Motorola SSETM 5000 RX RFPage 3

November 11, 2004 6881094C12-A
9-22 Troubleshooting Charts: RX RF
RX RF—Page 3
TP502
=0Vdc?
No
No
Yes
Yes
Repair
defects
MeasureRFlevelsatfirstpreselector
filterandcomputefilterloss.
UHF:TP13,U401-3
No
Yes
Loss<3db?
MeasureRFlevelsatLNA
andcomputeLNAgain.
UHF:U401-1,TP402
MeasureRFlevelsatsecondpreselector
filterandcomputefilterloss.
UHF:TP402,TP403
Gain
about
+12dB?
2
6
No
Yes
MeasureRFandIFlevelatmixer
andcomputemixerconversiongain.
UHF:TP403,TP404
Loss
<3dB? 8
No
Yes
Measure
controlvoltage
atTP502
No
Yes
Fvco
toolow?
UHF:<71.1MHz
RemoveAbacusshieldand
inspectsecondLOVCO.
UHF:SH501
TP502
=5Vdc?
3
5
5
No
Yes
Replace
VaractorD550
Check
LNA
Check
mixer
Visual
examination
OK?
No
Yes
MeasureIFlevelatXTALfilter
andcomputeXTALfilterloss.
UHF:TP404,TP12
Mixer
gainabout
4dB? No
Yes
Noproblem
found
Loss
<3dB? 7
MAEPF-27472-B
TP502
(Vdc)
TP501
(MHz)
Fvco
1.7
3.7
71.1
75.6
UHFR1