Water damaged iPhone 6 100mA draw

[Jak88uk]

Hi,
I’m new to this forum and looking for some help.. I have a water damaged iPhone 6 that won’t turn on. I have put it through the ultra sonic cleaner. After removing all shields off the board I found a vcc_main short, and c5202_rf looked horrible so I removed that cap and now the short has been relived from vcc_main.

When I connect the phone to dc supply I have a 100mA draw before prompt to boot.

Can anyone help on where to look next and what I should be checking? what would be causing the 100ma draw before prompt? Is there any common IC’s?


Thank you in advance.
Jack

[Jessa_the_Professa]

Hi Jack
what makes you think you have cleared your vccmain short, rather than reduced a full short from c5202_rf to a partial short on main somewhere else?

if you have a partial short you will not be able to detect it using continuity mode with the multimeter, this is why we use diode mode—red probe on ground black on main and you need to get 0.33 ish.

what is your diode mode reading on main?

[Jak88uk]

Thank you for your quick reply jessa! :-)
It seems like I am still learning the basics here. It does seem that vcc_main still does have a full short, the diode reading is 0.01, so I’m guessing that is a full short.
Regarding the next steps for looking what is still shorting out vcc_main, would I need to check zxw and see what caps are link to vcc_main then inspected the board to see if any are bad? And then check the caps to see if there shorted to ground? Or is the better way to inject voltage into the board?

As you can tell I’m a newbie, but hoping to learn.

Thankyou again.

[Jak88uk]

Hi, just an update I have been probing around vcc_main and come across a couple of nasty caps which I have now removed.. my reading in diode mode is now .304 does that sound about right for vcc_main?
Thanks

[eDigitCom]

It sounds good to me Jak88uk

Some meters can give slightly different readings then others depending on the quality of the meter

[Jak88uk]

eDigitCom Thank you :-). Good to know vcc_main doesn’t have a short anymore. Connecting it up to dc supply still shows a 100mA draw before prompt, where should I be looking next? Any certain lines that cause 100mA draw?
Thanks

[eDigitCom]

I leave that one to Jessa

[Jessa_the_Professa]

Great—you’ve brought Main up to 0.3 which is only slightly low. Remember that shorts can be caused by caps AND chips. It sounds like this is a rice phone—a wet phone that had charger voltage running though it and electroplating a lot of vccmain. Those can never be a phone again because you will have mud under every non-underfilled chip in any spot where water went.

You need to find the source of your 100mA leak. Show us some pictures of the worst water damaged areas. Check backlight anode line and speaker amp boost lines for short

[Jak88uk]

Hi Jessa, thank you for your support so far, I was probing around after I had sorted the VCC_main sort out, and I noticed that I had problems with many caps that link to the BaseBand PMU ( PM8019) chip. some of these caps are C3211_RF, C3213_RF, which I believe are PP_LD010 and PP_LD012 that are sorted. I'm not too sure if I'm right in my next steps with removing the caps as they looked corroded anyway did not relived the short. As I knew these linked to the PM8019 IC Chip, I went ahead and removed the chip. Once the chip was removed it was very corroded under the chip, so I'm guessing that would need cleaning and reballing anyway. With the PM8019 Chip removed I still have a short on the lines that link with Baseband PMU. Before I continue on am i way off, or was my thought trail correct? Also I'm guessing the phone needs Baseband PMU to boot?
I will check backlight anode and speaker amp boost lines for shorts aswel and get back to you with my results.

Thanks

[Jak88uk]

So another update when I now plug the phone into dc supply I have no short before prompt to boot. When I boot the phone the dc supply shows it starting to boot goes to 0.28 0.34 0.40 then shorts out? Any advice on this too? Thanks

[Sly]

Hi Jak,

So, good job so far with the progress made.


Couple of questions:

1.What do you mean by "dc supply shows it starting to boot goes to 0.28 0.34 0.40 then shorts out?" ?Does the numbers keep rising? Does it stops?

2.What lines are you saying that they are still shorted "With the PM8019 Chip removed I still have a short on the lines that link with Baseband PMU" Watch out for data lines going to CPU (AP ****** *****) those are usually very low resistance lines, and they will test beep in continuity mode which is normal.

3.Can you reference the PM8019 with the U**** number usually found in ZXW?

4.After remove the PM8019 chip you mentioned that the phone did not draw .100A on DCPS, but what is the measurement on VCC_main now that this chip is removed? ( like Jessa said 0.3 is still a bit low, it would usually mean a partial short. Often caps will generate full shorts to ground (NOT ALWAYS), and shorts under IC caused by corrosion will often be partial shorts, since they are only going into an other line with a different resistant, and that is not ground)
.
5. Is this repair for data, or functionality? From the seems of it, your starting to get yourself into a large repair with many potential issues. This is the time I would usually contact the customer and explain the state of the phone, and quote for data only. No point putting a bunch of hrs on a phone that might have too many IC with muddy pads under it, you'll never see the end of it for functionality.