Power Supply Fault - Data General NOVA 4/S Manual

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TROUBLESHOOTING WITH THE
SELF-TEST
Check out the computer with the self-test as follows:
1. Switch the power on.
2. If the self-test is completed (the entire message is
printed out) and any problems found during the
visual check are corrected, go to Chapter 7,
3. If the self-test is not successfully completed, follow
the procedure given below for the fault indicated. If
you replace a board and the self-test still indicates
the same fault, replace the original board before
continuing, unless otherwise indicated. Procedures for
replacing FRUs are given in Chapter 14.
NOTE Each time you replace an FRU, repeat
steps 1 through 3 until the self-test is
successfully completed.
Power Supply Fault
Go to Chapter 6, "Troubleshooting the Power Supplies."
Basic CPU Fault
1.
Replace the CPU board.
If the self-test still indicates a CPU fault with the
board, do the following:
a. Enter the virtual console (VC) by pressing the
RESET switch on the front console.
b. Read the contents of accumulators ACO, AC1, and
AC2 using the VC (see Chapter 2).
c. Replace the new CPU board with the original
CPU board and repeat steps a and b.
d. If the contents of the accumulators are NOT
identical in both cases, both CPU boards are
probably faulty. Try another CPU board, if you
e. If the contents of the accumulators are identical
in both cases, remove all the printed circuit
boards from the chassis except the power supply
board, the CPU board, and the memory board
which contains the first 16K physical addresses
(see "Memory Board Replacement,' Chapter 14 to
identify this board). If the self-test still indicates a
CPU fault, replace the power supply board.
If you have already replaced the CPU and power
supply boards, replace the bus terminators.
24
System Terminal Fault
1. Visually check out the terminal as follows, and then
repeat steps 1 through 3, "Troubleshooting with the
Self-Test," above.
a. Make sure the connectors on the device cable for
the system terminal are securely plugged into the
backpanel and the terminal.
b. Make sure the terminal is connected to the ac line
source, turned on, and on-line. Also make sure
the correct interface type and baud rate are
selected (see the CPU tailoring section of the
terminal but have NOT replaced the CPU board,
replace the CPU board. If the self-test still indicates
a system terminal fault with the new CPU board,
in step 2, "Basic CPU Fault," using both the new
accumulators are identical for both boards, continue
to step 3; otherwise, try another CPU board, if you
See if the system terminal works in local mode. If it
does, replace the device cable; otherwise,
troubleshoot the system terminal (see the
documentation for the appropriate terminal).
already done steps 1 through 3, replace the power
supply board.
1. Remove the memory board which contains the first
16K physical memory addresses and check the board
select jumpers (see "Memory Board Replacement,"
. If the correct board select jumpers are inserted,
replace the memory board.
If the self-test still indicates a memory fault with the
new memory board, check the contents of the
accumulators as described in step 2, "Basic CPU
Fault," using both the new and original memory
boards. If the contents of the accumulators are
identical for both boards, replace the CPU board and
continue to step 4; otherwise, try another memory
board, if you have one.
If you have already replaced the CPU board and the
self-test still indicates a memory fault, check the
contents of the accumulators as decribed in step 2,
"Basic CPU Fault," using both the new and original
CPU boards. If the contents of the accumulators are
identical for both boards, continue to step 5;
otherwise, try another CPU board, if you have one.
In a 16-slot chassis if you have already done steps 1
through 4, see if the memory board will work in any
available memory slot. If it does, move the bus
terminators, if required.
If you have already done steps 1 through 5, first
replace the bus terminators. If this does not correct
the problem, replace the power supply.