Tait TM8100 mobiles Service Manual page 334

Task 34 —
Repair PIN switch
334 Transmitter Fault Finding (>25W)
If the RF power at the PIN switch is low, the switch is not drawing the
expected current or the diode is faulty. Check the circuit as follows:
1. Remove the
PIN TOP
2. Perform a diode check of D307 (VHF and K5 band) or D3507
(UHF) (see Figure
replace D307 or D3507, and go to
Check the +9 0_
3.
V
resistors on the bottom-side of the PCB (see
Figure 11.29 for VHF and UHF, and
band):
VHF: R389 and R390
■
UHF and K5 band: R3000, R389 and R390
■
If any resistor is faulty, replace the resistor as well as D307 (VHF and
K5 band) or D3507 (UHF). (A faulty resistor is likely to have resulted
in damage to D307 or D3507.)
4. With the test lead still connected to the test set, enter the CCTM
command 326 5 to set the transmitter power level to the maximum.
Enter the CCTM command 101 x x 0, where x is the lowest
5.
frequency (in hertz) for maximum power, as given in
(B1), Table 11.9
Table 11.12 (K5).
Enter the CCTM command 33 to place the radio in transmit mode.
6.
Again measure the RF output power. This should be:
RF output power: more than 70W (VHF)
7. Enter the CCTM command 32 to place the radio in receive mode.
Enter the CCTM command 101 x x 0, where x is the highest
8.
frequency (in hertz) for maximum power, as given in
(B1), Table 11.9
Table 11.12 (K5).
9. Repeat Step 5 to
10. Remove the test lead and test capacitor, and resolder the blocking
capacitors C361, C362 and C363 for VHF and UHF or C363 for the
K5 band (see Figure
11. If the power in both the above cases is now correct, the fault has been
rectified; go to
failed; replace the board and go to
can.
11.27). If it is not faulty, go to
Step
supply to the PIN switch via the following
TX
(G2), Table 11.10
more than 60W (UHF)
more than 52W (700MHz)
more than 58W (800MHz)
(G2), Table 11.10
Step 7.
11.27) in position.
"Final Tasks" on page
"Final Tasks" on page
© Tait Electronics Limited November 2007
Step 3. If it is,
4.
Figure 11.28
Figure 11.29 for the K5
Table 11.8
(H5), Table 11.11 (H7), or
Table 11.8
(H5), Table 11.11 (H7), or
163. If it is not, the repair
163.
TM8100/TM8200 Service Manual
and