User's Manual

25
8.4 When Modulation Is Not Made
No
→
Adjust the S/W
modulation
amount.
No
→
Check if signals are incoming to
the modulation input port of the
Tx VCO (R114) end.
Check if signals have arrived to
Pin No. 15 of U505, and check
devices around U505.
Yes↓
↑
No
Are Pins No. 22 and No. 23 of
U505 normal?
Select Q511 and Q512 as follows:
12.5KHz channel: High
25KHz channel: Low.
Yes↓
Check Pin 19 of U505.
Check Pins 1, 8, and 7 of U507.
Is not output normal?
No
→
Check the power supply
status and Pin 6 of U505.
Replace them, if necessary.
Yes↓
Do Pins No. 16, No. 15, and No. 14
of U505 normally function?
No
→
Check the power supply
status and the clock of
U505. Replace U505 if
necessary.
Yes↓
Do OP amplifiers of U507D, B, C,
A normally function?
No
→
Check MIC1 and the power
supply status of Q513.
Replace U507D if necessary.
Yes↓
Check MIC1 and PTT S/W.
Do Q513 and the D508
normally function?
No
→
Check the PTT S/W, Q513,
and the D508, and replace
them if necessary.
Yes↓
Normal