Hytera PD502, Service Manual, Page: 32 / 136

VHF (136-174 MHz) Troubleshooting Flow Chart
26
6.2
Receiver Circuit
The second LO is
normal?[6]
No
No
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No Receive
No
Yes
Yes
Check RX
VCO
Yes
No
Yes
No
No
Yes
3V3A_RX output is
normal?[1]
LNA_Out outputs
normally?[8]
Input signal is
normal?[12]
Yes
Completed
No
3V3A_RX_RF output
is normal?[2]
Check Q6004
Check Q6005
Check Q6006,
Q6007
The static working
point of Q6005 is
normal?[3]
The static working point
of Q6006/Q6007 is
normal?[4]
Input IF signal via
U6001PIN47 to
check whether IF
sensitivity is
normal?[5]
18MHz crystal oscillator
is normal?[7]
Check Q6003 and
peripheral
components
Check Q6002 and
other appropriate
components
LO signal outputs
normally?[9]
First IF outputs
normally?[11]
RX_LO outputs
normally?[10]
Check Z6001, Q6006, Q6007
and peripheral circuits
Check Q6005 and
front-end RF circuit
Check signal frequency,
amplitude and modulation
information