Motorola ASTRO Digital Spectra Plus Service Manual page 240

5-24
D
Measure waveform at TP403, Amplitude of
should match Figure 6-17 waveform
may vary
Make sure that R407, R400,
Yes
C405 are placed and values
OK?
are correct
No
Amplitude of
Measure waveform at R406 (left),
waveform
should match Figure 6-17
may vary
Make sure that R406, R437,
Yes
R438, C429, C402 are
OK? OK?
placed and values are
correct
Microphone No
input
Amplitude of
Measure waveform at J501-39,
waveform
should match Figure 6-17
may vary
Make sure that R406, and
Yes
C404 are placed and values
OK?
are correct
No
Inspect and repair
J501
Chart C.30 ASTRO Spectra Plus VOCON TX Modulation Failure Sheet 4 of 4
October 28, 2002
No
Repair proper
OK?
components
Yes
Replace U404
No
Repair proper
OK?
components
Yes
Replace U404
Repair proper
components
Put the radio into Test mode (CSQ 1).
Connect RF Signal Generator to the RF
input of the radio. Use Dev=3kHz,
Amplitude=-47dBm and
Freq=851.025MHz
Measure waveform at the Vocon
Connector, J501 pin 40. Should
match Figure 6-19
Yes
Waveform No trouble
correct? found
No
Measure waveform at U402, pin 2.
Should look similar to Figure 6-19
but lower in amplitude.
Make sure the following components
Waveform
Yes
are placed and soldered correctly:
correct?
R404, R405, R416
No
Measure waveforms at U402,
pins 8, 7, 11. Should look similar
to Figure 6-18
Inspect placement
Yes
Waveforms
and soldering of
correct?
U402
No
Inspect placement and
soldering of U402
Yes
Waveform
correct?
No
Troubleshooting Charts
Refer board to
Service Depot
No
Yes
Waveforms
correct?
Make sure the following components are
placed and soldered correctly and recheck
BBP waveforms: U200, Q202, Q201,
L200, Q200
No
BBP
Yes Inspect placement
waveforms
and soldering of
correct?
Patriot IC - U300
Check BBP waveforms at TP219,
TP221, and TP223. Should look
similar to Figure 6-20
Chart C.31 ASTRO Spectra Plus VOCON RX Audio Failure
6881076C25-D