Fluke 2680A Service Manual page 174

268XA
Service Manual
Error
Code
7 Module 1
Procedures
Incomplete.
8 Module 1 A/D
failure.
9 Module 1 zero
offsets test failed.
6-28
Table 6-9. Relating Selftest Errors to Device Problems (cont)
Error Code Suspect
Description Assembly
Module
PCA
A/D
Converter
and DIO
PCA
A3 A/D
Converter
PCA
Error Code
Discussion
Background Each module of the 2680A/2686A
contains its own calibration constants on the A/D Power
daughter card. The A/D U7 FLASH memory device
contains the calibration constants. The calibration
constants are used by the A/D converter.
Failure For this error to occur, you may have started a
calibration routine and then didn't complete it. When you
start a calibration routine, it sets a "start" flag; when you
complete a calibration routine, it sets a "finish" flag. If the
software detects a start flag and no finish flat, you will
receive this error.
Correction If the only problem is calibration values,
complete the calibration procedures in Chapter 5. One
other possibility is a A/D Power PCA U7 device failure.
Background The SYS/CTRL processor requests the
inguard module to run a self-test and report the results.
Failure For this error to occur, the module PCA did not
respond to the SYS/CTRL microprocessor request to run
a self-test. Neither "pass" nor "fail" was reported as if the
module PCA is dead or missing.
Correction Check that the module is properly plugged
into the backplane. Next, check that the power levels to
the module are the correct levels. Finally, check that the
power supply voltages generated by the power circuitry
on the module is generating the correct level of voltage.
The SYS/CTRL FPGA could be damaged for the
interface with the module PCA, or possibly the optics
opto-isolator devices A/D Power PCA U2 or U3 for the
serial data guard crossing are damaged. (Note that the
guard crossing serial data is similar to RS-232, except it
uses normal logic levels instead of RS-232 logic levels.)
Another possibility is the digital kernel on the module
PCA has failed. See "Troubleshooting the A/D Converter
PCA."
Background Each measurement function, V dc, V ac,
resistance, and frequency is subject to some sort of
signal conditioning and if this circuitry fails, it could
introduce an expectedly large offset error.
Failure This error suggests a problem in the signal
conditioning path, rather than the A/D converter itself.
Correction Check the components for each signal
conditioning method, depending the function that has failed.
You can, for example, apply different functions, i.e., V ac,
V dc, resistance or frequency, and note which function
measures incorrectly. Then look in the signal conditioning
components for the failure. Be sure A3W8 jumper is in place.