Hytera MD652, Service Manual

Page: 143 / 207

VHF1 (136
‐
174 MHz)
Troubleshooting Flow Chart
35
6.5
Frequency Generation Unit (FGU)
VCO
Check
Replace U2009
and U2008
No
VCO oscillates
normally?[1]
Yes
Q8002 and Q8007
are normal?[2]
No
Check D8007, D8008,
D8009, D8010, D8013,
D8014, D8015, D8016
Check feedback
circuit
Crystal 19.2 MHz
oscillates normally?[7]
Check 19.2 MHz
Oscillator circuit
Check CPU data circuit
Replace Q8002 and
Q8007
Replace Q8002 and
Q8007
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
U2009(5V) and
U2008(3.3V)
voltages are normal?
Q8008(4.3V)
voltage is normal?
Yes
No
Replace Q8008
Q8002 and Q8007
are normal?[3]
Feedback signal for
U8001 is normal? [6]
TP8002 CV is
normal?[4]
No
PLL U8001 is
normal?[5]
Yes
Replace PLL
U8001
No
Check U8002 and U8003
Description of Normal Situations:
[1] Detect the oscillation frequency of RX TP6107 using a spectrum analyzer.
[2] Check whether Q8001 and Q8003 are turned on and output 3.6 V voltage.