HYT Science and Technology Co TM-800U1 Mobile Radio User Manual

Shenzhen HYT Science &Technology; Co Ltd Mobile Radio

Contents

Users Manual I

TM-800 UHF SERVICE MANUAL
123
Troubleshooting Flow Charts
Normal Power-on
alert tone?
MCU
Check
RF circuit can’t
be driven
Yes
Speaker works
well?
No
Replace the
speaker
No
`
9.8304MHz works
normally?
Yes
Read available
or not?
Yes
Q117 works
normally?
Replace
Q117
Check 5V
MCU works well
Pin10 is of
high level?
Check the
control circuit
Check read
circuit
Reset
No
Yes
Yes
Yes
No
No
Yes
TM-800 UHF SERVICE MANUAL
124
Normal power
supply?
VCO
Check
Replace Q116
No
Rx oscillates ? And
CV voltage is
normal?
Yes
Q706 works
normal?
No
`
Check Q703
outputs normally? Check Q703
Normal
feedback? Check Q124
Check power
supply circuit.
Check CPU data
circuit.
16.8MHz
oscillates?
Q705 works
normal?
Replace Q706
Replace
Q705
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
TM-800 UHF SERVICE MANUAL
125
Power supply of AF
IC126 is normal?
No receive
Output of IC126 is
normal?
Output of electronics
volume IC125 is
normal?
Check IC126
Output of IC104 is
normal?
The 2nd local oscillator
works normally?
L135 works normally?
Is there any input in
IC119 PIN16 IF?
Is there any RF signal?
Replace L135
Check X105
Check IC125
Check work status of
IC119 &peripheral
components
Check VCO
FPC & Speaker
work normally?
No
No
No
Check Q601 pass
Yes
Output of IC106 is
normal? Check IC104
Output of IC121 is
normal? Check IC106
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
No
No
No
No
No
No
Check power
supply circuit.
TM-800 UHF SERVICE MANUAL
126
No output
Power supply
works normally?
Check power
supply circuit
Check Q131 &
Q110
Check driver stage.
Check transistor
Bias voltage and
low pass network
Repair
transmission
network.
Check the suited
network.
VCO maintenance
Flow chart
Replace Q128
Replace Q127
Completed
Completed
Completed
Control voltage is
normal?
Current is
normal?
Driver stage is
normal?
Normal Power?
Normal power?
Normal power?
No
Yes
Low
High
NoYes
Yes
Yes
Yes
No
Yes
No
No
TM-800 UHF SERVICE MANUAL
127
Exploded View
8
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34
33
32
31
30
29 28 27 26 25 24 23 22 21
20
19
18
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11
10
7
6
5
4
3
2
1

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