9/15/06
888-2586-001
6-25
WARNING: Disconnect primary power prior to servicing.
Section 6 Troubleshooting
Platinum Z16HD+
reading. If the thermistor circuit becomes open, the detector input goes high which
gives a cold temperature reading. This leaves the device to which the thermistor is
connected, unprotected from an over-temperature condition. Once this fault is detected
it will stay active in the log until the Fault Log is reset.
NOTE:
If one of the thermistors or connecting cables is shorted, a temperature fault for
the device it is connected to will be registered in the Fault Log, not a THER-
MISTOR fault. A shorted thermistor or cable will give a very hot reading which
will not change, about 155° C or higher. A shorted thermistor on one of the PA
ISO resistors will cause a PA_ISO_OT fault and the transmitter will be shut off
(see PA_ISO_OT under PA Controller Faults).
6.12.1.1 Troubleshooting for a THERMISTOR fault:
a.
First, locate the problem thermistor by systematically looking at all of the temper-
ature readings. One of them will show a # sign instead of a temperature. The tem-
peratures to look for include:
1.
IPA Temps - IPA_AB1 and IPA_AB2. The thermistor is located on the IPA
right next to the FETs.
2.
PA Temps for A1-A8 and B1-B8. The thermistor is located on the PA right
next to the FETs.
3.
ISO Resistor Temps for A1-A8 and Az / B1-B8 and Bz. These are all
located on the Isolation Boards.
4.
System ISO Temps - ISO_AB and ISO_CD. Located on the 3dB hybrids
which combines the Z-Planes. It is above the PA Modules under the rectan-
gular cover. The sense line (BNC coax) comes out the top of the box.
5.
System ISO Temp - ISO_ABCD. Reject load located on the front corner of
the Hybrid combiner in the power supply compartment.
6.
Power Supply Temps - PS1 and PS2. These sensors are part of a screw con-
nector bolted to the top of the power supply heatsink (it is covered with
heat-shrink tubing).
b.
Once the problem thermistor is located, shut off the Low voltage supply with
CB1 in the rear of the transmitter. Use an ohmmeter to check the resistance of the
thermistor. It should be from 10K to 50K ohms (just not shorted or open) depend-
ing on which thermistor is being checked.
Summary of Contents for Platinum Z16HD+
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