Metrohm 780 - Page 127

8 Troubleshooting – Messages – Maintenance
780/781 pH/Ion Meter, Manual
117
Message Situation Cause Remedy
limit error Direct measure-
ment, all modes
Set limit for primary or sec-
ondary measured value
exceeded
see Section 7.4
cal. interval
expired
pH and Conc
modes
Set calibration interval has
expired
Recalibrate electrode (see
Section 6.2.2 and 6.5.5)
cal.data out of
limits
pH calibration Determined calibration
data are outside limits de-
fined as calibration param-
eter
Accept calibration data with
<ENTER>
or reject them
with
<MODE>
; check
electrode, buffer or limits
under
6.2.2
Conc calibration • Determined slope is
outside limits of 80 –
105 % of theoretical
slope (59.16 mV per ion
charge [25°C])
• Sign incorrect for set
type of ion.
• Accept calibration data
with
<ENTER>
or reject
them with
<MODE>
• Check electrode, stand-
ards under 6.5.5
or check
ion type under 6.5.2
calibration OK pH calibration,
Conc calibration
Calibration has been con-
cluded successfully
Exit display with
<QUIT>
;
this happens automatically
after 30 s; calibration data
will be accepted
manual stop Various measur-
ing runs
Measurement has been
stopped manually
measuring
range exceeded
Various measur-
ing runs
• Electrode not immersed
in the solution
• Electrode not connect-
ed correctly
Remedy fault or change
mode
measured value
memory full
Saving measured
values in a direct
measurement
Attempt made to store a
further measured value
when 100 have already
been stored
Delete measured values
(see
Section 7.3)
plot data
overflow
Report output Data output is faster than
printer processing speed
Press
<QUIT>
and
• Increase time interval be-
tween measurements
• Increase time scale
• Reduce graph width
• Only output primary
measured value.
buffer not
defined
pH calibration pH of a buffers has not
been defined under Buff-
er type: own for the
given temperature
Enter missing value in tem-
perature table (see
Sec-
tion 6.2.2
)