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Too Cold and Too Hot Sensors for HP 5971 and HP 5972

HP 5971 and HP 5972 Mass Spectrometers have difussion pumps and on the frame of the diffusion pump are two sensors.  A   Too Cold Sensor, the bottom (white wires) and the Too Hot Sensor, the top (red wires).   The signal from the sensors report to the startup and run electronics of the Power Distribution Board.

Testing these sensors is easy to do.

A little common sense will go a long way to trouble shoot diffusion pump sensor errors.

If the error is  "Too Cold", check to see if the diffusion pump is running and hot.  Be very careful, a hot pump is VERY HOT and will cause injury.   If the diff pump is cold then the error is correct and there is likely a problem with the diffusion pump heater or the mass spec electronics.  Contact us for help.  If the diff pump actually is HOT, then the sensor is likely bad.  We replace  A LOT of   Too Cold sensors.

If the error is  "Too Hot", check to see if the diffusion pump is running and hot.  Be very careful, a hot pump is VERY HOT and will cause injury.   If the diff pump is hot, check to see if the cooling fan is running.  If not, contact us for a replacement fan.  If the fan is running, it is possible that the fan is not running fast enough and requires changing.  To test for this condition, get an external oscillating or box fan and blow it directly at the diffusion pump.  Wait 30 minutes or so.  If the "TOO HOT" error goes away, you know that the fan is not doing its job.  If the Too Hot error persists, even with a cold diff pump, change the Too Hot sensor.   We   RARELY replace Too Hot sensors.

Contact us directly for new sensors or if you have any questions.

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HP 5971 and HP 5972 Diffusion pump trouble shootin...
Connecting a rough pump to your mass spectrometer