Iphone 6s Plus no touch no fingerprints

[Juan Carlos]

Hi friends I have one Iphone 6s plus who have the touch not working and the fingerprints not work either came from other repair shop Initially these is what I found FL4291 blowout that line suppose to have 25 v but in order fix these problem I try to see where these voltage came from but I can’t find it




I know I need to make the touch work these voltage

And all those is present

pp5v7 MESON_AVDDH_CONN

PN5v7 LCM_MESON_AVDDN_CONN

PP1V8_TOUCH_CONN

AP_TO_LCM_RESET_CONN_L




but Is hard get these voltage PP5V1_TOUCH_VDDH_CONN on C4003 Any advance to read these voltage in other area and any other advice because I don’t know what other area I have to check if those voltage is present

Thanks for the help

[Jessa_the_Professa]

You have a lot going on with this device.
Pick a problem that you want to solve first---let's say "no touch" and work on that.

Questions for you:
Do you think the blown filter FL4291 has anything to do with touch?

Do you think the missing component (look it up) by the fcam connector has anything to do with touch, if not, what function might it be important for, if any?


You have started checking to see if you have touch power voltages present, that is a fine strategy. However, touch POWER is only half of the picture. In order to have touch function you also need Touch DATA--this means all the lines that are sensors, and communication lines, and resets, and enables, switches, controllers, modulators, effectors, etc....All of THOSE lines that are ones and zeros and not just a straight power voltage, they all need to be present, correct, and working.

So how can you figure out if a data line is working or not? We can use an oscilloscope to see the ones and zeros, or we can just see if the line is structurally sound, i.e. is it open or short to ground. Do that using diode mode, red probe on ground, black probe on the line and see whether you have a value that doesn't match a known good.

My next step on this one for sure would be diode mode comparisons of BOTH the touch POWER and touch DATA lines. (Hint: the way these usually fail is a missing component on a data line from pry damage or an open line at CPU on a data line from attaching the wrong connector due to not repositioning them in correct order.)