Service Manual
iFLEX5
© Hirschmann Rev. I 0522/17
190154_I.DOC
16
11 A2B PROBLEM
A2B problem
Ensure the
bypass
plug is
installed.
Turn power off, remove bypass plug, and
measure the resistance at the boom nose box
between terminals 1 and 3 with an ohmmeter.
Switch closed = 0 ohms (weight installed)
Switch open = 1 Megaohm (weight removed)
Are the control levers
locked out and is the
crane in an anti-two
block condition?
Lower the hook block and/or
headache ball to correct the
two-block problem. If two
hoists are in use, both hooks
must be lowered.
If wiring is
correct, replace
A2B switch.
NO
Is the anti-two
block warning
light on?
NO
YES
Remove wires and measure the A2B
signal in the cable reel between terminal
7 and 8 with an ohmmeter.
Switch closed = 4700 +/- 500 Ohms
Switch open = > 1 Megaohm.
YES
Are the ohmmeter
readings correct?
YES
Plug the bypass
plug into the
boom nose box
and refer to
system wiring to
check wire
connections in
boom nose box.
NO
Check for
damaged length
cable and wiring.
If broken length
cable, refer to
system wiring.
Are the
ohmmeter
readings correct?
Are the
ohmmeter
readings correct?
NO
Replace the
slip ring.
YES
A problem lies with either the wiring
harness, cable reel length/angle
boards, and/or the central unit.
Ensure bypass plug is plugged into the
boom nose box. Remove wires and
measure the A2B signal in the cable reel
between the X1: (brown) an X2 (red) wires
on the slip ring with an ohmmeter.
Switch closed = 4700 +/- 500 Ohms
Switch open = > 1 Megaohm.