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Replacing the battery
The battery is mounted on the front of the Digital Unit PCB, located
immediately behind the front panel of the radio. To access the board take
the top and bottom covers off, remove the remaining two screws holding the front
panel on, then carefully unplug the two ribbon cables on the lower edge of the
digital unit PCB (see photo 2).
Photo 2: Bottom view of the front panel and
digital unit PCB (on edge). The two
ribbon cables with the blue stripes need to be
removed.
After unplugging the two ribbon cables carefully
turn the radio over and unplug the cables around the perimeter of the digital
unit PCB. The remaining ribbon cables along the bottom edge of the PCB
do not need to be removed! If you chose to remove all the cables you
may want to label the cables first. Be very careful with the ribbon
cables. Some older radios may have brittle ribbon cables, flex them with
caution.
The battery should be obvious, mounted on the
upper-left half of the Digital Unit PCB (see photo 3).
Photo 3: Front/upright view of the Digital Unit
PCB with the four cables unplugged around the
upper left, top, and upper-right portions of
the PCB. The white arrow points to the battery.
The front panel should be free enough to swing
forward to allow access to the Digital Unit PCB. It may help to block the
main chassis up an inch or so. There are two ribbon cables (each split in
two) connecting the radio to the RIT/NOTCH/NB controls - they can be unplugged
to allow the front panel to swing out even further if needed.
At this point you should be able to remove the gold
screws holding the Digital Unit PCB in place. Carefully remove the screws
and carefully swing the Digital Unit PCB away from the main chassis to allow
access to the solder points on the back side of the PCB (photo 4).
Photo 4: Rear solder points for BA1 on the back
side of the Digital Unit PCB
The location of the solder points for the battery
should be obvious from the rear of the PCB. I marked their location with a
red sharpie before I started working on the board. Carefully desolder the
rear solder points, using care near the SMT components seen in Photo 4. I
used a 15W iron and #1 desoldering braid (if you use this method be sure to work
just a little at a time to avoid overheating the board and surrounding
components).
The battery legs are soldered on both sides of the
board, so the front side may need to be desoldered. It is possible to
desolder the top (-) leg from the top/front of the board. Once the top leg
is free the battery can be bent away from the PCB to allow access to the lower
two (+) legs of the battery (photo 5). The battery should also have a
piece of foam tape holding it in position - remove the tape for better access.
The difficult part of the project is done once all three legs of the battery
have been desoldered.
Photo 5: BA1 bent over, revealing the two lower
legs.
Carefully tin all three legs of the new battery with
solder, then slip the new battery in position. Reuse the original foam
tape (if possible) to hold the new battery in position on the board.
Carefully solder the new battery from the back of the PCB, check each leg to
make sure the solder joints are solid on both sides of the PCB.
Photo 6: The new battery is installed and ready
to use
With the new battery installed (photo 6) all that
remains is to put everything back together and test the radio. My battery
was only off the PCB a short time - I didn't even lose any memories. The
new battery should be good for another 10 or so years.
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