Motorola ASTRO Digital Spectra Plus Detailed Service Manual page 221

Troubleshooting Charts
6881076C25-E
Bad SINAD.
Bad 20Db Quieting.
No Recovered Audio.
Note: Inject Modulated On
Carrier Frequency
Signal As Required.
Inject 1 st IF
into Johnson connector
on RF board IF Freqs:
109.65MHz
Yes
Check RX
Audio
Front End.
Heard?
No
Check 2nd VCO
"Second VCO Checks"
Yes VCO
No
Locked?
Before Replacing
U301, Check 2nd
"Second VCO Checks"
2.1MHz
No
"Display Flashes
Check At
"FAIL 001""
Pin 19
U301?
Yes
Check U301 Voltages,
14.4MHz
No
Programming, &
at ABACUS
14.4MHz VCO
U301 Pin
Components.
15?
Yes
Change
Mode
Activity
Check VOCON
No
On U301
Board.
Sel Pin?
Yes
VCO.
MAEPF-25192-A
5-3
Chart C.1 RF Board Back-End
September 5, 2008