Common faults and maintenance methods of PB840 ventilator

Common faults of ventilator and solutions
Common faults of ventilator and solutions
11月 2, 2022
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hamilton ventilator parts

1. The oxygen concentration is too low

Fault phenomenon:

Ventilator alarm: The oxygen concentration is too low, the others are normal.

Fault analysis:

The general reasons for the alarm of the oxygen concentration of the PB840 ventilator is too low are: insufficient oxygen supply pressure on the wall; inaccurate oxygen concentration detection caused by the failure of the oxygen battery; and the oxygen flow sensor fails.After analyzing the cause, troubleshooting and overhaul will be carried out.


  • Calibrate the oxygen flow sensor and the result passes, but an error message appears;
  • Check the oxygen pressure of the oxygen supply to the patient area in the center, the pressure gauge shows that the oxygen pressure is normal, and the oxygen pressure failure is ruled out.;
  • Measure the oxygen sensor cable, the wiring is normal and the appearance is normal, then consider whether there is a problem with the oxygen battery.
  • After troubleshooting the above reasons, it was determined that it was the failure of the oxygen battery.

After replacing the oxygen battery, turn on the power, perform an EST self-test, pass the test, and use it again. Check that the set value of the oxygen concentration is consistent with the monitored air supply oxygen concentration, and the linear change is good, everything is normal, and the fault is relieved.

2. Unable to connect to the settings

Fault phenomenon:

After the ventilator is turned on, it shows that the settings cannot be connected, the ventilator is wrong, and there is a sound and light alarm.

Fault analysis:

After rebooting, the alarm is still on. Since the breathing valve test is an extended self-test, the extended self-test is performed. The result fails, indicating that there are two errors. Check the maintenance manual. The error is that the flow sensor is faulty.


First disassemble the equipment to check the other components of the breathing module, and find that there are many debris on the gasket of the exhalation valve. It is judged that these debris destroy the sealing of the exhalation valve, causing the flow monitoring to deviate from the actual value.

Clean with medical disinfectant alcohol, test again after installation, the result is passed, and the fault is relieved.

3. Severe blocking alarm

Fault phenomenon:

The PB840 ventilator has a serious obstruction alarm during operation.

Fault analysis:

The PB840 ventilator has a blocking alarm during operation, which is usually caused by two conditions. It may be that the pipeline is stagnant or folded, or it may be that the filter is clogged at the inhalation or exhalation end.

In this case, there will be two displays of the alarm: Severe ocelusion and Screen blocked.

  • If the ventilator shows Severe ocelusion, it indicates that there is a blockage in the ventilator pipeline, which can be solved by cleaning up foreign objects in the pipeline or replacing the pipeline.
  • If the ventilator displays Screen blocked, it will indicate that the touch screen sensor of the ventilator has failed.

4. Touch screen sensing failure

It is divided into three situations: partial failure, unresponsiveness, and complete non-response.

  • Local failure is generally caused by damage to infrared transmission or reception;
  • The unresponsiveness is generally due to the accumulation of too much dust on the outer frame of the screen, which blocks infrared transmission and reception. It may also be that there is a lot of dust inside;
  • Complete non-response is due to poor fixation of the internal touch frame board, deviation, damage to the touch frame board or damage to the display motherboard.

5. Low moisture volume

 Fault phenomenon:

The tidal volume in the patient’s parameter setting is 500ml, and the actual tidal volume is low.

Fault analysis:

If the ventilator prompts that the patient’s tidal volume is severely low, and the tidal volume of the ventilator is set to 450mL, it shows that the exhaled tidal volume is about 340mL.If the patient is in normal condition, there are three main reasons for this problem: first, the patient’s circuit leaks; second, the active exhalation valve is dirty; and third, the flow sensor fails.


If there is no error message in the system diagnostic log, run SST to check whether the breathing circuit is normal.

If the flow sensor fails to pass the inspection, it can be temporarily ignored and the inspection can continue until the problem of air leakage in the breathing circuit is eliminated.After troubleshooting the air leakage problem, run EST to observe whether the air leakage test can pass the test. If there is a test error, check and clean the exhalation valve.When cleaning, the sealing ring should be removed and cleaned with ethanol to solve the fault.

Run EST again for retest. If the system still prompts that the flow sensor test fails, you need to observe the flow sensor data.

If during the test, when the oxygen flow sensor is 120L/min, the exhaled flow sensor is 100L/min, and when the air flow sensor is 120L/min, the exhaled flow sensor is still 100L/min, it can be determined that the exhaled flow sensor is faulty, as long as the faulty flow sensor can be replaced.

6. Unable to enter the working state

Fault phenomenon:

When the ventilator is turned on, warning messages such as “hardware alarm” and “System error” appear on the screen, accompanied by an alarm tone, and the ventilator cannot enter the working state.The upper screen shows that all tests have never been run or failed, the GUI fault indicator and SVO indicator are always on, and the height alarm light and BDU fault indicator are flashing.There is no device serial number displayed in the ventilator configuration menu, and the diagnostic code is ZB0086.

Fault analysis:

It is initially suspected that the cause of the failure is that the GUI and BDU communication have not been contacted.

The point of failure that caused the failure may be components such as the power module, AI board, GUI CPU board, BDU CPU board, or GUI TO BDU cable.

Check the repair manual, the fault code ZB0086 indicates that the BD communication is interrupted, disassemble the left panel of the BDU, check the alarm indicators of the BDU CPU and AI board, and find that the first red light of the BDU CPU indicator flashes, the 8 red lights below are always on, and the 2 yellow indicators under the TEST button are always on.


Since there is no failure of the AI board, BDU CPU board, GUI components, and power module, consider the failure of the motherboard. After replacing the motherboard with the above method, the boot is normal, and the relevant calibration, EST, and SST tests are run. All pass, restart the ventilator, and work normally.

7. Power failure

Fault phenomenon:

The power supply fails and the compressor does not work at all. The alarm prompts: LOSS AC POWER, NO Cormpressed Air.

Fault analysis:

The connection between the compressor and the host is normal. All power cords, communication interfaces, and air circuit connectors are reconnected again. The AC indicator light next to the host switch is not on when the power is connected. The same is true for another power connector. The simulated lung ventilation is normal. Turn off and observe the machine. It is found that the AC indicator light is not on, and the host overcurrent protection switch jumps on.


It is judged that the power module is broken. In addition, take the power module of a good 840 ventilator, press the host button, connect to the AC, the AC indicator light next to the machine switch is on, turn on, the compressor is working normally, and there is no abnormality when connected to the simulated lungs. Restart the operation EST PASSED SST PASSED The machine can work normally.

Disassemble the faulty power module and find that one of the fuses powering the air compressor has been burned. After replacing the fuse, measure the output voltage, normal, restore to the original machine, turn on, do EST, SST are PASSED, so troubleshooting, the machine returns to normal use.