Series 4060 | Maintenance | |
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5.5 Printed Circuit Board Descriptions
The electronics circuitry of the analyzer is designed with the latest integrated circuit technology. The individual circuits which are required to process the incoming signal and condition it to provide the various outputs, alarms, indicators, etc.,
5.5.1 Flame Guard and Anode Power Supply PCB
Schematic No.
Anode Power Supply: The high voltage anode power supply components are mounted on the flame guard and anode power supply printed circuit board. High voltage regulation is achieved through the use of zener diodes. The simplicity of this circuit’s design can be attributed to the extremely low current demand of the anode circuit. The positive output voltage is nominally 125 volts. Output tolerance is ±10 volts from the specified 250 volts, due to variation in components from unit to unit.
Flame Guard Circuit: A
The controlling thermistor is located within the upper section of the cell assembly. The electronic circuit components and relays are mounted on the same printed circuit board as the anode power supply. the indicator light on the control panel.
The thermistor is located in the circuit so that it controls the input of comparator. The circuit is factory set so that with the flame burning, the output of comparator is low. The microprocessor senses the low input and in turn sends 5VDC to turn on Q1, this holds the relay energized. When energized, the relay extinguishes the Flame Out indicator light. Conversely, if the flame goes out, bias to the switching transistor is lost, the relay drops out, and the Flame Out light receives power through normally closed contacts.
During ignition, the flame heats the thermistor, holding the relay in the energized condition and the indicator light off. If the Flame Out light comes on as the analyzer returns analyzing mode, then the flame is not burning, and the ignition procedure must be repeated.
Teledyne Analytical Instruments | 71 |