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Released on September 19, 2014, this 4.7" screen iPhone is the smaller version of the iPhone 6 Plus. Identifiable by the model numbers A1549, A1586, and A1589.

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Diode mode shows short. But not drawing current when injecting voltage

Hi i got iphone 6 short on vcc main it shows 006 ohm in diode mode. when injecting 1v voltage. theres no current draw. after remove injecting current wire. short is gone. but resistance slowly decrease until 006 ohm and gives beep sound in continuity mode. please i have no idea.

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The measurement you get in diode mode is not Ohms but Volts. It may seem like it's not important but if you want to understand what the meter is telling you, you have to know what it's actually doing to give you that measurement.

When the multimeter is in diode mode, it is applying a low current (this can vary slightly from one meter to another) across the two probes. Normally a diode operates as a one way valve, if you will, so the meter should read OL when you are reverse-biasing the diode (essentially an open circuit) and whatever the forward voltage drop the diode generates (typically ~.5 - .7V) when you are forward biasing it. You can read more about it here.

The point is when you are measuring an active circuit, one with IC's, you should be measuring some value, typically between .2 and .7V. Comparing this to known good values can help you see inside the IC.

Now if you are seeing 0.006V on VCC_MAIN, then it is probably short circuited and you have to find the short. You can inject voltage to do this but the 1V you used isn't really strong enough to generate much heat and in many cases, not even strong enough to activate the power circuit. You need to ramp that up above 2V and maybe even 3V. The other problem is that all of the current flows through Q1403 so if you try the freeze method (or now IR Camera), this is what will heat up first.

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Thanks minho. I applied 3.8v. But current draw too small on power supply. Below 100mA. No heat detected.


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John zal eeuwig dankbaar zijn.

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