HP Integral Personal Computer Service Manual page 99

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8-3.
Power-Supply Verification
If the computer does not tum on, use the procedure of table 8-2 to eliminate the possible causes. If
the power supply appears to be at fault, use this procedure to verify its operation.
_RMING
Life-threatening voltages are present in the power suppl}' when the ac power cord is plugged in. The
primary
circuitry is live even whtn tht power switch is turned off. Use extreme caution when you are
servicing the power supply.
All voltage measurements made on the primary side of the power-supply circuit must be made with
an isolated or battery-powered test instrument. If you fail to observe this precaution, the equipment
may be damaged, and you may be exposed to shock hazard, since the primary circuit is not isolated
from the ac power line.
Itep
1. Tum the power switch off. Check that the
power supply voltage-select switch is set at
the proper voltage and that the fuse is good.
Check that line voltage is present at the
power outlet and that the power cord is in-
stalled correctly.
2. If any interfaces or peripherals are con-
nected to the computer, disconnect them.
Tum on the power to verify that the turn-on
problem was not caused by the external
devices.
3. Turn off the power. Remove the back case
from the computer (refer to section 6.5), re-
move the logic A peA shield, and lower the
logic PCA mounting panel (refer to section
6.8).
4. Disconnect the power-cable harness from
the logic A peA, the logic B PCA, and the
disc drive.
I
Respon . .
If the unit does not turn on, go to step 3.
If the unit does tum on, reconnect the interfaces
and peripherals one at a time until the unit does
not turn on. Repair any interface or peripheral
that prevents the computer from turning on (re-
fer to the appropriate service manual).
CAUTION
Be sure to plug the power-supply test tool into the logic B connector on the power-cable harness
only. If you plug the tool into the logic A connector, serious damage to the unit may result.
Make sure that the power supply test tool does not contact the metal chassis. A short circuit may
result in damage to the test tool and power supply.