Troubleshooting Guide - LG LPC-M155X Service Manual

SECTION 3. ELECTRICAL SECTION
❏ TROUBLESHOOTING GUIDE
• MAIN PART
1. AUDIO OUT
No power at IC701 pin1, 12
Yes
Is B + applied to pn701?
Yes
Is Q703, 704 normal?
Yes
SW 702 check
2. TUNER
Tuner Abnormal
Yes
Does 4.5V come out at
IC101 pin6?
Yes
Does signal come out at
pin13, 14?
Yes
SW 702 check
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Only for training and service purposes
No
No
Fuse open?
Yes
Fuse change
No
Replace
Q703, 704
No
Is B + applied to
Q102?
Yes
Q101, 102 check
No
IC101 check
- 3-1 -
No
D901~904
normal?
Yes
Transformer check
No
Q901, ZD901 check
Replace diode
LGE Internal Use Only