HP Integral Personal Computer Service Manual page 120

,..... .... Diu Drive TrouItIeahooting and R .... ir
Use the following procedure to troubleshoo"t and repair a disc drive problem.
In each of these steps,
always turn off the power before you connect or disconnect
II
cable or replace a component.
Itep
1. For any disc failure, insert a new, formatted
floppy disc
in the drive and repeat the test.
2.
Remove the back panel &om the computer.
Check that the switch on the back of the
disc drive is in the
down
position (see
figure
6-23b).
3. Prepare
the
computer to troubleshoot
the
logic B peA (refer to table 8-27). Repeat the
test. Take the indicated action for the error
message displayed.
***
ERROR -
Disc
CRe
error.
***
ERROR -
Disc interrupt
er r or .
***
ERROR -
Disc record not
found. "
***
ERROR -
Disc tiMe-out
error.
***
ERROR -
Disc
(W/R)
data
Mismatch.
***
ERROR - Lost data bit
during read sector comMand.
***
ERROR -
Lost data bit
during write sector COMmand.
***
No disc detected in unit.
***
The disc in the unit is
worn. Please replace with
a new formatted disc.
I
Indicated Action
If the test is failed with the new disc, go on to
step 2.
If the switch
is
not in the down pOSition, correct
it and repeat the test. Otherwise, go on to
step 3.
(Cyclic Redundancy Check error.) Go to step 4.
Troubleshoot the interrupt circuitry (refer to ta-
ble
8-24).
Go to step 4.
Go to step 4.
Go to step 4.
Go to step 4.
Go to step 4.
Make sure a formatted disc is properly installed
in the drive and repeat the test. If the error mes-
sage is repeated, check the DSKCHG signal at
pin 3 of U20 on the logic B PCA .
• Pin 3 should be high (4.75 to S.25 Vdc). If
not, replace the disc drive.
• If pin
3
of U20 is high, check pin 4 of
U20.
Pin 4 should be low (0.0 to 0.3 Vdc). If not,
replace U20. If pin 3 of U20 is high and pin 4
is low (but the error message still appears),
replace the logic B PCA.
Repeat the test with a new blank, formatted
disc.