Yaesu FT-840, Service Manual

Page: 8 / 152

Lithium Back-up Battery Replacement, Backup Switch
&
Case Cover Screws
Lithium Back-up Battery Replacement
D
With the top and bottom covers removed,
locate the Lithium Battery on the Local
Unit (photo??? ).
D
Using your finger, slide the battery inward,
then slightly pry up the outer edge of the
battery, so that it ejects freely upward and
outward through the slots at the top and
bottom of the holder.
D
Carefully note the polarity
( +
side facing
up) and battery type information.
D
Install the replacement battery in the re­
verse manner.
Backup Switch
Located next to the Lithium Battery is the
memory back-up switch
S2002
labeled
"BACK-UP".
It is normally kept in the ON
position to ensure that memorized informa­
tion is maintained (by a small amount of
power from the lithium battery) when the ra­
dio is off, or the DC power source is removed.
If
you do not plan to operate your radio for
extended periods of time, turn the switch to
the
OFF
position to conserve battery life. Move
the selector using the tip of a ball-point pen or
similar object. To prolong battery life, ensure
that the radio is turned on when switching the
back-up switch from
OFF to ON. This reduces
the current demand placed on the battery by
the radio's circuits from an un-powered state.
Case Cover Screws
Please note that there are
three
different
types of screws used for top & bottom cover
attachment, and front panel assembly.
Refer to the figure at the right for proper
screw identification and below for location.
Tup
Cover: 4
x
Oval-Head,
1
x
Binding Head
Bottom Cover:
5 x
Binding Head
Front Panel: 4
x
Flat Head
Removing Back-up Battery
Slide battery inward, then pry up to eject
Inserting Back-up Battery
Slide battery inward, then pry up to eject
Battery BACK-UP switch
BACK UP
ON OFF
II
Case Cover Screws
T
'
i
Binding-Head Screw
M3 x 6B
Flat-Head Screw
M3 x 6B
Oval-Head Screw
M3 x 6B
2-2
FT-840 Technical Supplement