Trouble Shooting

If the Pulsar Fails to Trigger:

1. Check to see if the Trigger Transformer is ON and the ready light is lit.
2. Check to see if the correct Nitrogen pressure is being used.
3. Determine if the trigger pulse causes the H.V. lamp on the Trigger Amplifier to blink.
4. Check to see if the Trigger Amplifier is operational:
   • disconnect the trigger cable from the pulsar.
   • attach a clip lead between the outer shell of the lead and a good ground.
   • Send a trigger pulse to the Trigger Amplifier and check for a discharge.
   • if there is no discharge or the Trigger Transformer discharges inconsistantly, replace it.
   • Remove the Base Adjust Assembly and connect only the trigger cable from the Trigger Transformer. Attach a clip lead to the trigger pin and place it within1/8 inch of the ground pin.
   • Send a trigger pulse to the Trigger Amplifier and check for a discharge.
   • if there is no discharge or the Trigger Transformer discharges inconsistantly, contact Field Emission Corperation.
5. Check to see if the trigger ball is making contact with the threaded shaft that is supporting it:
   • Remove the Module Column from the Pulsar.
   • Remove the Trigger Module fron the Column.
   • Use an Ohmmeter to measure the resistance between the Trigger Ball and the Threaded shaft.
   • If the Resistance is infinite or extremely high, the Trigger Ball should be removed from the Threaded Shaft and the contact points should be cleaned.
6. Check to see if the Trigger Ball is operational:
   • Connect the Trigger Cable to the Threaded Shaft.
   • Apply a trigger pulse to the Trigger Amplifier and look for a discharge between the inner pin and the outer case of the Trigger Ball.
   • If the discharge occurs in the Trigger Ball instead of on the face, replace the trigger ball.
7. Check to see if there is a Freon Leak:
   • A good indication of a Freon Leak is the color of the spaark balls. If they look copper-plated then there is probably a Freon Leak.
   • Check for the Freon Leak which may be where the "O"-ring seals the joint between the Pulsar Module Chamber and the Pulsar Case.
8. No reading on Charging Voltage meter when High Voltage Control is turned up; High Voltage On lamp fails to light; Interlock Open lamp lights:
   • Check for an open interlock by momentarily pressing the Override Interlock switch as the High Voltage on button is pressed; the fault is in the interlock circuit. Correct the fault before charging the Pulsar.
9. Charging Voltage meter shows little or no voltage as High Voltage Control is advanced; High Voltage On lamp goes out, High Voltage Ready lamp lights:
   • Check the interplay between the high voltage meters on the Magnetic Field Control paanel and the High Voltage Power Supply Control panel.
   • Check for a short circuit in the charging circuit:
   • if a constant charging current is noticed when the High Voltage Control is advanced there is a short.
   • Determine where the short is.
     • Disconnect the high voltage to the Pulser at the RFI Housing H.V. Input. Check for a short.
     • A cable may be shorted. Check the cable and replace it if it is found to have a short.
     • If the short does not exist in either the Pulser or the charging cable, the short circuit exists within the Oil-Insulated High Voltage Power Supply Rectifier Tank. Check by disconnecting the charging cable at the supply tank and advancing the High Voltage Control. CAUTION: After base adjust assembly removal. Aalways discharge the Module Column prior to removing the Column. The D-C breakdown leakage of a faulty module may be as high as 10-15 kV, which allows a charge to remain on the modules.
   • If the short circuit is isolated to the Pulsar:
     • Depressurize the Pulsar Module Chamber.
     • Remove the Modules.
     • Short the two outer concentric on the column base plate.
     • Check for resistance between these two rings and try to detect a short.
     • If the ohmmeter couldn`t find the short, use the High Voltage Power Supply: connect the ground to the middle concentric ring and the high voltage to the outer ring. Apply high voltage and slowly increase until leakage current is observed on the milliammeter of the High Voltage Power Supply Control panel.
   • Check to see if any of the Modules are faulty:
     • Remove the two tie-rod nuts at the top of the Module Column.
     • Pry apart and seperate the Module column, at the center of the column enough to break the connections between the Modules.
     • Repeat the check for leakage as outlined in previous paragraph. If leakage is still present, the faulty Module is in the lower half of the column.
     • Repeat the second step, seperate the lower half at the centerfirst quarter section. If no leakage is indicated, then the faulty Module is in the second quarter section.
     • Repeat this process of elimination until the faulty Module(s) are located. (Caution: Short oout the spark gap of each module before handling.)
   • Charging Voltage meter shows normal voltage rise, but Pulsar prefires before full voltage is reached:
     • Be sure to use correct air pressure.
     • Check all of the charging cable connections for carbonization due to arcing.
     • Turn on High Voltage Control to zero. Note whether the H.V. lamp on the Trigger Amplifier blinks either occasionally or repeatedly. This "Blink" indicates that the Thyratron tube in the Trigger Amplifier has fired. If blinking is noticed, replace the tube. If that doesn't work, check for trouble in the Trigger Amplifier Circuits.
     • Recheck system grounds to be sure they are all tight.
     • A strong electro-magnetic signal, such as from a nearby radar, may cause the Pulsar to fire prematurely.
     • Be sure that large fluctuations in line voltage are not present.
     • Purge the air pressure system by disconnecting the air line at the RFI Housing and then reconnecting it after all the air has escaped.

If there is Jitter or Erratic Triggering: (Jitter: The unintentional displacement of trigger or X - Ray pulse along the time axis.)

1. To minimize the possibility of Jitter:
   • Find the operating point on the Air Pressure vs. Pulsar Charging Voltage graph.
   • The operating point should be closer to the self-fire curve than to "minimum trigger" curve.
2. Recheck input sensitivity at Trigger Amplifier.
3. If jitter consists of a pulse delay on the order oof 10 microseconds, it is possible that Freon has leaked into the spark gap column. remove the Module Column.
4. Check and see if the Trigger Trransformer is connected correctly.
5. Check for proper trigger waveform at Trigger Amplifier input.
6. Check for proper waveform at the grid of the Thyretron tube in the Trigger Amplifier.
7. Check the trigger circuitry cable connections and/or try replacing the Thyretron tube in the Trigger Amplifier.