Metrohm 746 VA Trace Analyzer - Manual (Page 548)

7.6 Diagnosis
746 VA Trace Analyzer / 747 VA Stand
7-49
7.6 Diagnosis
7.6.1 General
The 746 VA Trace Analyzer and 747 VA Stand are very precise and dependable in-
struments. Thanks to their rugged construction, it is highly unlikely that external me-
chanical or electrical influences will have an adverse affect on their functions.
Although the appearance of a fault in the instrument can not be excluded with cer-
tainty, it is far more likely that malfunctions will be caused by faulty operation or
handling or through improper connections and operation with third-party devices.
It is always advisable to isolate the fault with the diagnostic program as this is sim-
ple and easy to run. The customer need call Metrohm service only when the instru-
ment really has a fault. Moreover, he can then provide the service engineer with
much more detailed information using the numbering in the diagnostic program.
When making inquiries, always quote the serial number 77 (see section 2.1) and
program number (see section 5.3.1) and any error displays which may have ap-
peared.
Procedure
• If a malfunction occurs, the directions of the appropriate diagnostic step
(see following test list) must be followed. The ensuing reactions of the VA
Trace Analyzer must be compared with the descriptions in the diagnostic
step.
• If the instrument does not show the expected reaction (”no” case), the ap-
propriate diagnostic step must be repeated to exclude an operating error.
It is highly probable, however, that multiple wrong reactions indicate a
malfunction.
Test list
1. Prepare instrument for diagnostic test section 7.6.2
2. Check thermal printer section 7.6.3
3. Check RS232 interfaces section 7.6.4
4. Check control lines section 7.6.5
5. Check keypad section 7.6.6
6. Check VA Stand (perform measurement section 7.6.7
routine with polarogram simulator)
Instruments needed
Necessary only if RS232 and control lines are also checked:
• 3.496.8550 Test plug (to connection 'Control lines')
• 3.496.8480 Test plug (to connection 'RS232')