4-22
888-2463-001
3/6/08
WARNING: Disconnect primary power prior to servicing.
Diamond Series™
Section 4 Theory of Operation
OFF locally in the event of a GUI failure. This logic-L command is inverted and
becomes the MASTER ON/OFF-H pulse to the output driver U36 to enable/disable the
Modules. The MASTER ON/OFF also goes through the CPLD (complex
programmable logic device) U39 to create the system level command to turn on the fans
and power supplies.
Both the micro and the CPLD have the same control and protection functions, either can
control the cabinet. The micro is monitored by the CLPD watchdog circuit. Normally
the micro will control and protect the cabinet, but when the micro is faulty, the CPLD
will take over the cabinet control and protection.
External One-shots U44 stretch their input level change into a 10ms ON or OFF pulse
required by the system. The enable pulse from the CPLD pin 44, will go from H to L to
turn the transmitter OFF, LOW to HIGH will turn the transmitter ON. The CPLDs’
internal logic will disrupt the turn on of the transmitter with the System OFF at U39-13
if any faults or interlocks are present.
The CPLD also has a watchdog circuit. The microprocessor pulses watchdog chip U45
faster than the time period on the one-shot. Its’ Q output will stay in a stable condition
as long as the input pulse train continue. If they stop, due to a micro problem, the one-
shot time period will expire and send the MICRO_FAULT pulse to the CPLD which
will transfer control to the CPLD logic.
The one-shots will be reset when the transmitter is first turned on. The time it takes
C238 to charge will hold the one-shots in the clear state.
4.7.2.12 EPROM U22
All non-volatile parameter storage takes place in U22. EPROM U22 is a non-volatile
storage for all status and calibration programming.
4.7.2.13 Module Phasing Control
The microprocessor controls the PA Module phasing through synchronous serial
interface at DAC 1 and DAC 2. The digital to analog converters U4 and U9 will control
the phase adjustment (+ or -) of the PA Modules in the cabinet depending on the reject
sample from each module. In the event of a DAC failure, the 10K/12.1K resistor ladder
puts the phase adjust voltage at mid scale to provide zero degrees phase adjustment.
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