Error Codes; Repair Procedures - NCR PC4i Service Manual

LEVEL 1 DIAGNOSTICS ERROR RETURNS
This section describes the error
NCR Personal Computer SERVICE DIAGNOSTICS program.
The reports from the diagnostics are in coded form.
This reduces the large overhead of program code
required for text.
accompanying text.
RELATIONSHIP BETWEEN MAJOR CODES, DETAIL
CODES AND REPAIR PROCEDURES
Error codes are broken down into MAJOR and DETAIL
codes. In addition, ADDR(ess), EXP(ected) DATA, and
OBS(erved) DATA information is also displayed where
appropriate.
description of the type of test being performed when
an error was encountered. This code is a BCD value
that is displayed on the CRT and also presented to
the printer data port. Each MAJOR code may have
several DETAIL codes associated with it.
codes are specific descriptions of the error and are
displayed as hex values on the CRT only. Data that is
to be returned from a particular register or memory
device is displayed in the EXP DATA and OBS DATA
fields. If the OBS(erved) DATA does not match the
EXP(ected) DATA then an error has been detected. The
ADDR(ess) field is for memory related failures.
After every MAJOR CODE the "Repair Procedure" that is
recommended to troubleshoot the faulty condition is
presented. Additional "Repair Procedures"
specific DEVICE codes. On the Main Processor Board
(MPB), each semiconductor component is identified by
a "U" number.
components on the MPB by the appropriate "U" number.
Figure 5-6 shows the location of components on the
MPB by "U" numbers.
performing repairs includes: Multimeter,
Logic Probe.
5-8

ERROR CODES

Codes are exemplified
The MAJOR codes are,
The repair
Equipment recommended
reports from the
in general,
The DETAIL
may follow
proc e d u r e s
in the
a
s p ec i f y
for
Digital