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TROUBLESHOOTING
Before troubleshooting, prepare your unit as follows:
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Connect the power supply.
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Turn volume control fully clockwise so that it is all the way up.
Item Symptom
Cause/Remedy
1
Unit is not able to turn on.
!"
Check the power voltage and power switch.
!"
Check to see if regulator IC8 defective.
2
No sound with AF signal
applied to pin 6 of IC6.
!"
Check to see if IC1 and /or associated components is
Defective.
!"
Check to see if speaker on control circuit VR201, IC10A,
IC10B, is defective.
3
Squelch circuit inoperative.
!"
Check to see if VR203 is defective.
!"
Check to see if IC4 is defective.
4
No receiver (RX)
!"
Check to see if IC11 is defective.
!"
Check to see if IC7 audio output at pin 9 is defective.
!"
Check Q12.
!"
Check 21.4MHz output of first mixer Q10.
!"
Check 21.4MHz output of crystal filters F1, F2.
!"
Check 21.4MHz output of first IF amplifier Q11.
!"
Check 450kHz signal from ceramic filter F3.
!"
Check to see if VCO circuit is defective.
!"
Check to see MCU is defective.
5
Low receiver sensitivity
!"
Check to see if antenna is bad connecting.
!"
Check to see if the output from Q9, Q10, Q11 and F1
F2 is
defective.
6
No transmission (TX)
!"
Check to see if the PTT switch is defective.
!"
Check to see if Q13 is defective.
!"
Check to see if power transmit circuit Q1, Q2, Q3 are
defective.
!"
Check to see if VCO circuit is defective.
!"
Check PLL control voltage if it reads 2
±
0.2V at 156.05MHz.
7
Poor or no modulation
!"
Check to see if the microphone or MIC jack is defective.
!"
Check to see if IC205 and/or its associated components are
defective.
8
Deviation of transmit frequency
!"
Check the frequency of 20.950MHz crystal X2.
!"
Adjust VC2 and verify the transmit frequency.
