Read LG 42LG72 (CHASSIS:LA86B) Service Manual online
- 21 -
(4) HDMI - Audio(In)
Check DDC communication lines.
(IC601, IC602, IC701)
Yes
Check the output of PI3HDMI341ATR(IC600).
Can you see the normal waveform?
After checking the Power of this chip, you should
decide to replace this or not.
No
Check input connect JK600,JK601,JK708
Can you see the normal waveform?
Yes
JK600,JK601,JK708 may have problem. Replace
this Jack.
No
Check HDCP communication lines(IC102)
Yes
After checking the Power of this chip, you should
decide to replace this or not.
No
After checking the Power & Select Pin & Etc of
this chip, you should decide to replace this or not.
No
(5) Speaker - Audio(Out)
Check the input (Pin 17,18,19) of NTP3000 (IC501).
Can you see the normal waveform?
Yes
Check the speaker output wafer P501.
Can you see the normal waveform?
After checking audio signal line, you should decide to
replace item or not.
No
Check the output (Pin AK25,AL25,AJ25) of BCM355x (IC100).
Measure waveform at R2635,R2636,R2637 because it’s more
easy to check. Can you see the normal signal?
Yes
This board has big problem because Main chip (BCM355x)
have some troubles. After checking thoroughly all path once
again, You should decide to replace BCM355x or not..
No
Check the output (Pin 30,31,36,37,47,48,53,54) of NTP3000
(IC501). Can you see the normal waveform?
Yes
Check the connector & Speaker.
Yes
Check the output (Pin 30,31,36,37,47,48,53,54) of
NTP3000((IC501).Can you see the normal waveform?
No
After checking audio signal line, you should decide
to replace item or not.
No
Click on the first or last page to see other 42LG72 (CHASSIS:LA86B) service manuals if exist.