6. LENGTH READING PROBLEM - continued
Measure length signal of amplified output on main board in central unit . Measure between test
point MP15 (analog ground) and test point MP6 (length signal). The measurement should be
between +0.5 volts and +4.5 volts. +0.5 volts with the boom fully retracted and the length
potentiometer set fully counterclockwise to a soft stop (minimum sensor output). +2.1 volts (±0.1 V)
with boom fully extended (actual working range). +4.5 volts with the potentiometer turned
completely clockwise 10 turns to a soft stop (maximum sensor output). Negative signal will be
converted into positive signal at MP6 (i.e.: negative signal = -0.5V; output test between MP15 and
MP6 = +0.5v). Refer to Theory 1 and 2 in Section 12.
Main board in central unit defective. Replace main board and
reset pressure channel.
Refer to Drawing 3 in Section 10 and
Procedures 3 and 4 in Section 11.