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TROUBLESHOOTING & REPAIR PROCEDURES
•
If D1 on the Relay board is flashing and the status indicator for the output in
question (Heater power, Valve Drive, etc.) toggles properly using the Signal I/O
function, then the associated control device on the Relay Board is bad. Several
of the control devices are in sockets and can be easily replaced. The table below
lists the control device associated with a particular function.
11.5.5.1. Pressure Sensor Assembly
The pressure/flow sensor PCA, located adjacent to the Sample Pump, can be
checked with a Voltmeter using the following procedure which, assumes that the
wiring is intact, and that the Motherboard and the power supplies are operating
properly:
1. For Pressure related problems:
•
Measure the voltage across C1 it should be 5.0 ± 0.25 VDC. If not then the
board is bad.
•
Measure the voltage across TP4 and TP1. With the sample pump disabled it
should be 4500mV ±250mV. With the pump energized it should be
approximately 200mV less. If not, then S1, the pressure transducer is bad,
the board is bad, or there is a pneumatic failure preventing the pressure
transducer from sensing the absorption cell pressure properly.
2. For Flow related problems:
•
Measure the voltage across TP2 and TP1 it should be 10.0 ±0.25VDC. If not
then the board is bad.
•
Measure the voltage across TP3 and TP1. With proper flow (800 sccm at the
sample inlet) this should be approximately 4.5V (this voltage will vary with
altitude). With flow stopped (sample inlet blocked) the voltage should be
approximately 1V. If the voltage is incorrect, the flow sensor is bad, the
board is bad or there is a leak upstream of the sensor.
260
Table 11-5: Relay Board Control Devices
Function
UV Lamp Heater
O3 Gen Heater
All Valves
Model 400E Ozone Analyzer
Control
In Socket
Device
Q2
No
Q3
No
U5
Yes
Instruction Manual
P/N 04316 Rev: B
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