Black Box Techniques

Chapter X. Troubleshooting

 

 

Problem: When the Black Box is first turned on, there is no natural voltage reading.

 

a. The unit may not be turned on. Turn the knob clockwise until the unit is turned on. Be sure the mode switch is in the "up" natural voltage position.

 

b. The downrigger contact sleeve is not plugged in or is not making proper contact with the stainless steel cable.

 

c. The downrigger cable is not in the water.

 

d. The zincs on the boat are worn out or are not functioning resulting in a low reading which is below the minimum of .5 volts.

 

e. If you are in extremely pure freshwater, there may not be enough dissolved minerals present to create a normal voltage. Most bodies of freshwater will show readings very close to salt water but you may have found an exception.

 

 

Problem: Your natural voltage reading is too low (.1 to .5 volts)

 

a. Your boat zincs are worn out or may be covered with scum or white oxide powder. As a result, the zincs will not work properly. They should be cleaned or replaced.

 

b. The boat does not have enough zinc to protect the vessel. If you have cleaned the zincs and still get a low reading, more zincs may be needed.  Before adding zincs, be sure you do not have electrical leakage.

 

c. The boat is not properly bonded. Check the bonding connections and be sure all metal parts touching the water are bonded together with a wire connected to the battery ground. A kicker motor that is not bonded to the ground system of the boat will cause this problem.

 

d. There is electrical leakage in the hull.  A positive connection is leaking some electricity into the water.  This is quite common, particularly with battery switches, and bilge wire connections.  Find the source of the leak by testing for positive voltage on screws or metal parts in the vicinity of the switches or by disconnecting one circuit at a time (removing the fuse is a good way) and watching for a change in the natural electrolysis reading.  This problem is called a "hot boat".  This is a very common problem and the boat will have a very hard time catching fish.  You can test the whole boat at once by disconnecting the positive terminal from the battery.  If your reading on the downrigger cable changes, you have leakage somewhere.

 

Problem: Your natural voltage reading is near zero or negative.

 

a. You have the voltmeter connected backwards.

 

b. The downrigger cable or spool is grounded to the boat. Find the source of grounding and insulate the downrigger from the hull.

 

c. There is insufficient or pacified zinc on the boat. The zinc should be cleaned or new zinc should be installed. (Clean zincs with a stainless steel wire or bristle brush. Do not use a common mild steel wire brush).

 

d. There is electrical leakage in the hull.  A positive connection is leaking some electricity into the water.  This is quite common, particularly with battery switches, and bilge wire connections.  Find the source of the leak by testing for positive voltage on screws or metal parts in the vicinity of the switches or by disconnecting one circuit at a time (removing the fuse is a good way) and watching for a change in the natural electrolysis reading.  This problem is called a "hot boat".  This is a very common problem and the boat will have a very hard time catching fish.  You can test the whole boat at once by disconnecting the positive terminal from the battery.  If your reading on the downrigger cable changes, you have leakage somewhere.

 

e. The hull is not bonded. An aluminum boat that does not have the hull bonded to the engine can cause a negative downrigger cable reading. Run a bonding wire from the motor to the battery ground post and be sure the hull is also connected to the negative battery terminal. If you use two batteries in the boat, the ground terminals of both must be connected together and grounded to the boat hull.

 

 

Problem: Your natural voltage reading is too high (more than .800 volts)

 

a. Your downrigger spool and cable are not insulated from the boat's electrical system. Some downrigger manufacturers impose a strong positive charge on the downrigger wires as a means of controlling weight retrieval (short stop system).

 

b. Your downrigger cable has been changed to a metal with higher nobility than stainless steel. Monel wire will show higher readings than stainless.

 

c. The water where you are doing your testing is high in acid content. Heavy concentrations of certain algaes in freshwater can cause overly high natural readings on your Black Box. If you are testing in a heavy algae concentration, this may be the only problem. Before you assume something is wrong, test in clearer water.

 

 

Problem: When you test the voltage on your downrigger wire with a separate voltmeter, the voltage shows lower than the reading on the Black Box.

 

a. This is generally caused by the ground wire that comes from the Black Box to the negative side of the battery being overloaded. If there are several pieces of equipment like radios, fish finders and lights all hooked to a common ground wire, it can become overloaded and have a voltage drop. If the Black Box is hooked to this same wire, it will read a false ground level and send out an incorrect differential voltage.

 

b. Turn off all the auxiliary equipment on the boat and take new voltage readings. If this corrects the voltage error, the Black Box should be set up with a separate ground wire back to the battery.

 

c. Check the connections on the ground wire to be sure they are clean and making good contact. A corroded connection can cause the same problem as an overloaded wire.

 

d. The voltmeter in the Black Box is extremely accurate. This is rarely the problem.