Service manual

If a processor’s yellow LED is OFF and the red LEDs show an error code
in the range 1–37, the power-up self-test failed and the processor board is
bad. On the self-test console display, the processor shows a minus sign (–)
on the STF line.
After the power-up tests, each processor runs the CPU/memory interaction
tests. If a test fails, the processor shows a minus sign (–) on the ETF line of
the self-test console display. The LED error codes are numbered from 50 to
62, which is the failing test number (1 through 13) plus 49, the number of
tests in RBD 0. For example, assume that a processor fails self-test (yellow
LED is OFF) and shows the following pattern in the error LEDs:
TOP
(MSB) off 1
on 0 = 5
off 1
on 0
off 1 = 6
off 1
on 0
BOTTOM
The failing test number decodes to 101 0110 (binary-coded decimal 56),
which corresponds to the seventh CPU/memory interaction test ((56–49 =
7).) If you then run RBD 1 with the /TR and /HE qualifiers, the last test
number you see displayed is T0007.
Each processor, after testing with the first memory, runs the CPU/memory
interaction tests on every other good memory module. (However, only CPU/
memory interaction test T0003 is run.) If a failure occurs, the memory
module is probably bad, although the processor’s yellow light is OFF and
the memory module’s yellow light is ON. If several processors fail on the
same memory, the memory is certainly bad. Try using SET MEMORY to
configure the bad module out of the interleave set. For error codes higher
than 66, consult Table 4–2 to determine the failing memory.
The last series is the DWMBB tests. If one fails, the red LEDs contain an
error code, although the processor’s yellow self-test LED is ON (because the
CPU itself has passed). The failing test numbers are listed in Table 7–5.
Note that only the boot processor performs the DWMBB tests.
<REFERENCE>(XRP) Scalar Processor 4–23