LG 512W, Service Manual

Page: 40 / 104

4. TROUBLE SHOOTING
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• Replacement of a PAM
A PAM (Power Amplifier Module ; U303) may need to be replaced with new one due to following
problems.
- Can not make a call after serious damage / impact on the phone or dropping the phone.
- Can not make a call again after sending or receiving call.
- Message “Reading Power Time Out”, is displayed on the panel of equipment such as HP8960
during RF calibration for several times, then the RF calibration can not process at all.
• How to replace a PAM.
1. Using a screwdriver to disassemble the back housing carefully.
2. Use a soldering station to detach the soldered parts of main PCB and FPCB.
3. Then remove the main PCB from the housing.
4. Set a hitting gun at 500 ℃ . Then switch on the power and wait for 5 minutes.
5. Place the hitting gun 1 cm away from the top end of a PAM for 5 minutes. After hitting it up, use
tweezers (pincette) to hold both the sides of a PAM and lift it up carefully.
6. Use a solder station to adhere a little of lead on PCB pad where a PAM is replaced on.
7. Place a new PAM carefully on PCB pad.
8. Hit up a PAM and PCB pad to attach them together by using the hitting gun.
9. Assemble them to the housing after about 10 minutes.
10. After the replacement, please process the RF calibration.