Step 2A.
  4. The system should be operating properly now if all of the components used for substitution were good.
    1. Now check out the original tube head by putting it back on the system.  Again start testing in the Operate Mode with 0kV and 0mA set in on the control unit.  After pressing the x-ray ON, advance the mA to 5mA and the kV one kV at a time. mA should be flowing and at 5,0 when 25kV is reached.  Continue to advance the kV up to 100KV.  If problems occur at low kV, do not keep trying to advance the kV.  If no problems are encountered up to 100KV, auto-warm the tube head at the >30 day rate.
  5. Continuity test cables pin on one end to corresponding pin on other end and from each pin to all the other pins and the shell on the same end of the cable.  BEWARE: a cable may be good laying in one position but be defective in another position.

 

PROBLEM DIAGNOSIS SUGGESTIONS

  1. Repeated Are Detect Message
    1. Low Line Voltage - Line voltage below 100 volts (continuously or intermittently) causes the x-ray generation to stop and the ARC DETECTED message to be displayed.  Measure line voltage under lead.  Use power source greater than 100 volts.  Don't use extension cord.
    2. Insufficient Warm Up - Tube reactions can result from inadequate warm-up causing the ARC DETECTED message to be displayed.  Manually warm up using the procedure described in NOTES on Page 4-6 of T.0 33B33-31-11.
    3. Defective Components - Return to Depot for repair.
  2. Interlock Flow Message
    1. Interlock Open

                                                              i.      Interlock jumper missing

                                                            ii.      Defective cable connecting external interlock/warning system

                                                          iii.      Defective external interlock system

    1. Defective Control Unit - A defective or incompatible external interlock system can damage the Control Unit by shorting pins A or B to ground or by feeding external voltages into Pins A or B. Check for shorts to ground on Pins A and B of the cable and also for the presence of voltage on Pins A and B of the cable.  Try disconnecting interlock cable and using supplied interlock jumper to isolate problem.
    2. Insufficient Coolant Flow

                                                              i.      Check and clean filter in cooler

                                                            ii.      Check for clogged hoses or improperly mating hose fittings

                                                          iii.      Continuity check cooler cable

                                                           iv.      Bad flow switch in cooler - replace flow switch

  1. Circuit Breaker Trips
    1. Trips immediately on application

                                                              i.      Line voltage in excess of 130 volts - measure line voltage.  Use power source, less than 130 volts.

    1. Trips after one to two second delay

                                                              i.      Short in cooler or cooler cable.  Substitute different cooler or cooler cable.  Continuity test cable.

                                                            ii.      Defective control unit

                                                          iii.      Intermittently high line voltage in excess of 130 volts

    1. Trips when x-ray ON switch is pressed.

                                                              i.      Defective control, tube head, or tube head cable.  Continuity test cable.

  1. Temperature/Pressure Message
    1. Low tube head gas pressure or high anode temperature - See T.O. 33B3-3-31-11.
    2. Defective tube head cable - Continuity test cable or substitute with known good cable.
    3. Loose or Defective Tube Head Anode Thermostat - Separate two halves of small white connector attacked to wire leading out of tube head pressure switch and down the side of the tube head.  Measure the resistance between the connector half on the wire leading down the side of the tube head and the bare 10-32 screw head on the tube head end plate.  The resistance should be less than 5 ohms.  Look for breaks in the wire, tighten or replace thermostat.
    4. Defective Tube Head Pressure Switch - Continuity test pressure switch by measuring resistance between half of white connector that is attached to pressure switch and Pin A of tube head end plate connector.  Resistance should be less than 3 ohms.
  2. Repeated Excess kV Message
    1. Defective tube head cable, control unit or tube head.  Substitute good components to isolate problem.
  3. X-Ray Switch Error Message
    1. Message appears within 3 seconds of switching the mains on.  X-ray ON switch is shorted.  Repair or replace.
    2. Message appears while system is generating x-rays.

                                                              i.      Insufficient warm-up.  Perform manual warm up –See notes on Page 4-6 of T.O.33B3-3-31-11.

                                                            ii.      If re-occurs repeatedly, tube head cable or tube-head may be, defective.

  1. Interrupted Restart Message
    1. Message appears after fault condition has been corrected.
    2. May appear after intermittent fault such as erratic coolant flow, loose thermostat, temperature/pressure conditions, etc.
  2. Black Blocks on LCD Displays
    1. These black blocks are caused by an electrical pulse from a tube reaction interfering with the digital display.  Turn the unit off and then back on and warm up at slowest rate.
    2. If black blocks repeatedly occur, the tube head cable or the tube head may be defective.