Where is the missing part in this multi-sim mobile phone

[yo2550]

The phone cannot be turned on. I tried twisting the whole phone back and forth then the plastic case on the back pushed the part out of the pcb. I noticed there is a missing part near the SIM1 slot.

Take a look at the pictures. There is a + sign on the left and right.
I assume the missing part would be the same part on the left.

The problem is I do not know what it is.





I remove the left one and tested it with multimeter in diode mode. It looks like it is an diode because the meter shows value(850) only on one bias testing.

If it is an diode, what number should I use? Any ideas?

Thanks.

 

[yo2550]

More question. After looking at the pcb, it looks like the missing part is responsible to only SIM1. So do you think it is a major problem for not being able to turn on the phone?

 

[burt007]

I agree with yo2550 that should have nothing to do with power being turned on or off. Look else-where for the problem.

More question. After looking at the pcb, it looks like the missing part is responsible to only SIM1. So do you think it is a major problem for not being able to turn on the phone?

 

[BradtheRad]

What would be great is if the missing part were to turn up. Did you search inside the phone? Under plates and panels? The part might yet be wedged somewhere. Did it fall on the rug maybe?

It is entirely possible it is a diode inline with the power supply, for protection from reverse polarity.

It is entirely up to you whether to risk the chance that you might repair the phone, or ruin it.

A plain silicon diode could be all you need to bridge across the solder pads. However it might conduct excessive current, so in case that contributed to the phone's demise...
As an alternate, consider a few k-ohm resistor (enough to conduct a mA). Press the 'On' button. Press on the pcb a little. Keep watching the screen for the slightest activity. Try a lesser value resistor. Etc.

 

[yo2550]

Tried 2.2k and 560ohm smd resistors, still cannot turn the phone on. Tried charging the phone for 10-15 hours, the charging screen didn't appear. It seems the power didn't go to the battery. Must be some power section problems.
Tried asking for a diagram from a seller, didn't have it. May have to go to local phone repair shop.

 

[FvM]

Soldered parts rarely "fall off" a PCB without a trace, e.g. broken pads. More likely these are "N.P." (not populated) parts, assembly options that aren't needed in the present board variant.

 

[burt007]

Re: Please help me figuring out a missing part in this multi-sim mobile phone

doesn't cost money to give the info about the phone as to make and model no. etc. because if somebody has the same phone than he or she can open and look at it.

Is it a big secret?

The phone cannot be turned on. I tried twisting the whole phone back and forth then the plastic case on the back pushed the part out of the pcb. I noticed there is a missing part near the SIM1 slot.

Take a look at the pictures. There is a + sign on the left and right.
I assume the missing part would be the same part on the left.

The problem is I do not know what it is.

View attachment 102172View attachment 102173

View attachment 102174

I remove the left one and tested it with multimeter in diode mode. It looks like it is an diode because the meter shows value(850) only on one bias testing.

If it is an diode, what number should I use? Any ideas?

Thanks.

 

[yo2550]

Re: Please help me figuring out a missing part in this multi-sim mobile phone

It is **broken link removed**

It's sold out. I am thinking about buying the similar one to get the part form a new one, but not sure if the pcb diagram is the same.

I saved some contacts in the phone memory. That's why I am trying to fix it.