Main Analog Input Test Page; Display Pattern Test Page - Garmin GNS 400W Series Maintenance Manual

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Test results are monitored via the main analog inputs test page (Figure 4-2).
Apply a 500 Hz, +5 volts to 0 volts square wave to unit pins J1-39 and 40. Measured value
should be 2.37 ± 0.25 V dc (66 to 81 ADC counts). Input measures peak voltage (not RMS).
Lighting Bus DC
Test results are monitored via the main analog inputs test page (Figure 4-2).
1. Supply 12.0 V dc to unit pin J1-39.
2. Ensure the power supply ground is connected to the unit ground J1-77 and 78. Measured
value should be 12.0 ± 5% V dc.
Memory Battery Voltage
At the end of battery life the unit typically alarms at 2.46 volts and clears the alarm at 2.63 volts.
Verify 190 to 145 ADC counts (3.8 > V > 2.9 volts) via the main analog inputs test page (Figure
4-2).
Figure 4-2. Main Analog Input Test Page (Test Mode)
Display Pattern Test
Starting from the display pattern test page (Figure 4-3), use the 'RNG' buttons to cycle through
all of the display patterns to verify all pixels are driven and color contrast is acceptable.
Figure 4-3. Display Pattern Test Page (Test Mode)
GNS 400W Series Maintenance Manual
190-00356-05
Page 4-11
Rev. A