HP Integral Personal Computer Service Manual page 115

,.. .... "7.
IC.,....,..
TNub .......
tIng
and R .... ir (Contln ..... )
Itep
***
ERROR - Keyboard time-
out error.
***
ERROR - incorrect key
count
***
ERROR - Hot all keys
responded with both
(down and up) keycod.s
2. Connect a known-good keyboard and cable
to
the computer. Run the complete keyboard
test. '
3. Remove the back panel and set up the com-
puter to troubleshoot the logic A peA (refer
to table 8-27). Thrn on the power and check
for
+
12 Vdc (11.4 to 12.6 Vdc) on pin 5 of
the logic A peA power connector (pin 1 has
a square designator).
I
Indiutecl ActIon
Repeat the test. If the error message
is still re-
ported, go to step 2.
Repeat the test. If the error message
is still re-
ported, replace the keyboard assembly.
Repeat the test. If the error message is still re-
ported, replace the keyboard assembly.
If the unit fails the test, reconnect the original
keyboard and cable, then
go
on to step 3.
If the unit passes the test, the problem
is in ei-
ther the keyboard cable or the keyboard PCA.
Reconnect the original keyboard assembly using
a known-good cable and repeat the test:
• If the test is now passed, replace the cable.
• If the test
is
failed, replace the keyboard peA.
If the voltage is not present or is out of range,
verify the power supply (refer to table 8-3).
If the voltage
is
correct, go on to step 4.
4. Connect a known-good keyboard connector If the unit passes the test, replace the keyboard-
assembly to the logic A PCA. Plug in the connector assembly.
keyboard and repeat the complete keyboard
If the
unit does not pass, go to step S.
test.
Ie Check that the frequency of the signal on
pin 22 of US8 on the logic A PCA is in the
range 45 to 75 Hz, nominally 60 Hz.
If the frequency
is
correct, go to step 6.
If the frequency is not correct, replace U59 on
the logic A PCA. If the frequency still is not cor-
rect, replace the logic A PCA.
L Check that the frequency of the signal on
If the frequency is correct, replace the Jogic A
pin 24 of US8 on the logic A peA
is in the PCA.
range 7.952 to 7.968 MHz. If the frequency
is
not correct, check the system
docks (refer to table 8-23).