Motorola MTX series Theory/Troubleshooting Manual

TROUBLESHOOTING FLOW CHART #7A
(VHF/UHF, Closed Architecture, No Transmit Deviation)
JEDI No TX Deviation
Troubleshooting Chart
ISS.
CORREC AS MARKED
ILLUSTRATOR DATEENGINEERDATE PROGRA
DESCRIPTION
TECHNICAL
DWG. N
LETTERING SIZE:
REQUIRES:
EDITOR DATECHECKERDATE
Illustrato
O
SW
12/16/92
3/31/93
JWB
No TX Deviation
NO
YES
Audio &
Voltage at
J301-3?
Check Continuity Between J301-3 & J704-3
Audio &
Voltage at
U204
Pin 5?
Audio &
Voltage at
U204
Pin 30?
NO
YES
Check C303 & J301-3 on Jumper Flex
Replace U204 Suspect R208
Audio &
Voltage
Between
C231 &
C233?
Check for Solder Joint & Broken Runner
Voltage
Between
R207 &
R208?
Audio
Between
R207 &
R208?
VSF*
at
R208?
Voltage
at
CR202?
Check U204
C225 OK?
Replace C225
Suspect L218
Check U204
Suspect R207 or C231
YES YES YES
NO
NO NO
NO
YES YES YES
NO NO
NO
YES
EXT
MBEPF-23276-O
Setup: Injects 80mV: 1kHz sinusoidal tone into Ext. Mic Path
Check
Audio
J701-14
Check
Audio
Pin 54-U701
NO
Check Continuity between Pin 14- J701 & Pin 3-J403
Check
Audio
Pin 13-U701
Change U701
Check
Audio
Pin 3-J301
YES YES
YES
NO
VDC at
MK401
and Gnd.
YES
NO
Check Continuity between V Gnd MK401 = 2k
NO
Acoustic Couple 1k tone to Int. Mic.
Check
Audio at
Pin 2-U701
Check Components R701, L710, R703, C779, & C706
NO NO
Check Continuity between Pin 54- U701 & C705. Check components R702, R758, & L701 Check Continuity between Pin 13- U7018 Pin 3-J301
NO NO
YES YES
INT
* VSF = Voltage from Super Filter (U204, Pin 19) 4.6VDC
46

Motorola MTX series Specifications

General

Brand	Motorola
Model	MTX series
Category	Portable Radio
Language	English