Nautel XR12, Руководство по устранению неисправностей, Страница: 50 / 283

XR12 Troubleshooting Manual Responding to alarms
Page 1-30 Issue 3.0 2009-07-28
Test cable connection
Connect the RF power module to be tested to the transmitter's test circuit as follows:
1. Connect the test load (Nautel part # 176-5720-01) to
J3
of the RF power module.
J3
is the
upper connector on the rear of the power module (see Figure 1.4 on page 1-22 ).
2. Connect P4 of the test cable (Nautel part # 202-5010) to J2 of the RF power module to be
tested, noting that J2 is the lower connector on the rear of the power module.
3. Connect P2 of the test cable to J5 (
RF DRIVE/TEST
) of the transmitter's RF drive buffer PWB
(A24).
4. Connect P1 of the test cable to J11 on the transmitter’s distribution PWB (A16).
5. Connect P3 of the test cable to the module's J1 connector, noting that J1 is located on the
bottom of the module near its front. The module will have to be placed on a table to allow
access to J1. Ignore all alarm indications at this time.
WARNING:
Although the module under test is connected to low-level voltages,
its rf output can still exceed 500 volts peak-to-peak. This voltage can
cause painful rf burns. Avoid contact with the test load while the
module is operating on the test circuit.
NOTE:
The test circuit's B+ supply (48 V) is protected by a thermistor (PTC). Measure the dc voltage
on modulator fuse A14F1 once the test cable's P3 is connected to the module's J1 connector. If
there is a shorted modulator installed in the module, the voltage reading will be near 0 V.
Repeat all of the checks in
“Resistance measurements” on page 1-27 .
The test circuit’s RF drive supply is protected by a thermistor (PTC). Measure the dc voltage on
RF drive control PWB fuse A1F1 once the test cable’s P3 is connected to the module’s J1
connector. If there is a problem with the RF drive section of the RF drive control PWB, the
voltage reading will be near 0 V. Repeat all of the checks in
“Resistance measurements” on
page 1-27 .