Midland 70-1341, Service Manual

Page: 34 / 68

SERVICING
70-1341/1344/1441/1444
4 - 10
NO
Troubleshooting Chart 3 – 4a — Receiver Problem
NO YES
NO
YES
NO
NO
YES
NO YES
YES
YES
YES NO YES
START
No audio?
Suspect Q201
Suspect Q201,
L201, L202, L204,
L205, L206 or L207
C549, C550
and L518
OK?
NO
NO
NO
YES
YES
D202, L209
and L210 OK?
No signal, or
weak signal?
Audio present
at IC202 pin 9?
D501
thru D505
unbiased in RX
mode?
Suspect D501
thru D505
Suspect IC404
Check for audio
present at IC203
pin 1
Poor
sensitivity?
Go to
1
Audio
present at
IC404 pins 1, 7,
8 and 14?
Suspect C549,
C550 or L518
Suspect D202,
L209 or L210
Suspect IC901
Antenna OK?
(Next page)
NO
Go to
2
(Next page)
Suspect
Antenna
NO
YES
Q201,
L201, L202,
L204, L205,
L206 and L207
OK?
Audio
present at
IC401
pin 19?
YES
Is freq.
At Q717 =
Channel freq. +
45.0 MHz
Suspect Q717 or
the phase-lock loop
NO
YES
Audio
present
at IC401
pin 22?
Suspect IC401
YES
Wave
form present
at IC401
pin 15?
NO
Wave
form present
at IC901
pin 60?
NO
YES
Check path
from IC901
pin 60 to IC401