Chapter 8. Maintenance and Troubleshooting136 Model PM880 Portable Hygrometer User’s Manual8.4 Testing the Keypad1. If the menu is not active, press [MENU].2. Use the arrow keys to scroll to Service and press [ENTER].3. Use the arrow keys to scroll to Test and press [ENTER].4. Use the arrow keys to scroll to Test Keys and press [ENTER]. Thescreen appears similar to Figure 64.Figure 64: Test Keys Window5. Press any key on the keypad. The corresponding box on the screenshould darken.Note: If the box does not darken or if the key does not appear on the screen,contact the factory.6. Press [F3] and then [MENU] to return to taking measurements. If anykey does not appear on the screen, contact the factory.
