Larcan MXI1002U Digital Television Translator User Manual Heading 3
Larcan Inc Digital Television Translator Heading 3
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Amplifier Chassis PUB
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Power Amplifier PUB
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Controller PUB
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Operations/Maintenance PUB
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Combiner PUB
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Power Supply PUB
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Amplifier Control PUB
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![AMPLIFIER CONTROLLER BOARD REV.3 Note the AGC voltage from the LCD, if it is near to a value of 0 (i.e., under 0.1V), then there is no AGC action left and the power cannot be raised any further. If the amplifier power is under 100%, then check the RFL power level and CUTBACK voltage to verify that the amplifier is not reducing power to protect from a VSWR condition. The cutback circuit checks the level of reflected power as displayed on the LCD screen above [RFL=00.1%]. If this reflected power is greater than 1%, the cutback circuit automatically reduces the amplifier forward power to protect the devices. This indicates a mild VSWR condition such as may be caused by an icy antenna. The cutback function is a safety protection and is therefore permanently in circuit and cannot (or should not) be disabled. If the VSWR condition worsens such that reflected power exceeds 10% of forward power, the MXi shuts the transmitter down. The MXi has built-in VSWR protection to prevent damage to the amplifier from excessive power being reflected back from the output system. This VSWR protection becomes operational when reflected power exceeds 10% of forward power. The system shuts down the amplifier for a few seconds and then tries to restart again. This is done to check if the VSWR was a temporary condition that could have been caused by a lightning strike nearby. The LCD shows the TRIP status light on the third row of the LCD to indicate that a VSWR trip had occurred. If the condition persists such that three VSWR trips occur within 1 minute, the system completely shuts down. The LCD will then illuminate the L/O (Lockout) status light on the LCD to show that a Lockout has occurred. 2.5 2.5.1 INTERLOCKS Interlocks on the MXi amplifier can be divided into two different types: hard interlocks that shut down the amplifier without any CPU intervention and soft interlocks that are generated by the CPU chip in response to abnormal system parameters. Hard Interlocks There are hardware interlocks that directly affect the ON/OFF relay K1 by removing the +12V arming voltage on its coil and preventing it from turning on. There are four of these interlocks as follows: 2.5.1.1. Amplifier Thermal Heatsink thermal opens if heatsink temperature is too high. Dry Contact across Connector J9 pins 5 and 6. 2.5.1.2. Transmitter Switching Interlock provided for an external Transmitter Switching unit to shut down the Transmitter. Dry Contact across Connector J7 pins 1 and 2. When there is no transmitter switching, jumper E6 defeats this interlock. 2.5.1.3. External #1 Interlock supplied for customer use such as RF system interlock or RF Load. Dry Contact across Connector J9 pins 1 and 2. Parallel contact provided across J6 pins 14 and 15, only one of J6 or J9 is required. If not used, then this contact should be shorted out externally. 2.5.1.4. VSWR Relay K2 Contact from VSWR Trip relay K2 pins 11 and 13. Contact will be closed (OK) if there is no VSWR condition. Contact will open whenever a VSWR is detected. Note: Jumper E17 disables this interlock, this is for setup only. PUB11-017 Rev 1 Dec 8, 2011 11-017-8 Amplifier Controller Board Rev.3](https://usermanual.wiki/Larcan/MXI1002U.Controller-PUB/User-Guide-1708505-Page-10.png)
![AMPLIFIER CONTROLLER BOARD REV.3 5 5.1 CIRCUIT DESCRIPTIONS MC68HC908 MICROPROCESSOR The Motorola MC68HC908GT microprocessor (often referred to as the CPU or HC08) performs all of the control interface and communications in the MXi transmitter system. It is a 44-pin surface mount PLCC type device that is permanently soldered to the circuit board and is not field serviceable or easily replaced without special surface mount tooling. A brief description of the part is given in this section and a portion of the manufacturer’s documentation is given in Appendix A. More detailed information on this part can be obtained from the Motorola web site. The HC08 chip used in the MXi can come with either 8K or 16K bytes of non-volatile flash memory, which can be erased and reprogrammed to allow updating of software code or system parameters. The MXi code is typically smaller than 8k and so would fit in either size of Flash memory. The HC08 chip has a dedicated serial input pin designated as the BDM (Background Debug Mode) port that is used to program the internal Flash memory and for debug testing. The MXi is programmed at the factory and it is not expected that reprogramming would need be done in the field, although it is possible to do with the proper software. System parameters and status that need to be retained during power failures (such as the LOG entries) are also stored in the Flash memory. Most of the external pins on the HC08 are configured as programmable Input/Output (I/O) ports, where the software program determines whether a certain pin is to be configured as either an input or output. The pins on the HC08 are grouped together in sets called PORTs. These Ports will have eight pins (or fewer) to support the byte wide data path in the CPU. Port A is used for general system inputs and outputs. Port B is used as an eight-channel A/D converter to measure system telemetry values. Port C is used for general system inputs and outputs. Port D assigns four pins for the synchronous serial port (SPI) with the other four pins used for system inputs. Port E assigns two pins as a serial communications port (SCI), one pin is the external CPU clock and the other two pins used for general system inputs and outputs. The definition of each Port pin is as follows: PORT A PA0 Input or Output Jumper E3 configures as I/P or O/P PA1 Input Remote Control ON Command PA2 Input Remote Control OFF Command PA3 Output Select enable for Serial NvPot U16 PA4 Input Front Panel ON Command PA5 Input Front Panel VSWR RESET Command PA6 Input 50V Power Supply OK Status PA7 Input Remote Control VOR Status PORT B PB0 Telemetry Temperature of Heatsink [Optional] PB1 Telemetry Power Supply Current PB2 Telemetry Power Supply Volts PB3 Telemetry Cutback Volts [Scaled at half the actual value] PB4 Telemetry AGC Volts [Scaled at half the actual value] PB5 Telemetry RF Aural Power [from RF detector - Optional] PB6 Telemetry RF Reflected Power [from RF detector] PB7 Telemetry RF Forward Power [from RF detector] PUB11-017 Rev 1 Dec 8, 2011 11-017-19 Amplifier Controller Board Rev.3](https://usermanual.wiki/Larcan/MXI1002U.Controller-PUB/User-Guide-1708505-Page-21.png)
![AMPLIFIER CONTROLLER BOARD REV.3 PORT C PC0 Output Remote Status – Error PC1 Input DipSw #1 PC2 Input Power Supply (Relay K1) ON Status PC3 Input DipSw #2 PC4 Input External #1 Interlock PC5 Output VSWR Reset Control PC6 Output PS ON Ctl +12V out [could be 24V too] PORT D PD0 SPI SS Used by UART PD1 SPI MISO Used by UART and NvPot PD2 SPI MOSI Used by UART and NvPot PD3 SPI SCLK Used by UART and NvPot PD4 Input Fan#1 Status, Active Low PD5 Input Fan#2 Status, Active Low PD6 Input Fan#3 Status, Active Low PD7 Input Fan#4 Status, Active Low PORT E PE0 SCI Transmit Data Used by LCD PE1 SCI Receive Data Used by LCD PE2 O/P Remote Status – Remote Mode PE3 Input VSWR Trip Status PE4 System Main CPU Clock – 4.9152MHz The HC08 provides two separate serial interfaces to external components, these are the synchronous peripheral interface (SPI) and the serial communications interface (SCI). The SCI implements the standard three-wire serial port (Rx Data, Tx Data and Ground) that would interface to a typical computer port. The baud is set at 9600. The baud is derived from the system oscillator clock at 4.9152MHz. This frequency is recommended by the manufacturer to easily obtain the most common bauds. The SPI implements a four-wire clocked serial port that has four signals, Slave Select (SS), Master Out Slave In (MOSI), Master In Slave Out (MISO) and Serial Clock (SCLK). The HC08 is always set as the Master who initiates all serial communications. The SPI port is used to communicate with the MAX3110 UART (U2) and the DS1867 NovPot (U16). The HC08 will send out it data stream from the MOSI line and reads any responses from the external (Slave) devices via the MISO line. The SCLK is a serial clock (set for around 64K baud) that synchronizes the data transfer. The presence of this clock allows must higher data rates than the asynchronous SCI serial protocol. The SS line is a select that enables the MAX 3110 UART when low. A second individual select line from Port A (pin PA3) is used to select the DS1867 NovPot. 5.2 POWER SUPPLY VOLTAGE AND CURRENT MONITORING For the following description, refer to Figure 8 (Sheet #2 of the Schematic) in the upper section of the drawing for the power supply monitoring circuitry. In the case of a MXi802 or MXi1002 the first section describing the on-board current sensor is for reference only since sensing is done in the power supply chassis. PUB11-017 Rev 1 Dec 8, 2011 11-017-20 Amplifier Controller Board Rev.3](https://usermanual.wiki/Larcan/MXI1002U.Controller-PUB/User-Guide-1708505-Page-22.png)
