HP 8340B Manual page 148

17. Pull
the reference loop
—
M/N
loop casting out of the instrument.
18. Inspect
the bare contacts on the main instrument motherboard before
installing the new
reference
loop
—
M/N
loop
motherboard/casting assembly. Make sure they are clean and free of dirt, grit,
metal shavings, or any other type of foreign material. Inspect the
connectors
on the bottom of the
new motherboard/casting assembly, make
sure they are not
damaged
or bent. Install the new
motherboard/casting assembly so its
contacts are oriented the
same way
as those on the main
instrument motherboard.
On the top of the instrument, replace the
8
screws removed
In
step
14.
Refer to Figure B-23.
Reinstall the
A29, A30,
A31, and ASS assemblies, along with the 28 retaining
screws. Reconnect
all
cables. (Refer to Figure B-24 if
necessary.)
Reinstall the A19 capacitor Assembly
19.
Note that one end of the capacitor assembly has two tabs,
or flanges, with one screw hole in
each.
This end should
be lowered
into the instrument
first,
so the other end will
not
hit the side panel.
Press the P.C.
board fingers of the A19 assembly into the connector on the main instrument
motherboard.
20. Refer to
VIEW A and C. With
a
large pozidriv,
install the four
screws,
items
15
and
16.
Reinstall the
RF
deck
21.
Place the RF
deck
hinge on the standoffs it
attaches
to.
Make sure ribbon cable
W29
(shown
in
VIEW C)
runs under the
RF deck, between the two standoffs nearest the center of the instrument.
Make sure the ribbon cable is
not
pinched between the RF deck and the standoffs when screwing
the hinge in place (next step).
22.
Refer to
VIEW C. With
a
small pozidriv, install the
5 RF deck hinge screws, item 14. Plug the
W29
ribbon cable into the sockets on the
A20 and A16
assemblies.
23. Refer to
VIEW
D.
Reinstall the ribbon cable which
was
previously removed from the
A13
SYTM. Be
sure to orient the ribbon connector so that pin
1
of the connector and
pin
1
of the
A13J1
socket are
aligned.
The socket
is of
the variety normally used to hold integrated circuits, and pin 1 is
oriented
just as it
would be for an integrated
circuit.
24. Refer to
VIEW
B.
Swing the RF
deck
into its
closed position, being careful not
to pinch the A13
SYTM
ribbon cable and that the various disconnected semi-rigid cables (W14 and W16 shown
in
VIEW
B,
and W13 shown
in
VIEW C) are
not damaged
by
hitting microcircuit
assemblies.
25. Reconnect
all
cables disconnected in step
9.
Refer to VIEW C. To minimize signal leakage, lay
cables
W23 (A8-100 IN)
and
W24 (A8-MOD IN)
well
away from the A16 assembly.
26. Reverse steps
7
through
1
of this
procedure.
B-48
Reference Loop
-
M/N
Loop
Repair Procedures
HP 8340B/41B