Teledyne 402REU - Hydrocarbon analyzer - Manual (Page 38)

Chapter 5 Model 402 R-EU
Teledyne Analytical Instruments 5-4
2. Apply procedure given in Section 1, Page VI of this manual,
then unplug P3 from J3 of the anode-igniter cable.
3. Reconnect the mains (line) cord to the 402R-EU and turn it ON.
4. Measure the voltage between socket "3" of J3 and ground and
then reapply the same procedure as provided in section 1, page
VI of this manua.
5. If the voltage was 250±22VDC, then check the anode-ignitor
cable and the sensor for low electrical resistance to ground or
other problems. Else, if the voltage was not 250±22VDC, then
replace the flame guard and anode power supply Pc Board.
WARNING: Do not touch capacitor C1 or C2, resistor R1 or R2, di-
odes D1, ZD2 or ZD3 or their related circuit foils. A shock
hazard may exist.
Note and follow the turn off procedure
given in Section 1 Page VII: "PROCEDURE FOR REMOVAL OF
INTERNAL INACCESSIBLE SHOCK HAZARDS" .
Carefully remove the circuit board without touching any connections
which might lead to C1 or C2. After removal, discharge the two capacitors
by placing a jumper wire across each.
3. The anode voltage may also disappear or be greatly diminished
when condensation inside the sensor has occurred, shorting the
ignitor to the sensor body across the wet insulator. This usually
occurs when the flame is turned on, if the sensor has not been
preheated for at least 1 hour.
5.1.3 Electronic Stability
If the checks outlined above indicate that conditions are normal, allow
the analyzer to run electronically with the collector cable disconnected for
several hours in the lowest range, and with the zero control adjusted so that
the recorder is reading midscale. If all is normal electronically, a noise-free
(pen width) recording, showing absolutely no instability, should be ob-
tained for as long as the analyzer is allowed to run in this configuration. If
the recording obtained is noisy or erratic, replace the electrometer-ampli-
fier PC board.
5.1.4 Printed Circuit Board Replacement
Whenever the differential power supply temperature controller or
electrometer-amplifier printed circuit boards are replaced (or repaired),
instrument performance should be rechecked. The replacement circuit
boards are tested and adjusted at the factory before they are sent, and in
most cases, no recalibration will be required.