Garmin GPS 155 Repair Manual

Also see for GPS 155: Pilot's guide addendum

Garmin GPS 155 Repair Manual Manual pdf 14 page image

TROUBLESHOOTING CHART (cont.)Unit does not detect external Check external power connectionpower4 Replace Main Board (see Section 3.2.4)No serial data output Replace Main Board (see Section 3.2.4)No external CDI output or external Check connections and verify operation in TestCDI functions improperly Mode (see Section 4.3.2)Replace Main Board (see Section 3.2.4)Invalid characters displayed Replace ROM (see Section 4.2)Replace Main Board (see Section 3.2.4)1If UTC Time is incorrect, unit may be reset by holding the CLR key down while turning the unit on. The unit must then beattached to an antenna, allowed to search the sky and collect new almanac data. This process may take 20-30 minutes. CAU-TION: All user waypoints/settings will be lost if the unit is reset.2The GPS 155 will eventually perform an AutoLocate™ and lock onto satellites, however this can add an additional 10-15 min-utes to the normal lock-on time.3Display of low velocity numbers when not moving can occur when the unit is in 2D mode and should not be considered aproblem. However, this should seldom occur in 3D mode.4The “Turning Off” message appears at/below approximately 9 VDC external power.SECTION 3DISASSEMBLY INSTRUCTIONSTo avoid damaging the GPS 155’s circuit boards and assemblies, the following procedures should becarefully followed. Assembly drawings are included in Section 5 for reference (Figures 12 through 15).NOTE: The NavData card should be removed before disassembling the unit.3.1 REMOVAL OF THE COVERS1. Remove the two M3 x 5mm screws (211-50227-05) retaining the top cover (115-00037-00).2. Remove the top cover by sliding it rearward approximately 1/4” until the retaining lip is fully exposed. The covercan then be lifted off the unit.3. Carefully turn the unit over. CAUTION: The GPS 155 contains numerous static-sensitive components. Alwaysobserve proper anti-static precautions.4. Remove the two M3 x 5mm screws (211-50227-05) retaining the bottom cover (115-00038-00).5. Remove the bottom cover by sliding it rearward about 1/4” until the retaining lip is fully exposed. The cover canthen be lifted off the unit.NOTE: If further disassembly is required, it is a good idea (at this time) to disengage the batterypack wire from the main board (see figure 12).11