Motorola 880, Руководство по обслуживанию

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54 68P09403A50 12/9/97
Dual Band 880/890 (DCS/GSM)
Table 7: DCS Receiver Troubleshooting and Repair Chart
RX Symptom Probable Cause Verification and Remedy
1. Portable tele-
phone exhibits
poor reception
and/or erratic
operation
(such as calls
frequently
dropping,
weak and/or
distorted
audio, etc.). a) Antenna assembly is
defective. 1. Check to make sure that the antenna pins
are properly connected to the Logic/RF
assembly. If OK, substitute a known good
antenna assembly.
2. If the fault is still present, proceed to b.
b) Defective or mis-phased
RF/Audio-Logic Board.
1. Check for appropriate frequencies and
power level gains/losses in the RX path.
2. Replace malfunctioning components if
listed on parts list. Likely fail components
are: FL401, FL462, FL480, Q205, Q402,
Q430, Q460, Q480, and U402.
3. If parts replacement doesn’t correct the
fault, replace transceiver.
c) Defective keypad board.
(i.e. OK key won’t work)
1. Substitute keypad and logic board with a
known good keypad and logic board.
2. If known good board works, place the
keypad from the defective unit onto it and
attempt to function.
3. If unit functions properly, replace the mylar
barrier on the defective unit and then
attempt to function defective unit with orig-
inal keypad.
4. If fault persists, replace the logic board.
2. Receive audio
is weak and/or
distorted. a) Connections to/from
Keypad/Display circuit
board defective. 1. Gain access to Keypad/Display board as
described in “Disassembly” on page 29.
2. Check connection from earpiece to Keypad/
Display circuit board. Make sure to check
polarity and solderability. If connection is
not at fault, proceed to b.
3. If Keypad/Display board is faulty, examine it
for improper solder and/or connections.
Likely fail components: J500.
b) Earpiece speaker defec-
tive. 1. Gain access to earpiece speaker as
described in “Disassembly” on page 29.
2. Substitute a known good earpiece speaker.
Place a call and verify improvement in
earpiece audio. If good, re-assemble
portable with new earpiece speaker.
3. If earpiece speaker not at fault, re-install
original earpiece speaker and proceed to c.