How To Test The Tuttnauer Water Pump Solid State Relay

Troubleshooting Guides for all Tuttnauer "E" Series Autoclaves - Including Models 1730E, 1730EK, 2340E,2340EA, 2340EK, 2340EKA, 2540E, 2540EA, 2540EH, 2540EHS, 2540EK, 2540EKA, 3870E, 3870EA, 3870EH, 3870EHS, EZ9 & EZ10)

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Get Ready To Look For A Short In The Solid State Relay


  • Unplug the unit From The Wall
  • Remove the Outer Cabinet
  • Label and then remove the four wires connected to the Solid State Relay

Using an Ohmmeter - Test The Relay For A Short Circuit

  • Check for a short circuit between terminals 3 & 4 and 1 & 2 and 3 & 1 and 4 & 2 and 3 &p; 2 and 4 & 1.
    Make sure there are no direct shorts. If a direct short is found in the Solid State Relay, replace it

Using An Ohm Meter - Test The Meter For An Open Circuit


Open Circuit Explained
An "Open" Circuit Is Defined as Not Continuous: Current Doe Not Flow Thru It


  • Check for an open circuit (testing for continuity) between terminals 1 & 2
  • Be sure to reverse the meter leads and check in the opposite direction. Repeat the procedure for terminals 3 & 4. If an open is found (not continuous), replace the Solid state Relay

Get Ready To Test The Voltage

  • Reconnect the wires to the four connectors of the Solid State Relay
  • Plug the unit into the Wall Outlet
  • Turn the unit on
  • Make sure the autoclave is sitting idle with no cycle running. If necessary, abort any cycle that may not have been completed
  • Take a DC voltage reading from terminal 3 on the Solid State Relay to ground
  • In checking the Water Pump circuit, this device should also be in the OFF mode, with a voltage reading between +10.5 and +12 volts DC
  • Repeat this procedure with terminal 4 and you should have the same reading. A good reading indicates that the Solid State Relay is not turned on
  • If terminal 3 does not read between +3.5 and +5 or +10.5 and +12 volts DC, check if the Power Supply is properly supplying these voltages
  • If terminal 4 does not read the correct voltage, unplug the unit and remove the wire on terminal 4
  • Turn the power back on and recheck terminal 4
  • If the reading is still not correct, replace the Solid State Relay
  • If the reading is correct, check continuity between the terminal #4 wire and JP15 On The Ajunc Board unplug the unit when taking this reading If continuity checks out, there is a Control Problem
  • With the Water Pump ON and running, there should be a reading between +10.5 and +12 volts DC from terminal 3 to ground and a reading between 0 and 1 volt DC from terminal 4 to ground
    • If the reading at terminal 4 does not show a reading of between 0 and 1 volt when the Water Pump is ON, check continuity between terminal 4 and the appropriate Ajunc board connector
    • If continuity is good, there is a Control Problem
    • If the reading at terminal 4 is between 0 and 1 volt and the Solid State Relay is on. The control side of the Solid State Relay is okay and the problem may be on the load side