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Outer source heaters are not working on the AutoSpec - WKB80051

Article number: 80051


  • Source temperature readback does not reach the set temperature
  • No "lights" in the outer source when the heater is requested on; set point is higher than the readback


  • AutoSpec Premier
  • AutoSpec Ultima
  • MassLynx


One or both of the source heaters have failed.


  1. Verify that the source and analyzer ion gauges are on and reading the source vacuum correctly.
  2. Set the source temperature setting to a high value (for example, 280 °C).
  3. Confirm that light is emitting from either side of the outer source assembly block.
  4. Open a Telnet window and inspect the 3481200DC1-S Source Control PCB readbacks:
    • Open a Telnet window via the Windows Start/Run menu: 
    • Type "Telnet epc" into the run open dialog box to start and open a Telnet window.
    • Type "rmm" into the Telnet prompt (all lowercase, "r" "m" "m" for rioMainMenu).
    • Specify "3" to access subsystems, specify "4" to access the 3481200DC1-S Source Control PCB, and then specify "3" to display a snapshot of the source control PCB readbacks.
    • Set the source to a temperature higher than the readback and type "3" into the Telnet window to list the readbacks when the heater should be on.
      • A working source heater will show the following:
        • 1503.    SourceHeaterVoltageRb    7.254902 (actual value may differ depending on the temperature difference between the set point and the readback)
      • An open-circuit source heater will show the following:
        • 1503.    SourceHeaterVoltageRb
    • Set the source to 0 and type "3" into the Telnet window to list the readbacks when the heater is off.        
      • A working source heater will show the following:
        • 1503.    SourceHeaterVoltageRb
    • The readbacks above show the 3481200DC1-S Source Control PCB to be electrically functioning, suggesting an open-circuit source heater.
    • Type "999" into the Telnet box repeatedly until the -> prompt is seen.
    • Close the Telnet window.
  5. Vent the source region per standard system operating procedures and remove the outer source assembly.
  6. Using a digital voltmeter set to resistance measurement (0 to 10 Ohms if the scale is manually set), test the short circuit resistance of the meter leads:
    • Touch the test leads together and note the resistance: expect 0 to 0.5 Ohms.
    • If the reading is higher, try new test leads or an alternative digital voltmeter.
  7. Referring to the Outer Source technical reference, circuit measure the resistance through the outer source heater circuit.
    • Measure resistance between pins 7 and 8 on the left-hand side contact rail.
    • Expect a resistance of 0.5 to 1.5 Ohms.
    • If a high or open circuit resistance is measured, one or both of the heaters has failed and will need replacement.
  8. It is good practice to change both heaters at the same time. Order two of M702867AD1 - Source Heater.
  9. Ensure that no shorts are present on the heater connection at the insulated/terminal connection end.
  10. Finalize the build with a repeat resistance measurement as above, and measure the resistance between the ion block and the Focus 1 lens plate.
    • Expect an open circuit, infinite resistance.
    • If a low/short resistance is measured, check for shorts on the filament shields between the ion block and the Focus 1 lens.


See related articles WKB22311 and WKB61442

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