Motorola 880 Service Manual page 63

Table 7: DCS Receiver Troubleshooting and Repair Chart
RX Symptom
2. Receive audio
is weak and/or
distorted.
Table 8: DCS Transmitter Troubleshooting and Repair Chart
TX Symptom
1. Transmit
audio is weak,
(usually indi-
cated by called
parties
complaining of
difficulty in
hearing voice
from portable
phone).
12/9/97
Probable Cause
c) Antenna assembly is
defective.
d) Logic/RF Board Assembly
defective.
Probable Cause
a) Microphone connections to
Keypad/Display board
defective.
b) Microphone defective.
c) Logic/RF Board Assembly
defective.
68P09403A50
Verification and Remedy
1. Check to make sure antenna pin is properly
connected to the
Assembly. If OK, substitute a known good
antenna assembly.
2. If antenna assembly is not at fault, re-install
original antenna assembly and proceed
to d.
1. Replace Logic/RF Board Assembly.
2. If substitute Logic/RF Board Assembly
works, the original is faulty and should be
examined for improper solder and/or
connections. Likely fail components: J803,
U701, U703, U500, and U900.
Verification and Remedy
1. Gain access to
described in "Disassembly" on page 29.
2. Check connections (including checking for
polarity) and if OK, proceed to b.
1. Gain access to microphone (located on
keypad membrane).
2. Disconnect and substitute a known good
Microphone.
3. Place a call and verify improvement in
portable transmit signal as heard by called
party. If good, re-assemble portable with
new Microphone.
4. If Microphone is not at fault, re-install orig-
inal Microphone and proceed to c.
1. Replace Logic/RF Board Assembly.
2. If Logic/RF Board Assembly is at fault,
examine it for improper solder and connec-
tions.
Troubleshooting
Logic/RF Board
the Microphone as
55