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Mercathode help testing?

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14K views 11 replies 6 participants last post by  tbirdvet  
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#1 ·
Can anyone make sense of this..
Mercathode System Testing
If your boat is equipped with a Mercathode system, there is a simple way to test if the system is operating properly. The goal is to check the output from the Mercathode controller. When the boat is in the water, disconnect the orange wire that comes from the anode at the mercathode controller. Set the digital reader to show milliamps. Connect the black meter lead to the terminal on the controller. Connect the red meter lead to the end of orange wire. If using the blue or black Mercathode controller, the reading should be 25 or less milliamps, to as much as 200 milliamps in saltwater areas. If using the red Mercathode controller, the readings should be less than 25 milliamps in fresh water areas to as high as 400 milliamps in saltwater areas.

So when it says connect the black tester probe to the terminal does this mean to the negative terminal? and just touch the red tester probe to the orange wire you removed to see a reading?
Also it says you have to do this in water,is there a way I can test while its just sitting on the trailer?
 
#2 ·
You are measuring miliamps, the red end goes to the orange wire, and the black probe goes to the terminal for the ORANGE wire. To get an amps reading you have to put the meter in line with the circuit being checked.

Yes, it has to be in the water. However, if the boat is not in the water you should also check the condition of the cathode wire on the outside of the boat. This is located on the bottom of a box mounted at the bottom of the transom ring. If you lay on your back under the drive (in trailer position) and look up at the bottom of the transom ring, you will see a bare wire running across the bottom. That needs to be clean (no paint) and not broken. If it is dirty clean it with solvent and q-tips. Sometimes these get bottom painted and then they don't work so good.

Henry
 
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#4 ·
What wire? The little paper clip looking one on the plastic block under the outdrive? If so, you need to replace the entire reference electrode (the black box under the outdrive.) I'm going to do mine this week.
 
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