HF/VHF/UHF ALL MODE TRANSCEIVER
FT-991
Introduction
This manual provides the technical information necessary
for servicing the FT-991A HF/VHF/UHF ALL MODE
TRANSCEIVER.
Servicing this equipment requires expertise in hand-
ing surface-mount chip components. Attempts by non-
qualified persons to service this equipment may result
in permanent damage not covered by the warranty, and
may be illegal in some countries.
Two PCB layout diagrams provided for each double-
sided board in this transceiver. Each side of the board
is referred to by the type of the majority of components
installed on that side ("Side A" or "Side B"). In most
cases one side has only chip components, and the other
has either a mixture of both chip and leaded components
(trimmers, coils, electrolytic capacitors, ICs, etc.), or
leaded components only.
While we believe the information in this manual to be
correct, YAESU assumes no liability for damage that
may occur as a result of typographical or other errors
that may be present. Your cooperation in pointing out
any inconsistencies in the technical information would
be appreciated.
Important Note
This transceiver was assembled using Pb (lead) free solder, based on the RoHS specification.
Only lead-free solder (Alloy Composition: Sn-3.0Ag-0.5Cu) should be used for repairs performed on this apparatus. The solder stated
above utilizes the alloy composition required for compliance with the lead-free specification, and any solder with the above alloy com
-
position may be used.
Caution
Risk of explosion if battery is replaced by an incorrect type. Dispose of used batteries according to the instructions.
Technical Supplement
EH067M90B
©2017 YAESU MUSEN CO., LTD.
Contents
Exploded View & Miscellaneous Parts
Block Diagram
Connection Diagram
Alignment
Board Unit (Schematics, Layouts & Parts)
MAIN Unit
PLL Unit
EDSP Unit
CNTL Unit
HF-PA Unit
V_U-PA Unit
PANEL Unit
TUNER Unit
JACK Unit
SCP Unit
DSP Unit
Summary of Contents for FT-991A
Page 10: ...BLOCK DIAGRAM 1 FT 991 Technical Supplement Block Diagram...
Page 11: ...CONNECTION DIAGRAM 1 FT 991 Technical Supplement Connection Diagram...
Page 36: ...FT 991 Technical Supplement MAIN 1 Circuit Diagram MAIN Unit...
Page 37: ...FT 991 Technical Supplement MAIN 2 Parts Layout side A MAIN Unit 1 2 3 4 5 A B C D E F G...
Page 38: ...FT 991 Technical Supplement MAIN 3 Parts Layout side B MAIN Unit 1 2 3 4 5 a b c d e f g...
Page 68: ...FT 991 Technical Supplement PLL 1 PLL Unit Circuit Diagram...
Page 69: ...FT 991 Technical Supplement PLL 2 PLL Unit Parts Layout side A side B 1 2 3 A B C...
Page 73: ...FT 991 Technical Supplement EDSP 1 Circuit Diagram EDSP Unit...
Page 79: ...FT 991 Technical Supplement CNTL 1 CNTL Unit Circuit Diagram...
Page 80: ...FT 991 Technical Supplement CNTL 2 CNTL Unit Parts Layout side A A B C D E F G 1 2 3 4...
Page 81: ...FT 991 Technical Supplement CNTL 3 CNTL Unit Parts Layout side B a b c d e f g 1 2 3 4...
Page 87: ...FT 991 Technical Supplement HF PA 1 HF PA Unit Circuit Diagram...
Page 88: ...FT 991 Technical Supplement HF PA 2 HF PA Unit Parts Layout side A 1 2 3 4 A B D F G E C 5...
Page 89: ...FT 991 Technical Supplement HF PA 3 HF PA Unit Parts Layout side B 1 2 3 4 a b d f g e c 5...
Page 96: ...FT 991 Technical Supplement V_U PA 1 Circuit Diagram V_U PA Unit...
Page 97: ...FT 991 Technical Supplement V_U PA 2 V_U PA Unit Parts Layout side A 1 2 3 A B C D E F G H...
Page 98: ...FT 991 Technical Supplement V_U PA 3 V_U PA Unit Parts Layout side B 1 2 3 a b c f h j d e g i...
Page 105: ...FT 991 Technical Supplement PANEL 1 Circuit Diagram PANEL Unit...
Page 113: ...FT 991 Technical Supplement TUNER 1 TUNER Unit Circuit Diagram...
Page 114: ...FT 991 Technical Supplement TUNER 2 TUNER Unit Parts Layout side A 1 2 3 4 A B C D E F G H...
Page 115: ...FT 991 Technical Supplement TUNER 3 TUNER Unit Parts Layout side B...
Page 119: ...JACK 1 JACK Unit Circuit Diagram FT 991 Technical Supplement...
Page 120: ...JACK 2 JACK Unit Parts Layout side A side B FT 991 Technical Supplement...
Page 122: ...FT 991 Technical Supplement SCP 1 Circuit Diagram SCP Unit...
Page 123: ...FT 991 Technical Supplement SCP 2 Parts Layout SCP Unit side A side B...
Page 127: ...FT 991 Technical Supplement DSP 1 DSP Unit Circuit Diagram...
Page 128: ...FT 991 Technical Supplement DSP 2 DSP Unit Parts Layout side A side B...
