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-
qualied 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 specication.
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 specication, 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
Specications
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
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