Eagle 128 Installation And Operation Instructions Manual page 31

After installing the batteries, close the case and plug the sonar unit's
power cable into the socket on the battery case.
"D" cell battery
Install batteries in power case battery adapter. PPP-13 shown.
Turn the sonar unit on. If it doesn't work, make sure the battery
terminals are making good contact against the battery contacts. Also
check the wiring connections on the battery adapter. The red wire on
the power cable should be attached to the red wire on the battery
adapter and the power cable's black wire should be connected to the
black wire on the battery adapter.
If it still doesn't work, check the battery voltage. Most of the complaints
we receive about portable units result from stale batteries. Make sure
the ones you buy are fresh.
In cold weather the efficiency of dry cell batteries drops with the
temperature. We find it a good idea to have the sonar unit good and
warm along with the batteries before we leave home.
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