Motorola ASTRO MT 1500, Service Manual, Page: 278 / 817

August 16, 2007 6816985H01-B
6.5-18 900 MHz Troubleshooting Charts: 900 MHz Frequency Generation Unit Troubleshooting Chart
6.5.19900 MHz Frequency Generation Unit Troubleshooting Chart
FGU NoLO
Injection/TX
Unlock
For RX check C261,
L212, L230, R222,
for continuity.
For TX check C266,
C277, C278, L210,
Q216, R289 and R292
Change U250
Replace Y200
and/or C243
Check
U202 circuitry
Replace
U201
Fix/replace
U202
Do a continuity
check and refer to
DC switch chart
Replace
U201
Do a continuity
check and refer to
DC switch chart
Replace
suspected
component
Is Vdc at
D212(RX VCO)
D211(Tx VCO)
0.4<Vdc<12?
Is Vdc at
R262,
High for Tx,
Low for Rx mode
No
Take a continuity
check of traces
to U201
No
No
No
No
No
No
No
No
No No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Is Vdc
at C217 3V?
and C201
5V?
Is there
a voltage reading
at R201, R202, R214,
R215 directed
to U201?
Is Vdc
at Y200 pin 4
3V?
Do you
see 16.8MHz at
pin 3 of Y200 and C243
connection to Xtal
K9 pin of
U201?
Do
you see
16.8MHz at
C293?
Do
you see
~11.5 Vdc at pin 2
of D202?
Replace
U201
Yes
Is
3Vdc at
pin 4 of
D201?
Check components
D201, D202, C202,
C203, C204,
and C205
For TX only pin 3 of Q216 (TX)