ATI
Q46D-ODO Optical D.O. System
Part 9 – Troubleshooting
62
O&M Manual
Rev-J (8/17)
2. If analyzer does not appear to power up (no display), remove
power and check removable fuse for continuity with a DVM.
3. Using a DVM, check the voltage across the BLUE and WHITE
wires coming from the power supply board in the base of the
enclosure. FIRST, disconnect any wiring going to Iout#1. Then,
verify voltage across these wires is about 16-18 VDC when still
connected to the terminal strip on the front half of the enclosure.
If the BLUE and WHITE wires are not connected to the terminal
strip on the front half of the enclosure, the voltage across them
should measure about 29 VDC.
4. If analyzer does power up with a display, use the “Simulate”
feature to check operation of the analog outputs (and relays
contacts with a DVM.)
5. Check sensor power circuits. With a DVM, verify between -4.5
and -5.5 VDC from sensor connection terminals WHITE (+) to
BLACK (-). Then verify between +4.5 and +5.5VDC from
GREEN (+) to BLACK (-).
6. Check TC drive circuit. Place a wire-short between the RED
and BLACK sensor terminals. With a DVM, measure the
voltage between the BLACK (-) and BROWN (+) sensor
terminals to verify that the TC drive circuit is producing about -
4.6 to -5.5 VDC open-circuit. Remove DVM completely and
connect a 1000 Ohm resistor across the BLACK to BROWN
terminals. The temperature reading on the front LCD should
display approximately 0°C and the dissolved oxygen reading
should display approximately 0 ppm.
9.31 Display Messages
The Q46 Series instruments provide a number of diagnostic
messages which indicate problems during normal operation and
calibration. These messages appear as prompts on the secondary
line of the display or as items on the Fault List.
