9/15/06
888-2586-001
4-39
WARNING: Disconnect primary power prior to servicing.
Section 4 Overall System Theory
Platinum Z16HD+
4.6.4.1
Relays
There are three mechanical relays on the Low Voltage Power Supply Board assembly
A19. They are A19K1, A19K2 and A19K3. The relays are powered by +12Vdc from
the Life Support Board in the controller.
•
A19K1 activates the main AC contactor, K1. A19K1 is activated when the transmit-
ter is turned on and the “CONTACTOR_ON” signal from the Life Support Board
goes low. When activated, A19K1 supplies Phase A (or Neutral) to the coil of the AC
mains contactor K1 (and K3 in the Auxiliary cabinet for the single phase), which
then supplies AC to the PA power supply transformers.
•
A19K2 is activated by the same “CONTACTOR_ON” signal and supplies Phase B to
the exciter(s). Note that this means the exciter(s) will not have power until the trans-
mitter is turned on. Phase A (or neutral) also enters this board at J1-11 and connects
to the exciter(s) via J1-9 and J1-10. This input comes from the load side of the AC
mains contactor K1 and thus will only be present when the transmitter is turned on.
•
A19K3 is activated by the active low “FAN_SPEED_SELECT” signal from the Life
Support Board. A19K3 activates the fan speed select relay K2 mounted next to the
AC mains contactor on the cabinet wall. K2 is shown on the Overall System Block
Diagram in the HIGH fan speed position. When A19K3 pulls in so does K2 (not
A19K2).
Upon transmitter turn on, the fan will run at high speed for one minute, then will
normally run at the low speed until a fault occurs or there is a significant increase in
temperature detected by the controller. The blower motor is a 2 speed, single phase
motor. K2 simply directs the AC to the high or low speed windings on the motor. The
fan speed can also be manually set to HIGH speed or AUTO in the Configuration
Menus of the Diagnostics Display.
4.7
Cooling System Description
The transmitter is cooled by the single, two speed fan in the lower rear of the
transmitter. It uses a high volume, low velocity, air system. Air ducting for inlet air
should be well filtered and, if possible, at a slightly positive pressure. The exhaust air
ducting should cause very little or no back pressure due to the low velocity air system.
Air handling recommendations are shown on the Cabinet Outline Drawings in the
schematic package. There are air flow sensors on the IPA Backplane Boards which
sense airflow using a temperature differential between an ambient sensor and a biased
sensor. If the airflow is reduce to approximately 25% the fan will be switched to high
speed. If this fails to increase the airflow the transmitter will be shut off. There are also
many other temperature sensors in the transmitter which are protecting individual
circuits and systems. These are best described by looking at the faults which occur as a
result of the over-temperature condition. These are discussed later in this section or in
Section VI, Troubleshooting.
Summary of Contents for Platinum Z16HD+
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