User's Manual

VI-1
Section VI – Monitor and Control System
Control Board Overview (Series II-rev I)
The control printed circuit boards (PCB) are located at the front of each enclosure connected directly
to the back of the liquid crystal displays (LCD) and are identified as Series II – rev I PCBs. The main
purpose of the Series II - rev I PCB is to monitor the RF power and the DC supply voltages in the power
amplifier and filter enclosures and to monitor just the DC supply voltages in the power supply
enclosure. In all cases, a DC voltage proportional to the parameter being sampled is conditioned,
protected, buffered, and then run into an analog-to-digital converter (ADC) where software processes
the signal. The software processing determines if the parameters are within the predetermined safe
operating levels and displays the parameters on the LCD for monitoring purposes. The Series II - rev I
PCB can be broken apart into (5) main component areas: the power supply, interface, signal
processing, display, and microcontroller. Schematics are found later in this section.
Power Supply Components
There are (4) power supply voltages generated on the Series II – rev I PCB:
1. +5Vdc for all logic and general purpose PCB supply voltage.
2. +4Vdc for the LED backlighting on the LCD
3. -4Vdc for the contrast voltage required by the LCD
4. +5Vdc for the directional coupler supply
The +5Vdc is generated from a small switching power supply comprised of C101, C102, D102, L101,
and U101. This power supply accepts DC input voltages up to 40Vdc (unless U101 is an HV option,
then the maximum input voltage is 60Vdc) and outputs +5Vdc at up to 1Adc. This voltage is always on,
as the ON/OFF pin on U101 is hard-wired to the on configuration. C103, L102, and C104 form a noise
choke to help filter and switching noise or RF noise that may radiate onto the control circuit board.
The +4Vdc is generated from a small switching power supply comprised of components C105, C106,
D103, L103, and U102. This power supply accepts DC input voltages up to 40Vdc (unless U102 is an
HV option, then the maximum input voltage is 60Vdc) and outputs +5Vdc at up to 1Adc. The voltage
then gets dropped down to +4Vdc through R101. This backlight voltage can be turned on and off via
the ON/OFF pin on U102. The PCB is setup in a manner that allows this voltage to be hard-wired on all
the time or controlled from the microcontroller through latch U111. This selection is made with jumper
J102.
The -4Vdc is generated using a switched capacitor voltage converter design, using components C109,
C110, R102, R103, U104, and VR101. U4 accepts +5Vdc from the general purpose +5Vdc supply and
generates -5Vdc. This voltage then gets dropped across the voltage divider (R102, R103) to generate
the contrast voltage specific to the LCD that is installed in the system.
The voltage required by the directional coupler is generated with a standard linear voltage regulator,
U103. C107 and C108 helps clean up any ripple or noise that might be on the output voltage. In the
standard configuration, where the directional coupler requires 5Vdc, the 5Vdc is simply taken from the
U101 filtered power supply output.