"Roughing, System Pressure Wait" Pumps wont work

I have a Varion 979 now Agilent.  I have the pumps DS 302 and SD-451 attached.


When I turn on the unit the roughing pump usually starts as the unit warms up.  Today the roughing pump did not start screen just says "Roughing System Pressure Wait".  Tried to engage the system to measure a leak rate to engage the Turbo Pump; still nothing.  All seems dead down below.


Shut down the unit and turned back on, still nothing.  Pushed the fuse resets, redid the power cords, check switches on pumps and still dead pumps.  What gives?

  • This could be any of several things, depending upon whether you have a version one or two 979. Since you have a SD451 roughing pump, I assume you have a version one, the one with fuses in the back instead of circuitbreakers. First, I would check the receptacle on the leak detector, and ensure you have the roughing pump (the one that connects to the side of the leak detector)plugged in to the roughing receptacle. Many people get these switched by mistake. The backing pump attaches from the bottom of the leak detector, the roughing pump to the side.


    Next, I would check the system pressure thermocouple. Ohm out between the pins for continuity. If the tc is open, the system pressure will not allow the continuation of the start-up sequence. This is an inexpensive part.


    Start there. If that doesn't fix things, call 800 882-7426, option 5, and ask for george (the good-looking one!), and we can explore other options.

  • Hi George,


    I think I have version two.  I have no fuse access on the back where it plugs in.  I have attached three pictures for identification.   Let me know if this changes anything.






Reply Children
Was this helpful?