Unable To Power On; Lcd Issue; Keypad No Function - FLY MC155 Service Manual

not; 2. disassemble the antenna and check whether connection area on PCB is clean or not. If not
clean, please wipe it with alcohol.
Then, after antenna problem is moved out, then we can test PCB directly to verify this problem.
Normally it could be soldering problem of components about RF part. We can check soldering
status or adding bonding to make sure the root cause.

2. Unable to power on

This kind of problem is a common problem. Firstly, we should check battery and battery
connection. Check whether there is dirty or not at battery connector pad or battery connector on
PCBA. Secondly, check whether there is short circuit or not and whether there is current or not
when power on. This is normally CPU problem. If power on sound could be heard or keypad light
is on, then need to check soldering status for LCD.

3. LCD issue

Check LCD soldering status first. Adding bonding if needed. If still there is problem, check the
soldering pins whether it is short circuit.

4. Keypad no function

Normally keypad no function problem is caused by below: dirt on DOM, keypad position shifting,
or loosing elasticity. Normally this kind of problem is on single key or some keys.
If all keys have no function, please check CPU. But sometime it may due to elasticity problem of
keypad.
MC155 Service Manual V1.0