Fluke 2680A Service Manual page 176

268XA
Service Manual
Error
Code
12 Module 1 open
thermocouple
detect failed.
13 Communication
parameters
corrupt.
14 Ethernet address
parameter
corrupt.
6-30
Table 6-9. Relating Selftest Errors to Device Problems (cont)
Error Code Suspect
Description Assembly
A3 A/D
Converter
PCA
Sys/Ctrl
PCA
Sys/Ctrl
PCA
Error Code
Discussion
Background The open thermocouple detect circuit
checks on the amount of a 19.2 kHz voltage developed
across a "thermocouple." Similar to the overload
detection, the self-test does not set any channel relays
and the detection circuit should detect the "open"
thermocouple.
Failure For this error to occur, the open-thermocouple
circuit has failed to detect the simulated open
thermocouple condition.
Correction Check the circuitry formed by the open
thermocouple detect circuit formed by A3U32 peak
detector and comparator and associated components
operates by applying a 19.2 kHz clock from A3U5 via
A3C82 into the measurement line. It checks on the
amount of 19.2 kHz voltage is developed. If the
developed voltage exceeds a certain level, this is
detected as an open thermocouple with a logic output at
A3U32-7. Similar to the overload detection, the self-test
does not set any channel relays and the detection circuit
should detect the "open" thermocouple. Also, check the
relays in the circuit path.
Background The SYS/CTRL stores the RS-232
communication parameters (baud rate) in the flash
memory and receives/transmits data through U8 to the
microprocessor, U6.
Failure For this error to occur, the RS-232 parameter is
no longer stored in flash.
Correction Check SYS/CTRL U20 is operating correctly
and has the correct level of voltages to it.
Background The SYS/CTRL U20 FLASH memory
device is divided into sections. One of these sections is
the memory for the Ethernet address. This is a unique
address assigned at the time of manufacturer.
Failure For this error to occur, the Ethernet address is
either missing or is corrupted and must be reloaded, or
the addressing is missing.
Correction Reloading the Ethernet address is a factory
procedure only. The only recourse is to order a new
SYS/CTRL U20 device programmed at the factory if the
Ethernet address is corrupted. Also, check SYS/CTRL
U20 for I/O and memory decoding. See
"Troubleshooting the Device" for more information.