Motorola SSETM 5000 - Manual (Page 125)

6881094C12-A November 11, 2004
Troubleshooting Charts: RX RF 9-21
RX RF—Page 2
Q501-c
= 5.0 Vdc?
No
No
No
Yes
Yes
Yes
Repair
Defects
Visual
examination
OK?
Check Voltage
Regulator U1
Q501-e
= 3.7 Vdc?
No
Yes
Replace
Q501
Replace
Q502
Remove SH501
and inspect
2nd LO VCO
Signal
Present?
Measure 2nd LO at
TP501 on PCB side 2
No
No
Yes
Yes
LO Freq.
OK?
UHF: 71.1 MHz
Measure
RXCK, P1-5
RXFS, P1-6
RXDO, P1-12
Observe
0 to 3 Vdc
digital signals
Measure
bit clock rate
(Fbit) at RXCK
Levels
OK?
1
3
5
No
Yes
RXFS = 20 kHz
sync pulse
Fbit =
1.2 MHz?
4
No
Yes
No
Yes
RXFS
OK?
RXDO = 24-bit I,
24-bit Q, 8-bit
AGC. AGC varies
with RF level
Go to
VOCON RX
AUDIO flowchart
RXDO
OK?
5
5
2nd LO DC bias
MAEPF-27471-B