45
Service Manual
5-4
clean to ensure a strong connection. An oxidized pca pad causes the solder to wick up
the component lead, leaving little solder on the pad itself.
5-3. Error Codes
At reset, the Fluke 45 software attempts power-up self-tests and initialization of ROM,
RAM, Display, EEROM, and measurement hardware. Self-test failures are reported on
the display with "error" in the secondary display and an error code (1-9) in the primary
display.
Several of these error codes might never be displayed. Certainly, errors 4 and 5, which
signify a faulty or dead display, could not be reported in the normal (displayed) manner.
Other errors might not appear on the display.
The keyboard scan lines (A1U6, SWR1-5), which are also used as status indicators, can
be checked as a last resort for accessing error information. The software sets SWR1
(A1U6-21) low to indicate that the basic operation of the processor, ROM, and ROM
decode circuitry is intact. SWR2 (A1U6-22) is set low if the ROM check passes. SWR3
(A1U6-23) is set low if the external RAM (A1U10) check passes, and SWR4 (A1U6-24)
is set low if the internal RAM (A1U6) check passes. Then, if the display self-check
passes, SWR5 (A1U6-25) is set low to indicate that the display is operational.
Table 5-1 describes the error codes.
Note
Each error code is displayed for 2 seconds. Any button press during this
period aborts the error display
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