Why does an LCD need a reset line?

[gabiz_ro]

Re: Why does an LCD need a reset line?

Or maybe CPU doesn't reach stage when LCD must be on so reset line is low.

[caphair]

Re: Why does an LCD need a reset line?

Or maybe CPU doesn't reach stage when LCD must be on so reset line is low.

What stage?

[gabiz_ro]

Re: Why does an LCD need a reset line?

So if this line is shorted then it's the transistor within the CPU that's gone bad holding it at 0v correct?

I mean power up,resume from standby etc.

Are you sure is shorted?
In many cases when you measure something like that on powered devices is possible that multimeter read in fact C-E or G-S (depending on transistor used) in ON state.
Is more convenient to keep reset low and timed enabled as needed vs let it floated or high and just a pulse when needed.That for devices in stand-by or sleep mode.

Without battery or charger connected is still short on that line?

[caphair]

Re: Why does an LCD need a reset line?

Yes I measured with no power at all in diode mode, red probe on ground and black probe on the reset pin and get 0v.

A known good working board with same measurement done in diode mode reads .432v

Not sure how it shorted or why

[gabiz_ro]

Re: Why does an LCD need a reset line?

Is clear now that is a short on this line.
I suppose LCD was disconnectet too.
Can't look on schematics if there are any other components,like a capacitor,from this to ground.
Just fixed few days ago on 6s draining battery and can't enable touch id.
One little capacitor get shorted.