Is
5 VDC present
at pin13 of CN90 on the
main module when AC is
applied?
Does
a 3.3 volt DC
level appear at pin 2
of CN91 when the on/
off button is
pressed?
Yes
Suspect a problem with
the power supply module.
No
Is a
power protect
level (3.2 VDC)
present at pin 1 of
CN91 when AC
is applied?
Yes
No
Suspect a problem with
the power supply module.
Does
the secondary
12 volt source appear
at pins 9, 10, and 11 of
CN90 when the on/off
button is
pressed?
No
No
Suspect a problem
with the SYSCON
circuit located on the
Main module.
Yes
Yes
Suspect a
problem with the
Main module.
Dead Set No
Sound/ No
Picture
Does
3.2 volts (AC
Detect) appear at pin
3 of CN91 when
power is
pressed?
Yes
No
Does a blink code
appear when the unit is
turned on?
Yes
No
Use the blink code chart to help diagnose the
problem. Over voltage( Mode 20) indicates
power supply problems and bus line problems
(Mode 19) indicates a defective main module.
SMART2009-LCD909-V5 Page 4 of 14
