Autoclave Repair Tips

Autoclave Repair Made Simple

Learn About The Tuttnauer 2540M Autoclave Micro Switches

Tuttnauer 2540M Micro Switches

The Tuttnauer 2540M Autoclave has 3 (three) Micro Switches mounted on the shaft of the Multi-Purpose Valve

And the Multi-Purpose Valve is located behind the knob that you turn to select the operation of the autoclave

What are Micro Switches?

Just as their name implies, Micro Switches are small switches that turn something on or off. They have long metal arms, and under the arms are buttons. When the arms are depressed, the button is depressed too….and just like when you flip a light switch on… turns on or off what ever component it is connected to

While the 3 Switches are identical, each is assigned a number (SW1, SW2, and SW3) (their postion on the Multi Purpose Valve shaft and the way they are hooked up (wired) is what differentiates them)

The numbers help tremendously in understanding their function and most importantly, in troubleshooting

You will notice most troubleshooting guides refer to the different switches on the Tuttnauer 2540M Autoclave by their MSW number…. without telling you which switch is which. So it is important you understand the exact switch that is being talked about.

Which Micro Switch on the Tuttnauer 2540M Autoclave Is Which? Here’s your answer

Tuttnauer 2540M Autoclave Multipurpose Valve With Micro Switches Installed

For instance, when following along with Tuttnauer 2540M Troubleshooting Guides a problem with the heat can sometimes be traced to the MSW1 Switch.

By numbering the switches and showing you where they are, you will know exactly which switch it is (the Micro Switch closest to the valve body)

As shown in the diagram above, Micro Switch SW1, is located closest to the valve body, while number SW2 is in the middle, and SW3 is located closest to the front of the autoclave

As you rotate the knob to each position, the valve itself is opened or closed while the three switches are activated or deactivated as needed for the
function called for: FILL, STE (Sterilize), EXH Dry (Vent), and O (off)

Here’s a look at which of the Tuttnauer 2540M Autoclave Micro Switches are activated (turned on) and deactivated (turned off) as you rotate the knob on your Tuttnauer 2540M Autoclave

Valve Position Micro Switch MSW 1 Micro Switch MSW 2 Micro Switch MSW 3
0 Switch Closed Switch Open Switch Open
FILL Switch Closed Switch Open Switch Open
STE Switch Open Switch Open Switch Open
EXH-DRY Switch Open Switch Closed Switch Closed

How To Test the Tuttnauer 2540M Autoclave Micro Switch

Testing the switches is actually pretty straightforward. You simply perform a continuity test. With the unit unplugged and an ohm meter in hand

Tuttnauer 2540M Micro Switch

  1. Locate the “COM” Terminal (COM means Common) and place a probe from your ohm meter directly on the terminal. Then, locate the “NC” (NC means normally closed) terminal and place the other probe on it. Your meter should show be showing continuity. If not, replace the switch
  2. While keeping both probes in place, press down on the arm until the button under it has been depressed. Your meter should now show a “Change In State.” This means when the button is depressed, instead of being continuous, it will now be open – not continuous. If the meter shows no change, replace the switch
  3. Leaving the probe on the “COM” terminal, now locate the “NO” terminal (NO means Normally Open)and place the other probe on it. It should not be continuous. If it is, replace the switch
  4. Again, while keeping the probes from your meter in place, depress the button and look for the change, it should now read continuous.
    If not replace the switch

Repeat this test for the other two micro switches

If any switch fails the tests above, you have located your problem and can remedy it by simply replacing the defective switch(es). If they all pass the tests,
then the switches are all good and not the source of the problem you are experiencing.

And you can now move on to the next step in troubleshooting your Tuttnauer 2540M Autoclave

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