Fluke NetDAQ 2640A, Service Manual

Page: 186 / 260

NetDAQ
Service Manual
5-22
Table 5-10. Relating Selftest Errors to Instrument Problems (cont)
Error
Code Error Code
Description
Suspect
Assembly
Error Code
Discussion
7 Inguard not
responding. A3 A/D
Converter
PCA Background The A1U1 processor requests the inguard
A3 A/D Converter PCA to run a self-test and report the
results.
Failure For this error to occur, the A3 A/D Converter
PCA did not respond to the A1U1 microprocessor request
to run a self-test. Neither “pass” nor “fail” was reported as
if the A3 A/D Converter PCA is dead or missing.
Correction Check the ribbon-cable connection between
A1P10 and A3J10, or the power supply voltages to the A3
A/D Converter PCA. Refer to paragraph “A3 A/D
Converter PCA Troubleshooting.” The A1U1
microprocessor could be damaged for the interface with
the A3 A/D Converter PCA, or possibly the optics opto-
isolator devices A1U5 and A1U7 for the serial data guard
crossing. (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 A3A/D Converter PCA has failed.
See “Troubleshooting the A3 A/D Converter PCA.”
8 Inguard A/D failure. A3 A/D
Converter
PCA Background The A1U1 microprocessor requests the A/D
portion of the inguard A3 A/D Converter PCA to run a
self-test and report the results.
Failure For this error to occur, the A/D portion of the A3
A/D Converter PCA self-test report would be “fail.”
Correction The A/D portion of the A3 A/D Converter
PCA depends on accurate power supply levels (+50 mV).
In particular Vddr (+5.6V dc at A3U8-1), Vcc (+5.0V dc at
A3U8-3), Vdd (+5.2V dc at A3C31) and Vss (-5.2V dc at
A3C33).
See “Troubleshooting the A3 A/D Converter PCA” and
“Troubleshooting the Power Supply.”
9 Inguard zero
offsets test failed. A3 A/D
Converter
PCA Background Each measurement function, VDC, VAC,
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., vac, vdc, 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.