TROUBLESHOOTING AND REPAIR
DIGITAL CONTROLLER
Repairing Calibration/Compensation Memory Checksum Errors 6B-24.
Special Function 907 attempts to repair all invalid data segments reported by the
calibration/compensation memory status command. Special Function 907 can be
used to repair an error in an individual data segment, or to initialize a new EEPROM
or battery-backed RAM IC following the replacement of a defective part.
NOTE
The rear panel CAL\ COMP switch must be set to the "1" position before
performing Special Function 907.
If the checksums in both ICs are valid for a given data segment, no transfers are
performed. However, if one checksum is valid and the other is invalid, the message
"—Sto—" is displayed, and the good data is copied over the bad. If both checksums are
bad, no transfers can be performed. Each redundant data segment pair is checked and
updated individually.
After all transfers are complete, the checksums are verified again and any remaining
failures are reported.
It also resolves the situation where a segment in EEPROM and in the battery backed
RAM both have valid checksums but contain different data. The EEPROM data
segment is always copied to battery backed RAM in this situation.
Calibration/Compensation Memory Origin Status 6B-25.
The data in the calibration/compensation memory can be generated by:
• The Fluke factory
• Through Module Exchange (MEC)
• The user (performing the calibration or compensation procedures).
The calibration/compensation data origin code specifies how the particular data
segment was generated. A segment's data origin may have a bearing on future actions
so it is desirable to know how each was generated. Refer to Appendix H,
"Compensation Procedures".
Special Function 05 displays the data origin codes. If all data segments were generated
by the Fluke factory, the origin code 00 is displayed. If any of the data segments were
generated any other way, the corresponding status code is displayed. If there are more
than four codes, the list can be scrolled by pressing the key. Refer to Appendix
F for a complete list of origin codes.
FRONT PANEL CIRCUIT DESCRIPTION 6B-26.
The front panel section is mounted in a sheet metal housing and consists of the A1
Display PCA, a switch circuit board, elastomeric switches, and the edit knob. The
front panel section also includes the display lens, the AM INPUT connector, the
FM/øM INPUT connector, and the PULSE INPUT connector.
All front panel control keys, except the POWER ON/OFF button, consist of an
elastomeric membrane sandwiched between the switch circuit board and the front
panel sheet metal housing. The switch circuit board consists of an 8-by-8 matrix of
open switch contact pads. When a key is pressed, a conductive pad on the back of the
elastomeric membrane connects a set of contact pads. The software senses what row
and column of the matrix are connected when a key is pressed. The two opto-interrupter
ICs for the edit knob are the only active components mounted on the switch PCA.
6B-9
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