Introduction & Chip Component Information................ 1-1 Circuit Board Access, Battery & Lamp Replacement............2-1 Alignment....................................3-1 Block Diagram & Interconnection Diagram.................4-1 Board Unit (Schematics, Layouts & Parts) MAIN Unit ............................................5A-1 LOCAL Unit ...........................................SB-1 DDS-1 Unit ............................................5C-1 DDS-2 Unit............................................5D-1 OSC Unit .............................................5E1 REG Unit.............................................5F-1 DISPLAY Unit..........................................5G-1 LPF Unit..............................................5H-1 PA Unit .............................................. 51-1 VR-A/-B/-C/-D Unit........................................5J-1 SW-A/-B/-C/-D Unit.......................................5K-1 MIC Unit .............................................5L-1 PHONE Unit...........................................5M-1 Exploded View & Miscellaneous Parts .................... 6-1 Accessory & Optional Board Units (Schematics, Layouts & Parts) TCXO-4 Master Reference Oscillator (option).........................7A-1 FM Unit-747 (option).......................................7B-1 YF-112A AM Crystal Filter (option)..............................7C-1 YF-112C CW Crystal Filter (option)..............................7D-1 FC-10 Automatic Antenna Tuner (option)...........................7E-1 MH-1B8 Hand-Held Microphone (accessory) ..........................7F-1 MD-1C8 Microphone (option)..................................7G-1 YH-77ST Lightweight Headphones (option)...................*......7H-1 This manual provides the technical information necessary for servicing the FT-840 hf transceiver. It does not include information on specifications, installation and operation, which are described in the FT-840 Operating Manual, provided with the transceiver, or on FT-840 accessories, which are described in the manuals provided with each. Servicing this equipment requires expertise in handling surface-mount chip components. Attempts by non-qualified persons to service this equipment may result in permanent damage not covered by warranty. For the major circuit boards, each side of the board is identified by the type of the majority of components installed on that side. In most cases one side has only chip components, and the other has either a mixture of both chip and leaded component (trimmers, coils, electrolytic capacitors, packaged ICs, etc.), or leaded components only.