Motorola 880, Service Manual

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Troubleshooting
2. Receive audio
is weak and/or
distorted. c) Antenna assembly is
defective. 1. Check to make sure antenna pin is properly
connected to the Logic/RF Board
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.
d) Logic/RF Board Assembly
defective. 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.
Table 8: DCS Transmitter Troubleshooting and Repair Chart
TX Symptom Probable Cause Verification and Remedy
1. Transmit
audio is weak,
(usually indi-
cated by called
parties
complaining of
difficulty in
hearing voice
from portable
phone). a) Microphone connections to
Keypad/Display board
defective. 1. Gain access to the Microphone as
described in “Disassembly” on page 29.
2. Check connections (including checking for
polarity) and if OK, proceed to b.
b) Microphone defective. 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.
c) Logic/RF Board Assembly
defective. 1. Replace Logic/RF Board Assembly.
2. If Logic/RF Board Assembly is at fault,
examine it for improper solder and connec-
tions.
Table 7: DCS Receiver Troubleshooting and Repair Chart
RX Symptom Probable Cause Verification and Remedy