Vii. Board Replacement - Motorola Spectra Service Manual

WARNING
When wearing a conductive wrist strap, be care-
ful near sources of high voltages. By grounding
you thoroughly, the wrist strap also increases the
danger of lethal shock from accidental contact
with such a source.
2. Whenever possible, avoid touching any electrically
conductive parts of the circuit module with your
hands.
3. Be sure that all electrically powered test equipment
is grounded. Attach the ground lead from the test
equipment to the circuit module before connecting
the test probe. Similarly, disconnect the test probe
before removing the ground lead.
4. When you remove a circuit module from the system,
lay it on a sheet of aluminum foil or other conductive
surface connected to ground through 100,000 ohms
of resistance.
WARNING
If the aluminum foil is connected directly to
ground, you may get a shock if you touch it and
another electrical circuit at the same time.
5. Replacement modules shipped separately from the
factory will be packaged in a conductive material.
Any modules being transported from one area to
another should be wrapped in a similar material
(aluminum foil may be used). NEVER USE NON-
CONDUCTIVE MATERIAL for packaging these
modules.

VII. BOARD REPLACEMENT

This section details the procedures necessary to
remove and replace the printed circuit boards in the
Spectra radio. After troubleshooting and determining
which board needs to be replaced, disconnect the test
equipment, the antenna cable, and unhook the dc
power.
Disconnect all dc power to the radio before
removing any boards from the radio. Failure to
remove power can result in unit damage caused
by transients or accidental shorts.
CAUTION
Locate the exploded view drawing of the radio in the
back of this section. Keep it handy for reference when
disassembling and reassembling the radio.
When installing a new circuit board, all mounting
screws should be started before any are torqued. This
helps assure proper board alignment with the chassis.
After installing a new board, refer to Table 16 and
perform the alignment procedures indicated for the
replaced board.
IMPORTANT
After performing alignment procedures, always exit
the "SERVICE" menu entirely (to the MAIN MENU) to
save all changes properly. Failure to do so can result
in an "FL 01/82" failure (see Table 11).
A. Control Head Board (Spectra)
1. Unplug the microphone and remove the two front
panel screws. Disconnect the control cable on
remote models. Grasp the front panel firmly and
carefully unplug the assembled control head from
the radio or remote control head back housing.
2. Lay the control head face down on your work
surface.
3. Remove seven screws (use a Torx T10 driver) or
four screws for rotary models. Rotary models have,
in addition to the screws, four snap features as
shown in Figure 15. Carefully separate the printed
circuit board, internal spacer, and elastomer keypad
assembly from the front panel. On rotary models,
care must be taken not to damage the flex circuity
when separating the printed circuit board from the
front housing. Do not disturb the buttons in the front
panel. On rotary models, the flex circuit must also
be unplugged. If you have a rotary model, desolder
the XMIT and Busy LED before removing the elas-
tomer keypad. Remove the elastomer keypad from
the printed circuit board.
4. Remove keypad from the PC board.
Before you unsnap the PC board, notice that the
board slips under a hook on the right and snaps on
the left. This will facilitate assembly.
NOTE
41