User's Manual

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?

Replace the

speaker

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

Yes

PAGE 1
TM-800 UHF SERVICE MANUAL Troubleshooting Flow Charts MCU Check Normal Power-on alert tone? Yes RF circuit can’t be driven No Replace the speaker Yes Read available or not? Check the control circuit No Speaker works well? Yes 9.
PAGE 2
TM-800 UHF SERVICE MANUAL VCO Check Normal power supply? No Replace Q116 No Q706 works normal? Yes Rx oscillates ? And CV voltage is normal? Yes Q705 works normal? No Yes Replace Q706 Check Q703 outputs normally? ` No Yes Check Q703 Yes Normal feedback? No Check Q124 Yes 16.8MHz oscillates? No Check power supply circuit. Yes Check CPU data circuit.
PAGE 3
TM-800 UHF SERVICE MANUAL No receive Power supply of AF IC126 is normal? No Check power supply circuit.
PAGE 4
TM-800 UHF SERVICE MANUAL No output Yes Yes Current is normal? No Power supply works normally? No Check power supply circuit Low Check Q131 & Q110 Control voltage is normal? High Check transistor Bias voltage and low pass network Check driver stage. Repair transmission network. Driver stage is normal? No No Check the suited network.
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TM-800 UHF SERVICE MANUAL Exploded View 1 2 3 4 5 6 41 7 40 8 39 9 38 10 37 11 36 12 35 13 34 14 15 33 16 32 17 31 18 19 30 20 29 28 27 26 25 24 23 127 22 21