LG CM8440 Series - Booting in CD;Usb Function

3-7
ONE POINT REPAIR GUIDE
NO BOOTING IN CD/USB FUNCTION
After you turn on power key and displayed message in the following order
(HELLO --> VOL XX --> CD or USB) on VFD,
it will not display other message on VFD, and it will not boot-up normally.
4-2. CRYSTAL (X500)
4-2-1. Solution
Please check and replace X500 on MAIN board.
4-2-2. How to troubleshoot (Countermeasure)
1) If 3.3 V & 1.2 V is normal, check Reset ‘High’ of IC501 pinT12 on MAIN board.
 If MAIN_RESET isn’t high, check MICOM (IC101) pin40.
2) If MAIN_RESET is high, check the soldering status of 24 MHz crystal (X500).
3) If the crystal (X500) doesn’t oscillate, check R508, R509, C502, C503 around crystal (X500).
 If there’s no defective component, then replace X500.
4-2-3. Service hint (Any picture / Remark)
p
v
IC500
X500
< Signal check point >
< Signal waveform >