Repair Procedure 01 - NCR PC4i Service Manual

Detail code:
01
02
04
These codes are logically nor"ed to present
final detail code.
Example: 03
or: 04

Repair Procedure 01

The detail code will give the location of a parity
failure (base or extended memory).
significant digit of the segment code to identify
which bank contains the defective RAM IC. This can be
done by using Figure 5-5. Refer also to Figures 5-3
and 5-4 shown earlier in this chapter.
Locate the segment number in the table and find the
data bit(s) that failed the RAM PATTERN TEST. The
junction of the row and column will intersect the IC
that is suspect. The locations of the ICs are found
on both MPBs, the Alternate and Early-Type MPB, all
other RAMs are located on the Memory Expander Card.
Memory bit IC locations on the MPB are shown in
Figure 5-8 and Figure 5-9» respectively.
test indicates a parity failure and the RAM
TEST passes, then suspect the parity IC within the
faulty segment.
LEVEL 1 DIAGNOSTICS ERROR RETURNS
Parity error interrupt
Base RAM parity error
Expansion RAM error
Parity error & interrupt from the
base RAM
Parity detected from expansion
RAM with no interrupt.
the
Use the most
If the
PATTERN
5-15