Motorola HT Series Service Manual page 97

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Audio from Pin F4,
NO
Check U351
LV ZIF.
INT
AUDIO
J403 Audio at
Pin 2 & Pin 3.
Check Spk. Flex
Connection.
YES
EXT
HC, U851?
PTT
Radio could
NO
not PTT
externally.
Audio at
Pin E4
U851?
YES
Check HC
U851.
EXT
SPKR
J403 Pin 9 low?
Pin 8 high?
ASFIC U404 Pin
14 & 15 high?
U420 Audio PA.
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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
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.