Model 405 nm NO
2
/NO/NO
x
Monitor Manual Rev. D
29
9.
TROUBLESHOOTING
If the instrument fails to operate correctly, common problems can be identified and
corrected using Table 9.1. If the problem cannot be easily corrected, please contact
Customer Service at 2B Tech via our web ticketing software at:
www.twobtech.com/techsupport.htm
Alternatively, you can email us at
273-0559. If we mutually determine that the instrument cannot be repaired onsite, we
will provide you with a Return Authorization number and a short form to be filled out
and returned to our Service Department along with the instrument.
The figures following Table 9.1 provide a
“guided tour” of the Model 405 nm
NO
2
/NO/NO
x
Monitor
™ so that critical components and connectors may be easily
identified. A list of serviceable parts is provided in Section 12 at the end of this manual.
Table 9.1. Troubleshooting the NO
2
/NO/NO
x
Monitor for performance problems.
Problem/Symptom
Likely Cause
Corrective Action
Instrument does not turn
on.
Power not connected
properly or circuit breaker
open.
Power cable not connected to
circuit board.
Check external power
connection for reverse
polarity or a short and wait a
few minutes for the thermal
circuit breaker to reset.
Remove top cover and
disconnect and reconnect
power cable to circuit board.
Instrument turns on then
powers off.
Burned out air pump.
Remove top cover and
unplug air pump. Turn
instrument on; if it remains
running, then the air pump
motor is burned out and
shorting. Replace air pump.
Display is blank or
nonsense.
Bad connection of display to
circuit board.
Remove top cover and
reconnect display to circuit
board. Check solder
connections to display.
Cell temperature reads low
by several 10’s of degrees.
Absent or loose connection of
temperature probe cable to
circuit board.
Remove top cover and
reattach connector to circuit
board.
