Read LG 42LG72 (CHASSIS:LA86B) Service Manual online
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(6) Spdif & Coaxial - Audio(Out)
Check the input of JK500, JK501.
Can you see the normal waveform?
Yes
After checking audio signal line, you should
decide to replace item or not.
No
Check the output (Pin AP11) of BCM355x(IC100).
Measure waveform at R2638 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
After checking the Jack, you should
decide to replace item or not.
(7) MNT out - Audio(Out)
Check the input of JK704.
Can you see the normal waveform?
Yes
After checking audio signal line, you should
decide to replace item or not.
No
Check the output (Pin AN28, AP29) of BCM355x (IC100).
Measure waveform at R685, R686 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
After checking the Jack, you should
decide to replace item or not.
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