Colour Television Chassis: M123A
33
Yes
Symptom: raster ok, no
picture, no sound, sparse
noise dots
Apply the pointer of
multimeter at R X 1 K
Ω
,
connect one probe to GND,
use another to touch P42 of
IC101. Are there
interference particles
flashing on the screen?
Unsolder a pin of C110, apply the
pointer of multimeter at R X 1 K
Ω
, connect the red probe to
GND, use the black probe to
touch B of Q101. Are there
interference particles flashing on
the screen?
Yes
Replace the Tuner
No
Is the voltage at
P29, P36 of
IC201 ok?
No
Check and repair
the +9V power
supply
No
Bridge a capacitor of 1000pF between
the input and output of Z101. Apply
the pointer of multimeter at R X 1 K
Ω
, connect the red probe to GND,
and use the black probe to touch B of
Q101 Are there interference particles
flashing on the screen
Yes
Replace Z101 (SAW)
Does the IF
pre-amplifier
work
normally?
Yes
Check & repair
the IF
pre-AMP. circuit
No
Figure 5 Sparse noise dots
No
