Hach SIGMA 900, User Manual

Page: 62 / 94

Page 62
Troubleshooting
8837apdx_trouble.fm
Appendix A
Sigma 900 All Weather Refrigerated Sampler Troubleshooting Flow Chart
! DANGER !
AC power is exposed when Power Supply /
Thermal Conmtrol box is removed!
Cabinet Temperature Fault
Be sure door is shut tight, then wait 90 minutes and
check system diagnostics.
Cabinet temperature above setpoint
temperature range
(> se 1 degree C)
Is the compressor enabled?
(REFRIG = ON > 0 Minutes)
YES
Perform calibration
(refer to O&M manual,
Chapter VII)
Is the evaporator heavily frosted?
YES
NO
Is cabinet
temperature OK?
(setpoint ± C°)
yes
Is the "Evap Htr" LED
on in the PS/TC box?
Is the AC line voltage
present at TB4 in the
PS/TC box?
NO
Check terminal block
connections on PS/TC
assembly
Power Supply
Thermal Control
Assembly
Does evaporator
heater 'feel' warm?
CAUTION - MAY BE
EXTREMELY HOT!
yes
Was cabinet door ajar?
Check door gasket
Check evaporator heater
adherence.
CAUTION - MAY BE
EXTREMELY HOT!
Evaporator
Assembly
Evaporator
Assembly
Sampler
Controller
YES
Check terminal block
connections on PS/TC
assembly
NO
Reference
Temperature
Assembly
Power Supply
Thermal
Control
Assembly
NO
Is nominal 5 VDC
present at TP1 in
PS/TC box?
Metric
NO
NO
Check terminal block
connections on PS/TC assy.
YES
Sampler
Controller
NO
Power Supply
Thermal
Control
Assembly
Evaporator
Temperature
Assembly
Check terminal block
connections on PS/TC
assy.
YES
Power Supply
Thermal Control
Assembly
YES
YES