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Altimeter — Manual
4
Maintenance & Repair
No special maintenance is required.
The instrument has no serviceable parts inside. In the case of malfunction,
it must be sent to factory for a repair. A backup battery replacement is an
exception. See section 7.6.1 for more details.
Altimeters equipped with a backup battery shall undergo battery capacity
check annually. The procedure is described in section 7.3.
5
Troubleshooting
5.1
Freeze During Engine Start
In certain aircraft installations instrument freezes and then reboots itself,
when some large current consumers are switched on. This is caused by a very
short voltage drop as a consequence of the consumer's power demand.
A simple electronic circuit illustrated in Figure 6 may help in this case. The
circuit consist of two elements.
• The diode prevents reverse flow from the capacitor. We recommend
Schottky Diode 1N5818G. You can also use some other diode, which has
a low voltage drop, 1 A forward current and at least 20 V of blocking
voltage.
• The capacitor serves for a very short energy reserve. Use an aluminium
electrolytic capacitor with about 1000 F, at least 25 V and at least
100 C working temperature.
+12 V
GND
Figure 6: Circuit that may prevent sudden voltage drops in certain installa-
tions.
Diode
1N5818G
Capacitor
1000 μF, 25V, 108°C
17
4. Maintenance & Repair
Instrument
© Kanardia 2015-2020
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