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We recommend the procedures given below to remove a large flat-package IC
device. The principle is the same for each procedure: the electrodes
(pins, leads or other shapes) of the device are desoldered, and the
device is removed while the solder is still in a liquid state.
(1) Use two soldering irons to desolder the electrodes of the device.
Move the soldering irons to apply heat equally to the electrodes and
to remove the device while the solder is still in a liquid state.
(2) Do the procedure (1) between two persons if the device is extremely
large. This procedure uses a total of four soldering irons.
(3) Use a hot air blow type desoldering station. Refer to the
manufacturer’s instructions for the procedure.
F. Power Semiconductor Devices
The power semiconductor devices are A4D401 thru A4D405 and A4IC401 on the
A4 card. Obey the instructions given below to replace one of these
devices:
(1) Removal of Device
(a) Remove the screw, flat washer and nut that attach the device to
be replaced.
(b) Desolder the leads of the device and remove the device.
(c) Remove the used silicone heat-sink compound from the deviceremoved
area of the heat sink assembly with a low-lint cloth.
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COMPONENT MAINTENANCE MANUAL
PART NUMBER RD-AA5002 SERIES
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(2) Installation of Replacement Device
(a) Bend the leads of the replacement device. Refer to the removed
device for the bending position and shape.
(b) Apply a layer of silicone heat-sink compound on the device
surface that comes in contact with the heat sink assembly.
(c) Attach the replacement device on the heat sink assembly with the
screw, flat washer and nut.
(d) Solder the leads of the replacement device, then cut off the
lead ends.
NOTE: The device leads are soldered after the device is
installed to prevent tensions and stresses on the leads
and soldered connections.
G. Coax Contacts
The coax contact is not a part of the connectors given below. If the
REPLACEMENT column shows "coax cable assembly", the coax contact or
contacts must be replaced as a coax cable assembly.
LOCATION CONNECTOR(S) COAX CONTACT REPLACEMENT
A2 Card A2CN201 Right-angle type Coax contact
A3 Card A3CN301 Right-angle type Coax contact
A5 Card A5CN6 thru A5CN18 Straight Type Coax cable assembly
J1 J1 middle plug Straight Type Coax cable assembly
(1) Replacement of Right-Angle Coax Contacts
Obey the instructions given below to replace the right-angle coax
contact(s):
(a) Desolder and remove the connector together with the coax
contact(s).
(b) Remove the coax contact(s) from the connector. Use the contact
removal tool for right-angle coax contacts.
(c) Assemble the connector and replacement coax contact(s) or the
replacement connector and coax contact(s) together.
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COMPONENT MAINTENANCE MANUAL
PART NUMBER RD-AA5002 SERIES
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(d) Attach the assembled connector to the A2 or A3 card.
(e) Solder the pins of the connector and coax contact(s).
(2) Replacement of Coax Cable Assembly
Obey the instructions given below to replace the coax cable
assembly:
(a) Remove the coax contacts from the connectors to remove the coax
cable assembly. Use the contact removal tool for straight
contacts. Different tools are necessary for those on the A5
card and for those on the J1 connector.
(b) If the coax cable assembly is soldered to the coax holder at one
end, desolder the soldered end and remove the coax cable
assembly.
(c) Put the coax contacts of the replacement coax cable assembly
into the related connector positions. No tools are necessary to
put the contact into the position.
(d) If the coax cable assembly has a soldering end, solder this end
to the related coax holder.
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Panasonic Avionics Corporation
COMPONENT MAINTENANCE MANUAL
PART NUMBER RD-AA5002 SERIES
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ASSEMBLY
1. General
A. This section gives instructions to install the primary assemblies into
Video Modulator Unit (VMU).
B. Do the disassembly work in a fully de-energized condition with the test
harness removed from the J1 connector of the VMU.
C. Electrostatic discharges from your hands or tools can cause permanent
damage to most of the semiconductor devices on the printed circuit card
assemblies. Obey the general precautions given below to prevent such
damage:
· Do the disassembly and assembly work on a grounded conductive surface.
· Put on a conductive wrist-strap that is grounded.
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COMPONENT MAINTENANCE MANUAL Video Modulator Unit (VMU)(87)
