Motorola SSETM 5000 9.10 VCO TX/RX Unlock

6881094C12-A November 11, 2004
Troubleshooting Charts: VCO TX/RX Unlock 9-15
9.10 VCO TX/RX Unlock
MAEPF-27398-A
VCOTX/RX
unlock
<0.6Vdc
>11.0Vdcor
drifting?
3VatTP5?
Yes
Yes
Yes
Yes
Yes
No
No
No
No
Yes
Yes
Frequency
detected?
VCOlocked?
No
Yes
No
5VatTP3?
Check
VOCONboard
Checkparts
aroundBJT.If
OK,replaceBJT
Checkcontrol
voltageat
TP243
Checkparts
aroundU1.If
OK,replaceU1
Aux.line
4highforTX
orlowforRX?
No
FET
drainvoltage
0V?
Checkparts
aroundFET.If
OK,replaceFET
No
BJT
emittervoltage
>1.2V?
Checkparts
aroundU250.If
OK,replaceU250
Yes
No
Ispin
19ofVCOBIC
lowforRXand
4.5forTX?
Remove
VCObuffer
shield(SH302)
Checkparts
aroundQ302.If
OK,replaceQ302
Checkparts
aroundU2.If
OK,replaceU2
Remove
VCOshield
Checkparts
aroundU202.If
OK,replaceU202
"Sniff"
frequencynear
VCOshield
CheckifVCO
islockedusing
spectrumanalyzer
Sniff:Usinganinductivefieldprobe
asanantennatomeasure
frequency.Placetheprobe
approximately1/2inchaway
fromcomponentstobesniffed.
Q210Q214
FieldEffectTransistor(FET)
Q211Q215
Bi-polarTransistor(BJT)