Receiver Troubleshooting - Motorola MTH500 Service Manual

Troubleshooting

Receiver Troubleshooting

Check second LO .
-16dBm<Power<-10dBm
Freq.=219.3MHz
Re pa ir if necessary
(See Synth. Troubleshooting)
Check BaseBand
WPIC (U503) TP500/TP501.
Replace if necessary.
Return to first
test.
TetraCom Commands
Mode):
>Freq. RX 390.0125
>Mode RXTDM/Mode
>LIMITER ON
>BER
Rout WPIC BaseBand
to test point s:
>WPI C 2 0 7 2 NOW
Activating control lines at
continuos mode:
WPI C 3 9 1 b NOW
3 - 22
No
Ye s
Wa s that the
problem ?
No
Output at
No
(TD M
RSSI
signal
Check Front Gain, using
a R F probe on C536,
Frequency 109.65MHz
Is the
Ye s
gain below
4dB?
Run RX_BER -112dBm &
UL TIMA TE_BER
Passed?
No
Ye s
OK
Check with all power
Input s/Output s o f Ant. SW .,
Front Filter (Fl500), LN A
(U500), Second Filter (Fl501),
Mixer (U504), Xt al Filter
(Fl502). Replace if necessary .
Check Front Gain again.
Is the
No
Gain still below
4db?
Ye s
Check 2.775V suppl y t o
LN A & Mixer and check
control lones (Q504, Q500).
Rep air if necessary .
Check Front Gain again.
Is the
Gain still below
4db?
Ye s
Check Main Synth. Power
level (>-5dBm) and frequency .
F F +109.65MHz).
main = rx
Rep ai r i f necessary .
(See Synth. Troubleshooting)
68P02963C70-O