Fgu Circuit - Hytera PT580 Service Manual

FGU Circuit

No
Check whether
Q6502 is normal. [5]
Yes
No
Check the varactor. [6]
Yes
No
Check whether
Q1001 is normal. [7]
Yes
No
Check whether
Q1002 is normal. [7]
Yes
Description:
[1] The CP voltage is 0.5~4.5V.
[2] The voltage at Pin4 of Q6503/Q6506 is 5V.
[3] The varactor is not damaged.
[4] The output voltage by Q1003/Q1004 is 4.8V.
[5] The voltage at Pin4 of Q6502/Q6504 is 5V.
[6] The varactor is not damaged.
[7] The output voltage by Q1001/Q1002 is 4.8V.
[8] The voltage at Pin4 of Q6504/Q6506 is 5V.
[9] The varactor is not damaged.
[10] For Q1005/Q1006, the voltage at the collector is 4.8V; the voltage at the grid is 1.8V; and the
voltage at the emitter is 1.2V.
[11] For Q1007, the voltage at the collector is 4.5V; the voltage at the grid is 0.3V; and the voltage at the
emitter is 0V.
[12] For U1001, the voltage at Pin1 is 3V (i.e. voltage at the R1002 end); the voltage at Pin2 is 5V (i.e.
voltage at the R1004 end); Pin9 provides 12MHz sine signal (amplitude: 0.8V).
Check Q6502 and Check whether
Q6504. Q6503 is normal. [2]
Replace the varactor. Check the varactor. [3]
Check whether
Replace Q1001.
Q1003 is normal. [4]
Check whether
Replace Q1002. Q1004 is normal.
[4]
Abnormal FGU
CP voltage for TX/RX LO [1]
No
Replace Q6503 and
Q6506.
Yes
No
Replace the varactor.
Yes
No
Replace Q1003.
Yes
No
Replace Q1004.
Yes
Check U1001. [12]
No
Replace U1001.
27
Service Manual
No
Check whether Replace Q6504 and
Q6504 is normal. [8]
Yes
No
Replace the varactor.
Check the varactor. [9]
Yes
No
Check whether
Q1005 is normal. [10]
Yes
No
Check whether
Q1006 is normal. [11]
Yes
No
Check whether
Q1007 is normal. [11]
Yes
Q6506.
Replace Q1005.
Replace Q1006.
Replace Q1007.