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What the purpose of mesa boost ic in backlight circuit?

So I've been working with backlight recently and can't find a lot of information on mesa boost ic's purpose. For example I have an iPhone 6 plus with no backlight at all. Judging by circuit since there's two diodes and two drivers and two coils and only 1 mesa boost ic, the mesa boost ic could be the culprit. No shorts and have checked all filters.

To my understanding if one half of the screen is dim or black and other is working it's one side of the circuit including diode, coil and driver. If entire screen is out possibly mesa boost?

Again I'm kind of shooting in the dark so any help or insight would be much appreciated. Thanks in advance!

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Are you sure it is "no backlight" and not "no display?"

Is your screen confirmed good?

Put simply, mesa boost is to wake your phone from the home button.

Was the phone previously liquid damaged? Otherwise what happened that made it loose display or backlight?

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No backlight is coming through at all. Normally with no display I would assume filters but because there's no backlight at all I'm assuming ic chip. Guessing right now it's display pmi chestnut ti. No liquid damage as well. When removing cpu shield I noticed two solder blobs, one from left backlight driver and one between a cap and another component.

Correct me if I'm wrong but if it's dim most likely its filter related. If there's backlight but no display on one or both sides its driver/diode or coil related. And if there's no backlight at all coming through possibly chestnut ti ic?

Also tested backlight caps and there's no shorts.

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Anything wrong (blown filter, shorts on caps, short on driver, blown diode, etc) with the backlight circuit can produce a dim screen that'd require a flashlight or something to see what is being displayed on the lcd. If you're getting no display at all that's a different issue.

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Mesa boost drives the metal ring on the home button, it should not be related to backlight.

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Thank you tom. If I can bounce one more question off you. On the 6 plus when there's no backlight at all from your experience is that driver related. Both coil and diode show no physical damage.

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The backlight driver is switched from the LCD pmu chestnut. Chestnut also powers touch driver. 1v8 is the sleep/wake voltage. When you wake the chestnut powers the LCD and there is a short delay to the touch driver. The LCD is primary wake that wakes the backlight and touch. If no lcd then no backlight or touch.

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