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I removed the capacitor on the 5v7 (i think that is what it's called) line for the display, and it came right back on! But I have a question, do I need to put a new capacitor on there? Or will the phone be ok?
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The caps you removed are C4200 & C4201 on the PP5V7_LCM_AVDDH rail.
Capacitors fundamentally do one thing, that is store a charge. They have some amazing properties, which means you can use them for different purposes. In the context of an iDevice, they are mainly used for noise filtering and decoupling (bypassing).
You’ll notice that sometimes there is more than one capacitor, mostly different values, in parallel (like C4203 & C4204 above). That is to optimize the frequency response of the decoupling. You also see multiple capacitors in parallel with the same value. That is done to get a much larger capacitance without having to use a big-ass cap when vertical real estate is at a premium, like on an iPhone.
Technically speaking, you don't need to replace them but consider that they were put there for a reason by the Apple engineers.
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God, when you speak it's like reading the bible! Very insightful. I will let the customer know this information, mainy this was data recovery, so I told them hurry up, get the data, and if they want the same phone I could get a new logic board.
Thanks...but a deity I am not :>).
I often see these questions about whether a cap should be replaced or not. The fact of the matter is that most of them don't need to be replaced to get the data off and most of them don't even need to be replaced to make a working phone.
The caps decouple, as I mentioned above but they also act as a reserve of "juice" for instantaneous power demands. This is especially true for the CPU, which is why there are so many caps around (and underneath) it. Apple is building hundreds of millions of phones so they need to optimize the design so that *everyone* is happy with the performance and that there are no weird, unexplainable glitches. They are playing a numbers game. For a one off phone, you probably wouldn't notice the difference.
However, from a professional repair perspective, I always encourage people to replace parts. Overkill perhaps but thats what distinguishes professional from "fly-by-night" techs IMHO.
Yes! And he is an employee for a construction company, his phone came in so damaged I even thought maybe he go water on it and didn't know and that's what caused the demise, THERE WAS A HOLE IN THE SCREEN!
I want them to be pleased with my service and since this is literally one of my first non-practice Micro soldering jobs I am just glad it decided to come back on.
Thanks for your help!
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Capacitors in parallel multiply the current delivery capacity while the voltage remains the same. In short, the capacitor removed should be replaced. The reason is not replacing this capacitor will put additional stress on the other capacitors and the display may have visual effects due to power fluctuations. As an electrical engineer, I frequently put surface mount capacitors in parallel to save space and to provide smooth current flow. These capacitors are rated at 6.3 volts which is very close to the rated power rail and may be related to the failure of this capacitor. I would replace this capacitor and potentially the others with a 2.2uF 10volt version that has the same physical size (0603 metric). Here is a link to Digikey to the component replacement I recommend: https://www.digikey.com/product-detail/e...
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