GE LBI-38378C manual RF Board Access, Control Board Access

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LBI-38378

RF Board Access

Holes are located in the RF Board shield for alignment of the Reference Oscillator (U3), Modulation Balance pot (R18), VCO Modulation pot (R19), 2nd Local Oscillator Adjustment (T1), and the Quadrature Detector Adjustment (T2). To align these items, shield removal is not necessary.

If removal of the RF Board from the case is necessary, first remove the UDC antenna jack and the top RF antenna jack with appropriate spanner wrenches. Next, remove the five (5) Torx screws (B) that secure the shield then lift and remove the shield. Remove the two (2) remaining Torx screws (C) near the Power Amplifier Module. The RF Board and eggcrate casting can now be lifted from the Rear Cover to gain access to the chip component side of the board. If necessary, the RF Board can be separated from the eggcrate casting. Remove the two (2) Torx screws that secure the Power Amplifier Module and remove the four (4) screws on

Figure 7 - RF Board Access

the chip component side of the board that secure it to the casting.

Reassemble the unit in reverse order. Observe screw lengths.

Control Board Access

To gain partial access to the Control Board, remove the five (5) screws (D) securing the shield and board. An earlier Front Cover Assembly has an additional screw located just below connectors J4/P4 (DD). See Figure 8. Remove the shield.

Many of the test points on the Control Board are acces- sible at this point; however, the Front Cover Assembly should not be powered-up without first reinstalling the screw into the lower right-hand hole to ground the board. Also, the three (3) screws securing the top flex connectors need to be reinstalled for good flex connections. USE CAU-

Figure 8 - Control Board Access

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Contents Maintenance Manual Table of Contents Transmitter SpecificationsGeneral ReceiverRadios, Antennas, Batteries Features IntroductionDescription System Model Front Cover Assembly Rear Cover AssemblyBattery Packs AntennasUniversal Device Connector ProgrammingUDC PIN Functions Name Input or USE Output Operating Tips AccessoriesOperator Manual Intrinsically Safe UsageMaintenance Preventive MaintenanceFront and Rear Cover Separation Disassembly / ReassemblyTools Required RF Board Access Control Board AccessEarlier Front Cover Assembly Keypad Flex Removal Speaker, Microphone and Flex Circuit AccessUDC Flex/UDC/Monitor Button/PTT Switch Assembly Removal Block Diagram Front Cover Assembly Earlier And Control Board Block Diagram LCD Board Access Later Front Cover Assembly Keypad Flex Removal