TH-K4AT/K4E
3
DISASSEMBLY FOR REPAIR
Soldering the antenna terminal
1. With the shield cover removed from the antenna terminal
section, install two screws on the PC board and bring the
PC board into contact with the chassis (
z
).
2. Solder the antenna terminal with a soldering iron (
x
).
3. Remove the two screws installed in step 1 above, and install
the two screws again on the PC board together with the
shield cover (
c
).
Replacing the final FET (Q12)
1. Remove the two screws holding the shield cover of the
final FET section (
z
).
2. Remove solder from the shield cover completely with a
solder absorber.
3. Remove the shield cover (
x
).
z
x
c
z
x
4. Apply the tips of soldering irons to all the four pins of the final
FET at the same time (
c
), heat them sufficiently, and remove
the final FET (
v
). (Two persons should be required to do this.)
5. Remove all PC boards from the chassis.
6. Confirm that there is no space between the radiation plate
installed on the foil side of the TX-RX PC board (TX-RX unit
A/3) and the PC board (
b
). If there is any space between
the radiation plate and PC board, eliminate it by applying
the tip of the soldering iron to the radiation plate.
7. Apply the tip of the soldering iron to the installation side of the
radiation plate of the TX-RX PC board, put a little amount of
solder to the radiation plate that is seen through a square hole
in the final FET installation section and melt the solder (
n
).
8. When the solder in step 7 is melted, place the final FET on
the PC board by aligning it with the silk of the final FET
installation section of the PC board (
m
).
9. Release the soldering iron and confirm that the final FET
and radiation plate have been soldered.
10. Solder the four pins of the final FET with the soldering iron.
11. Install all the PC boards.
12. Reinstall the shield cover removed in step 3 above in its
original position and install two screws.
13. Solder the shield cover to the PC board.
14. Install the chassis on the case assembly and assemble them.
15. Readjust transmission power.
Note:
Since the FET is sensitive to static electricity, always
wear a grounding band. Use a highly insulated ceramic
heater solder iron.
Radiation plate
TX-RX PC board
b
c
v
m
n
This illustration is
M2 type.
