Hytera MD652, Service Manual

Page: 141 / 207

VHF1 (136
‐
174 MHz)
Troubleshooting Flow Chart
33
6.4
Receiver Circuit
Q2021 (9V1A) output
is normal?
No Receive
Q2002(9V1A_RX)
output is normal?
Check the power-
on circuit
Check Q2021 and
Q2002
No
No
Yes
Front panel output is
normal?[1]
Replace the front
panel
Yes
Yes
No
Second LO is
normal?[3]
Input an IF signal of 44.85
MHz to test whether it is
normal?[2]
Check Q6004
and peripheral
components
No
Yes
Yes
Yes
No
No
No
Check Q6002
and peripheral
components
Yes
TP6157 output is
normal?[5]
Second LO outputs a
18MHz signal?
Sensitivity at C6034 is
normal?[4]
Sensitivity at C6039 is
normal?[6]
Yes
Check D6102,
D6103 and
peripheral circuits
No
Check Q6102, D6104,
D6105 and peripheral circuits
No
Yes
Check T6100, T6101,
D6106 and relevant
components
Check RX
VCO and LO
amplifier
Description of Normal Situations:
[1] During sensitivity test, the communication test set can demodulate the audio signal at TP3002 and TP3003 .