Mhz Troubleshooting Charts - Motorola HT Series Service Manual

8-50

8.17 900 MHz Troubleshooting Charts

8.17.1 Troubleshooting Flow Chart for Controller (Sheet 1 of 2)
Audio from Pin F4,
NO
Check U351
LV ZIF.
INT
AUDIO
J403 Audio at
Pin 2 & Pin 3.
Check Spk. Flex
Connection.
YES
HC, U851? EXT
PTT
Radio could
NO
not PTT
externally.
Audio at
Pin E4
U851?
YES
Check HC
U851.
EXT
SPKR
J403 Pin 9 low?
ASFIC U404 Pin
14 & 15 high?
U420 Audio PA.
Maintenance: 900 MHz Troubleshooting Charts
Audio at
NO
Audio PA (U420)
input
(C447).
YES
Check
Audio PA
(U420).
NO
Audio from Pin 41
ASFIC, U404?
NO
YES Audio at
Pin 2
U404?
YES
Check ASFIC
U404.
J403
NO
OPT_SEL_1 &
OPT_SEL_2
Pin 8 & 9
low?
YES
NO
Pin 8 high?
Check
Accessories
YES
NO
YES
Check
PTT
Press PTT. Red
LED does not light
up.
YES
NO
PTT U409
Pin 53
low?
YES Check
PB504.
YES
Press PTT
Q502-2 High?
No
Check
Q502-2
voltage.
LED
YES
LED should
Q502,R501
light up.
OK?
No
Replace Faulty
Component.
Check
Accessories.
U409
YES
Check MCU.
Pin 52, 6
low?
NO
See FGU
Troubleshooting
chart.
Check
U404.