AR 10009284, Operating And Service Manual

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Model 40T26G40A
26 Rev A
Disconnect power, RF, and any other interface connectors. On the rear of the unit, remove any screws
used to connect brackets to the amplifier. On the front of the unit, remove the four screws holding the
front panel onto the cabinet. Carefully slide the amplifier out of the front of the cabinet.
2. Remove the 12 screws that secure the lower cover and the 12 screws that secure the upper cover. Remove
the covers to gain access to the interior of the TWTA.
Vacuum dust and debris from inside the enclosure. Clean dust from the TWTA and its flying leads.
Remove any dirt from around the three high-voltage connectors. While the cover is removed, check for
loose wires, components, or fasteners.
Reassemble in the reverse order.
4.4 TROUBLESHOOTING
Table 4-1. Model 40T26G40A TWTA Troubleshooting Guide
Symptom Possible cause
TWT or power supply overtemperature Air inlet filter dirty
Collector heat sink dirty
Inadequate clearance behind TWTA
High air inlet temperature
Defective blower or power supply
No response when main power turned on
Panel open interlock switch open
Control module display does not come up; unit does not beep when
powered up
Shorted or defective control module power supply
Control module failure
Control module does not boot EPROM(s) missing, EPROM pins are bent, 64-conductor ribbon
cable is defective.
Control module datalink failure error or Communication Problem
error appears
HPA interface failure.
Fiberoptic link failure
+15 VDC supply failure
Heater power supply does not come up Defective low voltage power supply module
Defective heater power supply module
No high voltage Open external interlock
Keylock switch on
INHIBIT or REMOTE
Defective high voltage power supply.
Voltages normal, but no RF output, helix current low No RF input
Defective remote control board
Defective SSA
Gain turned down
After reviewing the symptoms of the failure
, the user may want to check for a loose connector or component
especially after rough handling of the unit . Look externally for physical damage and internally for unmated
or loose parts .
The service technician should become familiar with the internal mechanical construction to permit correct re-
assembly
. Limited troubleshooting may be conducted, with caution, based on the failure symptom and an
understanding of the logic/schematic diagrams .