VS-900

1. Make sure the patient is safe — swap in a backup unit if you need to.
2. Reproduce the complaint yourself and write down exactly what you see (screen, alarm, code).
3. Check power, battery, cables, accessories, and settings before ordering parts.
4. Then open the service manual above and follow its troubleshooting section.

Won't start source ↗

• Confirm AC is connected / battery has charge
• Check keypad-main, power board-power mgmt, and main-power mgmt cables
• Replace power board, power management board, then main board

Display blank/black or distorted source ↗

• Check display-to-main and backlight cables
• Replace main board or display

Touchscreen not responding source ↗

• Check if touchscreen is disabled: hold [Main Menu] quickkey >3 s
• Check touchscreen and control board cables
• Calibrate if touch position is off

No key/knob sound source ↗

• Check key volume isn't 0 ([Main]→[General Setup])
• Check speaker cable; replace speaker, then main board

Battery won't charge source ↗

• Replace battery
• Check battery interface board to power mgmt board cable
• Replace power management or battery interface board

'XX communication stopped' (NIBP/SpO2/Temp) source ↗

• Check cables between converter board and parameter module
• Replace parameter module or converter board

Won't power on source ↗

• Confirm AC cord/outlet and battery charge
• Check internal power/battery harnesses
• Measure power supply output against spec (15 V DC on Welch Allyn Connex and Philips VS3)
• Charge battery fully; replace if still empty

Touchscreen issues source ↗

• Check whether touch is disabled/locked
• Calibrate touchscreen
• Check touchscreen cables before replacing parts