18
POWER-BLOCK check
*
*Note : the Waveform of U304 pin 2 can determined the power situation
1.
stable rectangle waveform with equal duty, freq around 150K-158KHz
that means all power of this interface board is in normal operation
,and all status of 5V & 3.3V is working well
2.
unstable or uneven rectangle waveform without same duty, that means ABNORMAL operation was
happened, check 3.3V or 5V ,if short-circuit or bad component
3.
rectangle waveform with large spike & harmonic pulse on front side , means all 3.3v is no load, U200
Gmzan2
was shut-down, and only U302
MCU
still working , that means the monitor is in power saving
status , all power system is working well .
OK
Check U304 pin 2 is a stable rectangle wave?
Around 150k-158kHz stable rectangle wave
with equal duty without any spike or harmonic
pulse?
OK
NG, with
harmonic
pulse
Check U304 pin 2 is a unstable rectangle wave ?
The interface board power is good
Measure input power at U304 LM2596 pin 1=
12V ?
Check
ADAPTER
and connector
if
loose?
NG
NG
Check all 3.3V & 5V power, there is
short circuit or bad component was
happened
OK, unstable wave
The interface board is in power-
saving state, press power key to wake
up & check your signal input
