Teledyne 402REU - Hydrocarbon analyzer - Manual (Page 13)

Total Hydrocarbon Analyzer Operational Theory
2-1 Teledyne Analytical Instruments
Operational Theory
2.1 Electronics
The analyzer features semiconductor circuitry throughout. Integrated
(IC) circuits are employed in the highly sensitive electronic circuits of the
instrument to reduce circuit component requirements and increase reliabil-
ity. Aside from the necessary power transformers, three fuses, and electri-
cal controls, all circuitry is mounted on plug-in type printed circuit cards.
The circuitry has been sectionalized so that spare circuit cards can be
employed without the use of expensive test equipment or the services of a
highly-trained technician. With spare circuit cards available for replace-
ment, you will only need a multimeter to isolate and remedy an electronic
malfunction.
All the electronic PC board units (except the electrometer-amplifier)
plug into an interconnecting unit called the motherboard. See Figure 2-1
for motherboard location.
WARNING: The PCBs in the 402R-EU contain dangerously high
voltages. Ensure that all power to the instrument has been
removed before disconnecting or handling any of the
PCBs.
(See Section 1 Page VII: "PROCEDURE FOR RE-
MOVAL OF INTERNAL INACCESSIBLE SHOCK HAZARDS").
The only electromechanical devices used are the control and fuel shut-
off relays in the flame guard circuit.
The isothermal chamber components including the detector cell are
interconnected with the electronics chassis by means of plug-in cables.
The bulk of the electronic circuitry is located behind the hinged door
of the analyzer. Access to the interior of the analyzer is gained by rotating