Fluke NetDAQ 2640A, Service Manual

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Diagnostic Testing and Troubleshooting
Troubleshooting the Instrument
5
5-19
Command: MEAS?
Description: Takes a measurement on channel one and returns the measured value. This
command is new to the instrument.
Parameters: None
Response: <measurement> = IEEE-488.2 NR3 ASCII representation of a floating point
value: leading sign;
5 or 6 digits with embedded decimal point for 2645A and 2640A respectively,
padded
with leading and trailing zeroes if necessary;
“E”;
a signed exponent of -3, +0, +3, or +6.
For e115.67E+0.
An overload condition is indicated by a value of +001.00E+9 or -001.00E+9 in the
2645A, +001.000E+9 or -001.000E+9 for the 2640A.
Restrictions: Not allowed in calibration mode. If channel one is not configured, this
command generates an execution error and does not return a value.
Notes: While processing this query, the instrument does not return a response or a
prompt until the measurement has been taken.
The instrument generates a device dependent error if the measurement does not arrive
after 30 seconds.
Open thermocouples return a +999.99[9]E+9.
Troubleshooting the Instrument 5-19.
The following paragraphs describe an organized method of instrument troubleshooting.
The overall approach is to start with power-up self-test error codes and then proceed to
more and more detailed procedures. Begin troubleshooting with “General
Troubleshooting.” These procedures locate about 90% of the instrument faults. The
remaining faults require sleuthing that is beyond the scope of this manual. For these
cases, review Chapter 2 “Theory of Operation” and approach the difficulty in a logical
manner adapting the troubleshooting procedures, as required. As a last resort, contact the
factory or Fluke Service Center (see Chapter 6) for assistance.
General Troubleshooting 5-20.
General troubleshooting uses the instrument response to self-test as a clue to the fault
location. If the instrument completes self-test and displays an error code on the front
panel, refer to Table 5-10. If the instrument appears dead and will not even self test, refer
to Table 5-11. If the instrument passes self test but is not operating correctly, then refer
to “Troubleshooting the A3 A/D Converter PCA” for analog problems, and
“Troubleshooting the A1 Main PCA” for digital problems. For assembly and
disassembly procedures, see Chapter 3, “General Maintenance.”