Teledyne 7300a - NDIR analyzer - Manual (Page 78)

5 Maintenance Model 7300A
5-8
Teledyne Analytical Instruments
C. Meter reads Negative (a) ZERO control may be
misadjusted.
(with zero gas flowing Adjust control to bring indication
through analyzer) up to zero. (refer to Section 4).
(b) If zero indication unattainable with
ZERO control centered, monitor TP6
on preamp board.
(c) Check that infrared source is
operating. If no light check source
element resistance and connections.
D. Meter Up Scale or (a) Redo full calibarion.
Overscale
(b) Check for obstruction in sample
beam path.
(c) Check for excessive moisture in
plumbing and sample chamber. Clean
and replace sample chamber.
E. Insufficient Span (a) Recheck zero for excessive off-
Control (with span gas) set.
(b) Check modulation factor using
certified span gas.
F. Noisy or Erratic The most eommon sources of
Operation noises are:
(a) Reduced output of infrared source
(5v, 110 ma each) or replace as
necessary.