WARNING
Extremely high, potentially lethal, RF voltages are present in the ATU-HP when an RF
input is being applied. Use extreme caution during maintenance or troubleshooting
inside the ATU-HP cabinet. Where possible, turn off the associated transmitter.
ATU-HP Technical Instruction Manual
Page 5-3
Section 5 System Level Troubleshooting
Issue 2.0
(e) If motor operation cannot be heard,
and the
L TUNING – MAX LIMIT
or
MIN LIMIT
LED is not on, check the
12V-A
LED. If the
12V-A
LED is on,
the motor is probably defective.
(f) Turn off the ac power applied to the
ATU-HP cabinet.
(g) Loosen/remove the two hex-head
(Allen-key) screws that secure the
motor to the motor chassis.
(h) Loosen the clamp from the drive shaft
and then pull the motor from the drive
shaft.
(i) With the motor partially removed,
unsolder the two white wires [# 15 from
B1 (+) and # 16 from B1 (–)] from
motor B1.
(j) Remove the defective motor.
(k) Install the replacement motor (Nautel
Part # ZAP29) by using the reverse
order of steps (g) through (i). Ensure
the inner coil and limit actuator are
positioned as described in step (d).
(l) Turn on the ac power applied to the
ATU-HP cabinet.
(m) Set the ATU-HP to
LOCAL
mode and
verify motor operation using the
L
TUNING – INCREASE
and
DECREASE
switches. Check that
L
TUNING -
MAX LIMIT
and
MIN LIMIT
LEDs can be turned on.
(n) Upon successful motor checks,
position the ATU tuning coil (using
L
TUNING – INCREASE
or
DECREASE
switches) so that the limit actuator is
facing the cabinet bottom (inner coil is
perpendicular to outer coil).
(o) Reinstall the ATU-HP’s front cover.
Turn on the associated transmitter.
5.3.3 Checking/Replacing the
Resistive Tuning Motor
There is no alarm that indicates the failure
of the ATU-HP’s resistive tuning motor.
The easiest way to check its operation is
by attempting manual resistive tuning
adjustments and listening for motor
operation. The resistive tuning motor
(A2B1) is located to the left of the fan
assembly at the bottom of the ATU-HP
cabinet (see Figure MD-1). Check and, if
necessary, replace a failed resistive
tuning motor as follows:
(a) Remove the ATU-HP’s front cover.
Turn off the associated transmitter.
(b) In
LOCAL
mode, check the operation
of the resistive tuning motor (A2B1) by
pressing and holding the
R TUNING -
INCREASE
(A1S5) or
R TUNING –
DECREASE
(A1S6) switch, assuming
the
R TUNING – MAX LIMIT
or
MIN
LIMIT
LED is not turned on.
(c) If motor operation can be heard or
movement of the limit actuator can be
seen, the motor is functional. If so, set
the ATU-HP to
REMOTE
, reinstall the
ATU-HP’s front cover and restore the
transmitter to its desired power level.
(d) If motor operation can be heard, but
the limit actuator does not move, check
the coupler between the motor and the
lead screw. If necessary, tighten the
coupler. Set the ATU-HP to
REMOTE
,
reinstall the ATU-HP’s front cover and
restore the transmitter to its desired
power level.
