BTC Troubleshooting & Repair 2 — Questions and Answers
Question 1: A patient monitor displays a 'low battery' alarm even when plugged into AC power. What is the most likely cause?
- Faulty AC/DC power supply board
- Depleted battery that cannot hold charge (Correct answer)
- Software firmware corruption
- Loose power cord connection
Correct answer: Depleted battery that cannot hold charge
A battery that can no longer hold a charge will trigger low-battery alarms even on AC power because it fails to charge above the alarm threshold.
Question 2: During a defibrillator self-test, the device fails to deliver the set energy level. Which component should be inspected first?
- Patient cable leads
- Capacitor and charging circuit (Correct answer)
- Display screen
- Battery contacts
Correct answer: Capacitor and charging circuit
The capacitor and charging circuit are responsible for storing and delivering the programmed energy; failure here directly causes under-delivery.
Question 3: An infusion pump produces a 'downstream occlusion' alarm but the IV line appears clear. What should the technician check next?
- Pump motor speed
- Pressure sensor calibration (Correct answer)
- Flow rate setting
- Battery charge level
Correct answer: Pressure sensor calibration
A miscalibrated pressure sensor can falsely detect occlusion even when the line is patent.
Question 4: An electrosurgical unit (ESU) produces no output when activated. After confirming the power supply is good, what is the next logical step?
- Replace the footswitch cable
- Test the RF output stage and power transistors (Correct answer)
- Recalibrate the front-panel display
- Check the patient return electrode pad
Correct answer: Test the RF output stage and power transistors
The RF output stage and power transistors generate the high-frequency energy; a fault here results in no output despite normal power supply.
Question 5: A ventilator's tidal volume reading is consistently 20% lower than the set value. What is the most probable cause?
- Flow sensor fouling or miscalibration (Correct answer)
- Incorrect alarm limit settings
- Patient circuit condensation only
- Low oxygen supply pressure
Correct answer: Flow sensor fouling or miscalibration
A contaminated or miscalibrated flow sensor will underreport delivered volume, creating a consistent discrepancy.
Question 6: Which tool is most appropriate for verifying electrical isolation between a medical device chassis and ground?
- Digital multimeter set to DC voltage
- Megohmmeter (insulation resistance tester) (Correct answer)
- Oscilloscope
- Clamp-on ammeter
Correct answer: Megohmmeter (insulation resistance tester)
A megohmmeter applies high voltage to measure insulation resistance between chassis and ground, confirming electrical isolation.
Question 7: A pulse oximeter reads SpO2 at 100% on all patients regardless of their condition. What is the most likely fault?
- LED emitter failure — no light emitted
- Photodetector saturation or short circuit (Correct answer)
- Incorrect patient mode selected
- Probe cable open circuit
Correct answer: Photodetector saturation or short circuit
A shorted or saturated photodetector sends a maximum signal to the processor, causing it to always report 100% saturation.
BTC Troubleshooting & Repair 2
A patient monitor displays a 'low battery' alarm even when plugged into AC power.
What is the most likely cause?