June, 2000
6880905Z99-O
2-5
GTX LTR/Privacy Plus 800 MHz Mobile Service Manual
Basic Maintenance
Repair Procedures and Techniques
Positioning New Transistor
1.
Place a small spot of flux on each of the six
main-board pads to which the flanges of tran-
sistor are to be soldered.
2.
Insert the narrow-diameter side of a spacer,
Motorola Part Number 4380545K01, into each
of the two transistor mounting holes in main
board.
3.
Ensure that new transistor is correct replace-
ment type by verifying that M25C17 is printed
on transistor face.
NOTE
Collector flange of transistor is the one
with its corner cut off.
4.
Position new transistor onto transceiver board
with
collector
flange
oriented
towards
antenna connector. Ensure that transistor is
sitting snug on main board with all six flanges
flat on their corresponding main-board pads.
5.
Lower arm of Distaco clamp on transistor
assembly tool. Then lock clamp with its lever
to clamp transistor in place on main board.
Soldering Transistor
1.
Place a small spot of flux on each of the six
transistor flanges.
2.
Solder each transistor flange to transceiver
board as follows:
2A. Set soldering iron temperature to approxi-
mately 400 degrees Centigrade.
2B.
Melt a small mound of solder onto flat face
of soldering iron.
CAUTION
In next step, to avoid damage to transis-
tor and capacitors, ensure that each sol-
dering operation takes no more than
three to four seconds to accomplish.
3.
Press face of soldering iron firmly to flange for
no more than three to four seconds.
4.
Inspect transistor flange carefully to ensure it
is soldered securely, and that it is not shorted
to any of the other flanges or to the transistor
heat sink.
Installing Flange Capacitors C6567 and C6568.
NOTE
C a p a c i t o r s C 6 5 6 7 a n d C 6 5 6 8 g e t
mounted flat on transistor collector and
ground flanges with non-solderable edge
flush against transistor body. Each capac-
itor is attached by soldering its outside
solderable edge to one of the transistor
ground flanges and its inside solderable
edge to transistor collector flange. There
must be a gap of approximately 2 milli-
meters between the two capacitors (i.e.,
room to insert a chisel style solder iron
tip) to ensure that good solder joints can
be made between capacitor leads and
collector flange of transistor.
1.
Ensure that both capacitors C6567 and C6568
are correct replacement type by verifying that
Motorola Part Number is 2113742B25, value is
18pF, and marking is Gl.
CAUTION
In next two steps, to avoid damage to
transistor and capacitors, ensure that
soldering operations take no more than
three to four seconds to accomplish.
2.
Solder outside solderable edge of each capaci-
tor to one transistor ground flange, being cer-
tain that each capacitor is flat on transistor
flange with non-solderable edge flush against
transistor body.
3.
Place a small drop of flux on transistor collec-
tor flange between capacitors. Place chisel
style solder iron tip between capacitors and
onto collector flange of transistor. Feed in
some high temperature solder (SN96PB04) so
that inside solderable edges of both capacitors
are soldered securely to collector flange of
transistor.
4.
Examine soldered capacitors. Ensure that they
are reasonably flush against transistor body
and are not shorting transistor collector flange
to transistor heat sink.
5.
Examine surrounding components to ensure
that none of them have been damaged or dis-
placed.
Reassembly of Radio
1.
Examine face of transistor heat sink. Ensure
that it is free from burrs and flux, which could
prevent a good thermal contact to radio chas-
sis.