Operator`s manual

41. Removal and Replacement of Audio
and Control Chassis A27
(fig. 32)
a. Removal.
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Remove modules A21 through A25
as described in TM 11-5820-398-
20, paragraph 10a.
Remove relay K3.
Unsolder and remove 11.5-mc fil-
ter FL3.
Unsolder and remove receiver dis-
criminator Z1.
Tag and unsolder all wiring to relay
socket XK3 and audio and control
chassis A27 terminal strip.
Rem o v e the wiring through the
grommet at the lower left corner of
the audio and control chassis.
Using a hacksaw, cut off one end of
the metal dowel protruding from
the audio and control chassis A27
hinge.
Grasp the other end of the metal
dowel with pliers and remove the
metal dowel from the hinge.
Release the three audio and control
chassis captive screws and separ-
ate audio and control chassis A27
from the RT-505/PRC-25.
b. Replacement.
(1)
(2)
(3)
(4)
Align the hinge on audio and control
chassis A27 with the hinge on RT-
505/PRC-25.
Insert a new metal dowel and push
downward until the dowel extends
through the entire hinge.
Crimp the metal dowel at both ends.
Insert the wiring through the grom-
met at the lower left corner of the
audio and control chassis A27 (fig.
33) and solder all the electrical
leads to XK3 and to the audio and
(5)
(6)
(7)
(8)
(9)
control chassis A27 terminal strip.
Replace 11.5-mc filter FL3 and
solder the connections.
Replace receiver discriminator Z1
and solder the connections.
Replace relay K3 into socket XK3.
Replace modules A21 through A25
as described in TM 11-5820-398-
20, paragraph 10b.
Secure audio and control chassis
A27 with the three audio and con-
trol chassis captive screws.
42. Removal and Replacement of Synthesizer
Mother Board A26
(fig. 34)
a. Removal.
(1)
(2)
(3)
(4)
(5)
Remove modules A10 through A20
as described in TM 11-5820-398-
20, paragraph 10c.
Remove the 10 module nuts and
bushings.
Loosen the four mother board cap-
tive fasteners.
Gently pull the mother board away
from the chassis.
Tag and unsolder all wiring to the
mother board.
b. Replacement.
(1)
(2)
(3)
(4)
(5)
Solder all electrical leads to the
mother board.
Align the four mother board captive
fasteners with the holes in the
chassis.
Secure the mother board captive
fasteners.
Replace and tighten the 10 module
nuts and bushings.
Replace modules AlO through A20
as described in TM 11-5820-398-
20, paragraph 10d.