Corrosion On Underwater Parts, With Mercathode Or Impressed Current Protection - Mercury BRAVO Service Manual

TROUBLESHOOTING
Corrosion On Underwater Parts, With MerCathode Or Impressed Current
Protection
DRIVE CORRODING
Poor connection between reference
electrode (BRN) lead or anode
(ORN) lead and MerCathode
controller.
Faulty MerCathode reference
electrode.
Faulty MerCathode controller.
Too much cathode (such as stainless
steel).
Loss of continuity between sterndrive
components and ground.
Sacrificial anodes consumed, painted
or inoperative.
MerCathode reference electrode or
anode painted.
Page 1C-30
Cause
SERVICE MANUAL NUMBER 28
Special Instructions
Clean and/or tighten connection.
Repair wiring.
Disconnect reference electrode lead
(BRN) from the controller "R"
terminal. Connect the lead to positive
(+) terminal of a digital multi-meter (set
on 0-2000 millivolt scale). Connect
negative (–) meter lead to negative (–)
battery terminal. Note meter reading;
then repeat the test with a test
silver/silver chloride reference
electrode held behind the drive. The
same reading should be obtained in
both cases. If not, replace the
reference electrode.
With anode and reference electrode
leads connected to controller, connect
a jumper wire between "R" and
negative(–) terminals on controller.
Connect positive (+) lead of volt meter (set
on 0-20 scale) to "A" terminal on controller.
Connect the negative (–) meter lead to the
negative (–) controller terminal. Reading
should be as follows:
D Freshwater Areas = 11.5 volts
minimum
D Seawater Areas = 3.55 volts
minimum
If the reading is low, replace the
controller.
MerCathode system overpowered by
large quantity of stainless steel below
the waterline.
Ensure continuity (check continuity
wires and washers).
Replace anodes.
Remove paint or replace anode or
MerCathode reference electrode.
90-863160 MAY 2000