Midmark M9® -05x / M11® -05x Sterilizer Water Level Sensor Test and Repair

WARNING

To prevent risk of shock always disconnect power before removing covers or performing any service procedure.

 

Model

 M9 -050, -053 M11 -050, -051, -053
Serial Number All All
WARNING

Some procedures require power to be connected with covers removed. Line voltage is present. Use extreme caution to prevent electric shock.

M9/M11 Steam Sterilizer Water Level Sensor Testing

1.Set meter to VDC.

2.Place meter probes on points TP177 and TP292 (as shown in the figure above).

3.Activate the water level sensor by filling chamber with water up to the sensor and check reading.
LED D52 should light up.

Meter Reading

Required Action

No water touching sensor = approximately 3.3 VDC

Water touching sensor = approximately 0 VDC

PC board is OK.

Sensor is OK.

System functioning as expected, no further action required.

No water touching sensor = approximately 3.3VDC

Water touching sensor = approximately 3.3VDC

Perform Ground Connection Test.

Any other reading

Replace PC board.
WARNING

Some procedures require power to be connected with covers removed. Line voltage is present. Use extreme caution to prevent electric shock.

M9/M11 Steam Sterilizer Water Level Sensor Testing

1.Disconnect power from product.

2.Set meter to measure resistance.

3.Place one meter probe on TP292 and one meter probe on the chassis ground connection on the base (as shown in figure above).

Meter Reading

Required Action

Resistance measures less than 10 ohms.

PC board is OK. Perform Continuity Test.

Resistance measures greater than 10 ohms.

PC Board is damaged

Proceed to Pinched /Cut Wires test

Do not replace PC Board until after performing Pinched /Cut Wires test.
WARNING

Some procedures require power to be connected with covers removed. Line voltage is present. Use extreme caution to prevent electric shock.

M9/M11 Steam Sterilizer Water Level Sensor Testing

1.Apply power to product.

2.Set meter to measure VDC.

3.Place red meter probe on the chassis ground connection on the base and black meter probe on TP292 on the PC board (as shown in figure above).

Meter Reading

Required Action

Voltage reading is approximately 12VDC.

Checked for pinched or cut wires in the following locations:

-Door motor wires.

-Door motor supply wire harness.

-12VDC power supply wire harness.

-Fan wires.

If a pinched or cut wire is found to be contacting the metal surface of the product, replace the affected component.

After fixing pinched/cut wire, replace PC Board.

Voltage reading is approximately 0VDC.

No pinched/cut wires identified.

Replace PC Board.
WARNING

Sterilizer or components may be hot or become hot. Wait until the sterilizer or components are cool to the touch before continuing service.

M9/M11 Steam Sterilizer Water Level Sensor Testing

Ensure that the sensor is dry. Any water on the sensor could cause inaccurate readings.

Resistance Test

1.Empty any water from chamber and dry sensor.

2.Disconnect wire from sensor terminal.

3.Set meter to Ohms (Ω).

4.Place one meter probe on sensor terminal and the other probe on the chamber wall (as shown in the figure above).

Equipment Alert

Residue buildup on the sensor disk can cause malfunctions during the Filling mode. Clean the sensor disk with Speed-Clean and an abrasive pad; then dry disk thoroughly.

Meter Reading

Required Action

OL

Water level sensor is good.

Any reading other than OL

Replace water level sensor.