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W450769A 01/14
3.8.1 Checking the Reeling Drum Cable
The outer braid of the cable carries the Anti-Two-Block feed to the switches. If the cable sheath is
damaged, this may cause a short circuit to the boom/chassis and indicate a fault code above “B 8”(See
SECTION 3.3.2 GROUP “B” FAULT CODES
). The same fault code will be indicated if the ATB switch
is closed and the inner core of the cable is shorted to the chassis at some point in the wiring.
1. Carefully inspect the Reeling Drum cable for wear.
2. Check for signs of damage to the outer sheath of the cable.
3. Check for any signs of severe “kinking” or crushing of the cable.
3.8.2 Checking the Anti-Two-Block Circuit
Before continuing, ensure the connectors are correctly connected to the ATB switches at the boom
head/jib.
1. Remove the Reeling Drum cover.
2. Disconnect the slip-ring arm from the plug by pulling it away from the center of the Reeling
Drum.
3. Close the ATB switch at the boom head by suspending the weight from it or pulling on the chain.
4. Measure the resistance between TB2-1 & TB2-2 terminal connections on the sensor arm.
5. With the ATB switch closed, the resistance should be less than 300 ohms. If not, inspect the
Reeling Drum cable, ATB switch, and the boom head connectors for an Open circuit.
6. Open the ATB switch at the boom head by lifting the weight.
7. Measure the resistance between TB2-1 & TB2-2 terminal connections on the sensor arm.
8. With the ATB switch open, the resistance should be greater than 10,000 ohms. If not, inspect
the Reeling Drum cable, ATB switch, and the boom head connectors for a short circuit.
FIGURE 3.8.2 - CHECKING THE ANTI-TWO-BLOCK CIRCUIT
