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**Jessa_the_Professa** · 12-03-2017, 01:12 AM

I'm known for being very direct with people. So here's the deal---I don't value 88 cents/day forum membership to put up with ANY kind of forum whining. I will answer questions when have time to do so. I will miss some questions entirely. I will offend people with my answers. I will piss people off with my insistence that folks put a lot of thinking into these problems. I will not know the answers to many questions. I will be wrong and give bad advice at times. When kids get sick or I have to travel, I may not answer questions at all for a few days now and then. You ask "what can we expect from you for your 88cents/day service?" The answer is that I will answer your questions when I feel like it, period. That's the deal. I doubt that you're going to be happy with those terms since you're making whiney posts 48 hours into your membership on a weekend---hence I refunded you. You are welcome to go join any other forum out there that might be a better fit.

I do appreciate that you've clearly put thought into your problem, and I see that you've made other detailed posts in the spirit of helping others put thought into their problems as well and I certainly want to build that kind of community on this forum. I can see that if you can adjust your expectations of this forum to be more in line with the above, then I'm willing to give it another try. I will ask Louis to unban your IP address and you can re-subscribe.

I will answer your question anyway while I'm here. Also, do keep in mind that if you purchase your chips from https://store.rossmanngroup.com , I am willing to ignore any and all of the above and make an exception just for you as a thank you for your chip purchases.

**Jessa_the_Professa** · 12-03-2017, 01:27 AM

Originally posted by Sly View Post

Hi,
I have now encountered a problem that I can't resolve.

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Info & Original Fault

Model:iPhone 5s

Symptoms: Would not charge the battery once it was fully discharged, but would charge an already charged battery.

Repair: Replaced the 1610A1 with 1610A2

Result: The phone charged perfectly, but the phone was stuck in a bootloop

Attempt to fix the bootloop:
*Replaced the battery,
*Update the iOS, It got stuck during process.
*Restore. It got stuck during process.

*Replaced the new 1610A2 with an 1610A1 from a working device*
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New Problem

Wont Charge, Wont Boot:
*No more current draw reading from the usb am meter.
*Wont Boot

Much Shame:
*Tristar chip was not soldered on properly,
*Q2 had shifted

so I've reinstalled both of them properly.

Result: Wont Charge, Wont Boot

*USB amp meter:
Battery disconnected, 0A draw
Battery is connected, 0.24A draw

*DC Power supply:
Before prompt to boot, 0A draw
After boot, steady 0.019A
*iTune wont recognize it

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Where I'm stuck

Troubleshooting:
*Compared voltage drop across all pins of J7

*Check 5V0_USB_Prot line while the phone is connected = 5V

*Check the voltage on BATT_VCC_CONN while charging:
Battery connected = slightly higher than battery voltage (which justifies the 0.24A draw from USB amp meter disclosed above)
Battery disconnected = 0V
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New Objective (Why wont it boot)

Elimination Process:

Rule out new components:
*Removed tristar and Q2 = No Boot +same current draw from DCPS after prompt to boot.
(Same model of known working board did boot without those components)

Is PMIC Working:
*Measured some output voltages after prompting the phone to boot. Still with a constant 0.019A draw from DCPS
PP3V0_SDRAM = 3V
PP1V8_SDRAM = 1.8V
PP_VCC_MAIN. = V_BATT

It apears ok

Bad data line:
*Checked voltage drops on all the pins of the board for U2.

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What now

Theories:
*I've affected a data line by sending higher voltage to it when Tristar was shifted (Seems likely)
*I've knocked a component off, or moved one on the edge of the board while removing the shield ( I've check for this, seems ok)
*U21 (Audio Codec) has a lot of underfill around it, and it got over heated. (It was covered with a heat sync, and no solder balls where detected)

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I'm leaning towards looking more into the data lines again, but I'm hoping you might you have some insight.

Thank you

This is very well put and clear.
From the beginning--this was a classic tristar presentation, so changing tristar was the right move. You should stock one tristar chip for all 1610 devices---the 610A3B chip--and always use new, never reballed chips for tristar jobs.

After your first tristar job, it is not uncommon to have data corruption---it is easy for tristar faults to corrupt data because it sits on lines that are general communication for CPU. Making the guess that the bootloop was software related after tristar was reasonable as is often the case for dead phones due to tristar faults. However the device HAD been booting before the tristar change so this changes the story a bit. You have the added variable here of new batteries---new batteries are often defective out of the box with faults on the gas gauge lines, and it is also common to get gas gauge faults during any repair on a 5s due to knocking off gas gauge filter. When you say "stuck in a boot loop" this could point to a gas gauge fault boot loop. A phone will not restore with a bad gas gauge.

The best thing to do at that point would be to look for gas gauge filter on the board and make sure it is intact, and to attempt restore with a KNOWN GOOD and not just new battery. Then report what error you got with iTunes update/restore since sometimes the error can give us a clue.

The next step of a mal-placed tristar is a big complication for the exact reasons that you suggest. The CPU is extremely sensitive to wrong voltages. The CPU is designed to be a low impedance device, meaning tiny sub 1volt voltages generate massive current in the CPU. If we accidentally send MORE than one volt--by bridging a 3v or 5v line into a CPU line---that can easily electrically destroy the CPU.

I think that you analysis of the current problem is correct---one our "highly likely" differential diagnosis from what we know about this phone is that there may be CPU damage from a badly placed tristar.
I asked if the DCPS current draw was 0 before prompt to boot to either confirm or rule out that this is heat at audio ic---which goes lower on the priority list if there are no signs of heat and no current draw before prompt to boot.

The other thing that can also go on the "highly likely" possibility list is overheating the baseband CPU--you can check for signs of heat. You can also check for missing filters/resistors under the sticker by the dock.

If this phone was in front of me, I'd change tristar again using a new 610A3B chip, assuming no signs of heat at baseband CPU, and I'd jump across Q2 just to rule that out, and I'd prompt to boot with both usb an with power button to see if the result is the same or different. If I continued to get normal power line readings and low overall current readings, I'd attempt to put the phone in DFU to see if it was recognized by iTunes---if not, at that point I'd conclude 'likelihood of internal CPU damage is too high to put more time into it."

**Sly** · 12-03-2017, 02:09 AM

Thank you for taking the time to answer back. I clearly see what you're saying.

I've started my own business of electronic repairs 1 year ago, and I'm in the middle of moving to a new location, expending my products & services, and rebranding. The stress levels are high these days, and that post was out of character. That is why I posted it, then felt remorse because I can only image the workload you must of already had before even introducing this platform, so I edited it, then I deleted it...

You've given me and many others all the tools and resources for free via youtube to empower us to do what everyone said we could not. I've went from being a glorify screen replacer employee to a being business owner with the ability to do complex repairs in this last year alone. From not knowing how to re-flow a simple pin of a broken charging port, to repairing multi-problem motherboards that other bigger shop declared dead, and successfully recovered hundreds of pictures of babies,weddings, and important memories.

That is all thanks to you,others in the community, and lots of hard work.

I hope to be an active member of this new wave you're creating in the industry, and offer you a big old Canadian apology for my whiney behavior!

Have a yourself a good weekend.

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iPhone 5s Tristar Replacement Gone Bad

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