haribagibagi: Nokia 3120c power button problem

ASALAMUALAIKUM WR WB

Identification of cases

1. When the batteries are installed directly start the cell
2. Phone on/off Button does not work

Note scheme 1 to identify the path from the on/off button to power ic Avilma

Clearly visible from the schema above that standard on/off mobile phones driven by two electronic components only. First is the on/off button or S2425 and a resistor ground coupling i.e. R2403.
Next see the scheme 2

When the on/off button is pressed it will send it power to the ic Avilma. And for the first time avilma will send signals of supply to flash ic then to the cpu/upp more we know as VIO.

When the cases like case above, when you reattach the battery you have been disconnect from the phone, then the phone will be instantly start without you touching the on/off button. The instinctively amateurs technician who just learned, my brain sends signals of a notification that an error occurs on the component that connects the power supply from the phone to the power ic avilma. This will probably happen when :

a. The on/off button is broken, jammed, and shorting

b. Short circuit occurs on the on/off area caused by components that relate directly to the power supply line from the on/off button to power ic avilma.

How to cope with these problems, okay with regard to the scheme of the two pictures above then we can start doing the examination of S2425 and R2403. Because only two of the component that is directly affecting the power supply to the power ic avilma.

Prepare your multi tester to measure X 1 ohm. Set the measuring needles so that the pointed right at the number 0 (zero) in the multi tester, or until your multi tester led indicator lights up. I recommend to use an analog multi tester, because digital do not have a good enough response to do checking of the electrical components shorting.

First check the power supply pin on the inner foot on/offbutton S2425 to the ground. See the results shown by the multi tester (normal conditions will point to the number of about 4-5 ohm). If the needle your multi tester point to point 0 (zero) and the multi tester indicator lamp lights up it is an indication of the occurrence of shorting. Take off on/off button from its position and checking in the removed condition . If the result does not shorting occur when examined in the removed condition, please check your resistor coupling R2403 from inner pin to ground. How to attach, put the black on R2403 inner and red to ground.

When the needles measure point to point 0 (zero) ohm then this component the cause of shorting.Take off R2403 and not need to be replaced, let it without resistor coupling.

So the simple of description by an amateur technician, who are learning to repair damaged cell phones. Hopefully this written can give more support to learned to other colleagues who are also just learning. CONTINUE TO LEARN AND NEVER DESPAIR, DISCOVER ALWAYS NEW CHALLENGES.