Metrohm 794 Basic Titrino - Manual (Page 145)

4.2. Diagnosis
794 Basic Titrino 141
pot.meter dV/dt  10?
• Turn knob ‘dV/dt’ to the right stop and press .
Test sequence:
a) In a first step, the frequency of the RC oscillator (analogue rate) is tested over a period
of 1 second.
b) In a second step, the frequency of the quartz oscillator (digital rate) is tested over a
period of 1 second.
c) If no error is found, after about 3 s it appears
motor-timer test o.k.
• Press .
diagnose press key 0...9
7 Analogue input test
• Press <7>.
analog input test 1...5
7.1 Examination of highly insulated measuring inputs
• Connect ‘Ind I’ measuring input to a voltage calibrator (e.g. Metrohm 773 pH simu-
lator) by means of a highly insulated cable (e.g. 6.2108.060). Set calibrator to 0 V.
• Press <1>.
Input 1 0.0 mV
Tolerance: ± 0.5 mV
• Set the calibrator voltage, on setting 'low ohmic' (with 773 = ~ 0.002 MΩ) to differ-
ent values (e.g. +1500 mV) and compare with the displayed value.
Tolerance (with ± 1500 ÷ 2000 mV) ± 1 mV. Be aware of the calibrator's tolerance.
• Set simulator to high ohmic condition (with 773 = 1000 MΩ).
The displayed reading may vary slightly only (with 1500 mV ≤ 1 mV)
• Press .
analog input test 1...5
• Disconnect simulator from ‘Ind I’ input and connect to ‘Ind II’ input.
• Press <2>.