Metrohm 781 pH/Ion Meter - Manual (Page 135)

8 Troubleshooting – Messages – Maintenance
780/781 pH/Ion Meter, Manual
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RAM Test
This test checks the condition of the instrument memory without altering
its contents. A successful test is concluded with the message ' ram
test ok '.
AD-Converter Test
The electronic components of the analog-digital converter are checked.
At the end the two messages ' ADC EEPROM Test ok ' and ' ADC Int.
ok x mS ' should appear. Instead of ' x ' the message should contain a
number between 15.0 and 25.0.
LCD Display Test
With this test you can check that the LCD display is functioning proper-
ly. It consists of a sequence of individual tests which can be switched
forward with . The test can be halted with and can-
celed with .
Key Test
The correct functions of all the instrument keys can be checked here.
After the start a 3-fold beep will be heard (so that you can also test this
straight away) after which the instrument will respond to the pressing of
each key by displaying the corresponding key code. However, the
key will still switch off the pH/Ion Meter. This test is termi-
nated by pressing the key twice.