Motorola MTM700 Detailed Service Manual page 307

TROUBLESHOOTING CHARTS (800MHz) MTM700 Mobile Radio / Detailed Service Manual
Receiver Troubleshooting (Sheet 2)
Measure Bias Voltages on IF amplifier Q5201
(5.1V at collector and 0.9V at base).
ABACUS section can be checked by spraying an
IF signal at 73.35MHz into the IF section or apply-
ing directly to C5125.
Make sure that 5V_FN is present at C5139 and 3.3V
at pin5 U5102 and U5103.
If 5V_FN is not present at C5139, change U5101.
NO
Are Bias volt-
ages correct?
YES
ABACUS Troubleshooting Chart
Does the
radio receive?
NO
Is Sampling Clock @
18MHz present at
C5197?
YES
Is the second IF @
71.1MHz present
@ C5186?
YES
Check R5209, R5208,
R5207, R5205.
YES
Repeat Receiver Troubleshooting if radio still
does not receive.
NO
Check that transistor Q5190 Bias voltages are approx-
imately: Base 3.8V, Collector 4.7, and emitter 3.2V.
Voltage at R5196 should be about 1.5V.
Check for correct component placement in
the 18MHz section.
NO
Check transistor Q5180 Bias voltages:
Base 2.8V, Collector 4.7, and emitter 2.2V.
Voltage at R5186 should be about 1.1V.
Check for correct component placement in
the second IF section.
9.2 - 15
Tetra Com Script for Rx Test:
TEST_ENTER
DELAY 10
Check for "Radio HW is READY"
MODE IDLE
FREQ RX 860.525
L1TIMER ON
AVE 10
MODE RSSI
GO
Use STOP to terminate RSSI reading