TH-25/45AT MODIFICATIONS
                   ========================

Part 2 of 4

Some of the above codes are:
K   USA
T   England
X   Australia
M   Other Areas

These components are found on the flexible circuit board under the display.
To get to them, take the radio apart.
(1)
Only 8 screws must be removed from the case to take the radio apart; these
are the 4 screws that hold the battery clip on, the 2 screws on the back half
of the case near the PTT switch, the screw on the back of the case under (and
in line with) the BNC connector, and the screw on the back half of the case
adjacent to the external speaker jack.
(2)
After removing these 8 screws, remove the front half of the case from the
back half. You may unconnect the blue plug from the touch tone circuitry on
the front half of the case to make further work on the radio more convenient,
but it is not necessary.
(3)
Place the radio back side down with the antenna away from you. Now, unsolder
the two grounding wires from the plate which covers much of the radio's
circuitry. These wires are easily seen near the top of the plate.
(4)
Next, remove the 7 screws that hold this plate on. 5 of the screws for this
plate are up on top and are quite obvious; the other 2 are at the bottom of
the plate, and may be hidden by your CTCSS unit. Remove the plate.
(5)
Remove the red plug with about 7 wires that connects just under the volume
and squelch switch.
(6)
Remove the screw that holds the PTT/LAMP/MONI switch assembly; this screw is
on the left side of the radio just under the PTT switch.
(7)
Remove the two screws that hold the top assembly to the back case of the
radio; these two screws are on either side of the orange flexible circuit
board coming from the top assembly and plugging into the back case of the
radio. You may need to use a screwdriver or stick to move the orange flexible
circuit board out of the way in order to see these final two screws.
(8)
Unplug the orange flexible circuit board from the back case. At this point,
the whole top assembly should come free quite easily. The BNC connector will
stay attached to the back case, and the top assembly will come up over it.
(9)
Unfold the flexible circuit board and unfold it so that the components are
accessible. One of the fold-out parts of the flexible board will look
something like this: (the component side is shown uppermost)

+................+
: R R R R D3 R R :
: 2 2 2 2   7 2 :The O's are very large solder pads.
: 5 4 3 2      1 :
:                :
: R  O      O R20: Not all components will be installed on your
: 2  O      O R19: circuit board.
: 6  O      O R18:
:    O      O R28:
:                : D3 & D4 are two diodes in a three terminal package.
:              R : The anodes of the diodes are in common.
:           D4 6 :
:        +.......+
:        :
:        :

The fold out board is actually square, but with only characters for graphics,
it couldn't be drawn that way.

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