62
MODEL SOLU COMP II
SECTION 8.0
TROUBLESHOOTING
8.5 TROUBLESHOOTING WHEN NO ERROR MESSAGE IS SHOWING — GENERAL
8.5.1 Current Output Too Low.
Load resistance is too high. Maximum load is 600
Ω
.
8.5.2 Alarm Relays Do Not Work
A. Verify the relays are properly wired.
B. Replace power supply PCB (PN 23818-00)
8.5.3 Display is Unreadable.
While holding down the MENU key, press
"
or
'
until the display has the correct contrast.
8.6 SIMULATING INPUTS — DISSOLVED OXYGEN
To check the performance of the analyzer, use a decade box to simulate sensor current.
A. Connect a decade box to the analyzer as shown in Figure 8.1.
B. Set the decade box to the resistance shown in the table.
C. Note the sensor current. With the main display showing press
'
until the sensor current screen is displayed.
D. Change the decade box resistance and verify that the correct current is shown. Calculate current from the
equation:
current (
µ
A) =
Problem
See Section
Current output is too low
8.5.1
Alarm relays do not operate when setpoint is exceeded
8.5.2
Display is unreadable — too faint or all pixels dark
8.5.3
Sensor
Polarizing voltage
Resistance
Expected current
499A DO
675 mV
34 k
Ω
20
µ
A
499A TrDO
800 mV
10 k
Ω
80
µ
A
Hx438 and Gx448
675 mV
8.4 M
Ω
80
µ
A
voltage (mV)
resistance (k
Ω
)
FIGURE 8-1. Decade Box Connection
