No Power and no sign of life.
Can anyone tell me what this capacitor is for and if it is parallel to anything and needed?
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Had a look at the images you uploaded and here's what I got. If I'm reading the picture correctly, this is C8183 which is on an output of the Power Management Chip that takes VCC_MAIN and changes it into PP3V3_S2. This line goes on to the WiFi IC,the touch ICs and the NAND. Which is kind of important. No NAND means no boot at the very least.
So it sounds like this line is short top ground. Unfortunately, it goes quite a few places. As @dadibrokeit mentioned, there's probably a bad capacitor on this line and it will likely function just fine without it. It's not necessarily the one you highlighted. But it might be. There are a few ways you can use to find a short, but I would start by just looking. Sometimes you can tell. There are lots of other caps on that line, so isn't necessarily that one that's bad. (But maybe it is and I overlooked that).
UPDATE: In light of the additional info you provided. Here's some context of how the Power Management chip works because I think learning basic electronics is super important when you're troubleshooting boards. I was about to go off about buck converters and the like but I will save that for a more relevant answer.
The Power Management chip is basically just a hub where many various voltages needed by other board components are generated. That means there could be a dozens of various outputs. It's quite unlikely multiple outputs are bad or short, unless they travel close to each other within the chip, or under the chip. I almost never see bad Power Management chips alone. Especially in the absence of damage to the chip itself.
I mention this because there are many lines that come out of the power management IC that are commonly mistaken as shorted to ground when they are just naturally low resistance. So they might beep in diode mode, or resistance mode if your meter does that.
You said there were many components that tested short around the PMIC, but it would help to know where exactly. Anything in that clump around the initial capacitor you mentioned is all the same line. If the line is short in one place it's short everywhere on that line.I still think a bad cap is your issue.
To find the actual short, you may need to inject voltage into that line directly (so you can generate the necessary energy), or try to provide power through the battery connector. (Won't boot without a battery connected, but it will get Apple logo).
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Right, good answer there is a lot of shorted caps that i tested. Ipad draws 0.050amps of power when plugged with battery connected and without. Im guessing maybe the power IC @flannelist. There isnt any heat singals or anything.
@joshrew .05 Amps is hardly anything in relation to what an iPad normally draws. It might not be enough current to generate a noticeable amount of heat.
I'm going to update my initial answer rather that try to cram everything I want to say into a comment, but I am unlikely to suspect the Power management chip. If you're measuring that the capacitor in your original post is short. That's your problem.
@flannelist correct it is showing shorts on all the caps and also diodes all around the Power IC. Im at a stump for this one also customer doesn't want to spend much over $120 to fix it so im just going with non repairable due to price. I appreciate the feedback and help!
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Hi Josh,
I'm afraid I don't have schematics for your iPad, but let me tag @flannelist and see if by chance they have a set.
Otherwise all I've come up with so far is gloom and doom from repair.wiki.
A2197/A2200 2019 10.2” iPad 7th Gen - Repair Wiki
Problem: No Power. Passes Tristar Tester, no VCC main or secondary voltage shorts, does not boot directly into DFU, will not restore (usually gives Error 4013).
Solution: This device is very notorious for having CPU related issues. The board flexes and tends to disconnect traces under the CPU causing this issue. Reballing the CPU can sometimes fix the issue, but the CPU also can just fail altogether. Seems to be a very common defect for this model.
Update (05/18/23)
Hi JoshR,
Going by the somewhat fuzzy schematic you posted, that cap appears to be primarily a filter to smooth the line its connected to (I can't read the name of the signal on the schematic).
As such, you should be able to pull the cap from the board and see if that allows the board to boot. The cap is supposed to appear as an open circuit to DC voltage but if it's overheating that would indicate that its dielectric has failed and it's providing a direct path to ground on the line it's on. Once you have the cap removed from the circuit it should appear as an open circuit on an ohmmeter.
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That is really good information, i was actually brought this Ipad to try and fix and upon opening the device i noticed that this cap is already missing. The device shows that power is being delivered but absolutely no sign of life. That is why im concerned if this missing cap is the problem.
@joshrew I can't answer with any authority here, but in general capacitors in digital electronics are used to smooth signal lines rather than to pass through AC signals. As such, it's more likely than not that if a capacitor is missing, the circuit will usually still work, at least to a certain extent. But without knowing what this particular cap does, it's impossible to say if that's true or not.
@dadibrokeit looks like it is part of VCC Main U8100 PMIC. I have tested multiple other capacitors and they all test with a short. Im assuming there is a short in the U8100 chip?
Ill post picture above
@dadibrokeit @jioshrew I DO have schematics for this. And a boardview. But not that I can access at the moment. It’ll have to wait until I can get to my home PC, or I have patience for my Windows VM on my Mac (I don’t, lol).
@flannelist thank you for the response i listed the schematics above for the line the cap is on.
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Josh, we're flying blind here. Which capacitor are you talking about? You'll need to show us with a picture or indicate which one on a schematic.
iFixitでの質問に画像を追加する方法
Jerry Wheeler さんによる
@dadibrokeit my apologies thought it uploaded i will submit them
JoshR さんによる