Garmin GTN6XX Benutzerhandbuch

190-01007-A1

System Maintenance Manual GTN 6XX/7XX Part 23 AML STC

Rev. 7

Page 4-9

4.6.2 GTN TVS2 Assembly Check (GTN #1 Only)
The TVS assembly (refer to Section 6.9) and fuse on the power bus side of GTN #1 must be inspected. 
Verify operation of all four TVSs prior to replacing any failed TVS.

Check the TVS assembly (TVS2) as follows:

1. Ensure that the power to the bus is off and disconnect the connector in the TVS assembly.
2. Use a multi-meter to perform a diode check between the first connector contact (socket contact on

the first TVS) and ground. Refer to Figure 4-1.

3. The meter should indicate open with the red lead on the connector socket contact and the black

lead on ground:

a) The meter should indicate a diode drop of between 2.0V and 2.5V with the red lead on

ground and the black lead on the connector socket contact.

i.

If the diode drop is outside of the above range, replace the TVS diode corresponding
to the contact being checked.

ii. If the meter indicates a short, replace the TVS diode corresponding to the contact

being checked.

iii. If the meter indicates an open, check the wiring for faults. If the wiring is good,

replace the TVS diode corresponding to the contact being checked.

4. Repeat checks in the previous step for each of the three remaining contacts/TVS diodes.
5. On the other connector, verify continuity between each of the four contacts and the power bus.

a) If there is no continuity between the power bus and all four contacts, check the continuity of

the fuse.

b) If there is continuity between the power bus and some contacts but not others, check the wir-

ing to the ‘open’ contacts and repair as necessary.

6. Reconnect the connector in the TVS assembly.

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