iPhone 6S won't charge, detects cable.

smilingdog

New member
Hi everyone,

I have an iPhone 6S that is giving me some problems.

When it first landed on my desk it came as not charging. I checked the basic stuff (USB flex, battery, etc.) and determined that since it was not even detecting the cable the Tristar must have been fried, so I replaced it.

After replacing the Tristar the phone was detecting cables but the following behaviour started occurring:

A: When the battery was <0% (black screen with battery sign, phone off) the phone was drawing around 450mA from the USB port and that current must have been used to charge the battery since after a few minutes the phone turned on.
B: As soon as the Apple logo appears the current drawn from the USB port drops to 0 but the phone continues to boot, once booted it displays the lightning logo next to the battery indicator (which is around 2-3%), so it detects the cable and it thinks the battery is charging, but that can not be true since the current draw is 0.
C: When the battery drops to 0%, A happens again, and this repeats, and this happens with a few batteries.

No components are missing from the board (at least I could not find any signs of damage).

I measured the following components and all tested OK.
R2400 measures 100R +/- 1%
C2400 is not shorted
R2311 measures 100R +/- 1%
R2320 measures 29K. This is the only one that is not spot on but it's only ~6% off, so I don't think it is causing this.

TIGRIS_ACTIVE_DIODE did not change when I plugged the cable in so I thought that maybe U2300 was fried, so I replaced it, but still, exactly the same behaviour.

I'm a bit lost right now. I wish I could get the datasheet for U2300 but I don't think it's available publicly.

Any thoughts?

Thanks,
smilingdog
 

larossmann

Administrator
Staff member
voltage on pin1 of R2300(no stuff but should be a pad there to measure on) at the moment it is charging, and the moment it decides to stop charging?
 

smilingdog

New member
voltage on pin1 of R2300(no stuff but should be a pad there to measure on) at the moment it is charging, and the moment it decides to stop charging?

That line is I believe TIGRIS_ACTIVE_DIODE, as I said it did not change regardless of whether the cable was plugged in or not, however I did not measure it when the phone was drawing current from the USB port, I only did it once it was on.

I can't measure that until next week, I'll report back.

What are you thinking?

Thanks Louis. Say hi to Blackberry and Mr Clinton from smilingdog.
 

jessa

New member
You'll save yourself a lot of trouble if you ditch the bad battery and use a good one that has some charge in it.
 

smilingdog

New member
voltage on pin1 of R2300(no stuff but should be a pad there to measure on) at the moment it is charging, and the moment it decides to stop charging?

I just measured that, it's around 3.6v when it's drawing 450mA from the USB port and once the Apple logo appears it drops to 0.

As I said, it's doing the same thing with several batteries, charging connectors, etc. All known good.
 

smilingdog

New member
I don't fully understand that charging circuit. Is Q2300 used just to let the battery power PP_VCC_MAIN? That would explain it being open when the phone is drawing current and closed once it is not charging anymore. Is there no current sensing circuitry for the battery on the 6S?
 

jessa

New member
Post what happens with good batteries--i.e. Charged batteries. Right now the fact that all your data posted is about dead batteries below 0% is a variable.

if your troubleshooting "can this phone charge" then you need to give it a battery that is not dead.

if you are saying "this phone pulls normal charging current on a charged above 30% battery and I am only troubleshooting why it can't charge multiple dead batteries" then say that.
 

smilingdog

New member
Post what happens with good batteries--i.e. Charged batteries. Right now the fact that all your data posted is about dead batteries below 0% is a variable.

if your troubleshooting "can this phone charge" then you need to give it a battery that is not dead.

if you are saying "this phone pulls normal charging current on a charged above 30% battery and I am only troubleshooting why it can't charge multiple dead batteries" then say that.

When I put a charged battery it does what I described in the first post starting from B, just instead of 2-3% it goes from whatever the battery is charged at to dead, and then the cycle starts again.
 

jessa

New member
ok, so the fault is "fake charging" with a known good charged battery, other variables eliminated. Let's start there. You've replaced tristar and then later tigris. My advice would be to replace tristar again. A bad tigris can sometimes kill a tristar. This is a pretty common fault so the chance that it is some zebra is very low. With iPhones there are only a handful of components that can be at fault, most of the circuitry that you are used to from laptops is inherent to the chips themselves. Tristar must give tigris a thumbs up for actual charging to happen. My guess is that tristar is deciding to drop the ovp_en_l line which is the thumbs up for tigris when the phone boots. This is either bad tristar placement or bad tigris killed tristar. Replace tristar again and report back. Stick with a single known good charged battery to keep new variables from entering the picture.
 
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