S
ERVICE AND
M
AINTENANCE
7-6
June 1997 Rosemount Analytical 748213-P
Model 755R Oxygen Analyzer
7.3.2 P
HOTOCELL
If the photocells are on, observe through the photocell alignment hole. The image
should be steady. Disconnect the line power and observe the image when you
reconnect the power. It should come up from the side and seek a position that equally
illuminates the photocells.
7.3.3 S
USPENSION
Turn electrical power to instrument OFF. Remove optical bench assembly (see Figure
7-1A). With 100% nitrogen flowing through the analyzer, note position of the
suspension. Then admit air and note response of the suspension. It should rotate
clockwise as viewed from the top, and to the right as viewed though the window.
Failure to rotate indicates that the suspension has been damaged and detector
assembly must be replaced. See Section 7.4.3.
If the suspension has been changed, the cause may be improper operating
conditions.
7.4 REPLACEMENT OF DETECTOR/MAGNET COMPONENTS
7.4.1 S
OURCE
L
AMP
R
EMOVAL
/I
NSTALLATION
The source lamp is held in the optical bench assembly by a set screw (see Figure 7-
1B). The two lamp leads are connected to J12.
The red line on the lamp base must align with the set screw (see Figure 7-4A). The
base of the lamp should extend from the hole approximately 1/4 inch. Tighten set
screw when lamp is aligned.
Realign the photocell per Section 7.4.2.
7.4.2 P
HOTOCELL
R
EMOVAL
/I
NSTALLATION
Refer to Figure 7-1B. Note location of photocell leads in connector J12. Remove
leads. Remove photocell lock screws (2), slide photocell out.
Reverse the removal procedure for installation. Align photocell (see below).
A
LIGNMENT
The adjustments in this procedure are made on the Control Board. With zero gas
flowing:
