Saltar al contenido principal

iPhone de 4 pulgadas lanzado en marzo de 2016 con especificaciones de hardware similares al 6s. Disponible en Plata, Gris espacial, Oro u Oro rosa con opciones de almacenamiento de 16/64 GB. Modelos A1662 y A1723.

Preguntas 691 Ver todo

u4020 critical to boot?

Good afternoon,

I'm just researching a water damaged iPhone SE that initially had a VCC_Main shorted that was alleviated by removing one cap.

When connecting to power now, it draws 0.43mA / 0.44mA and U4020 LED Driver gets really hot (freeze spray used to detect).

It controls the "LED Driver" and schematics says it is critical. Is it critical for boot? or if we remove this should we be able to artificially use a light and go into the screen layers?

Contestado! View the answer Yo también tengo este problema

Es esta una buena pregunta?

Puntuación 0
Agregar un comentario

Kits de Reparación de Android

Estás a un kit de tu nueva pantalla o batería.

Comprar Ahora

Kits de Reparación de Android

Estás a un kit de tu nueva pantalla o batería.

Comprar Ahora

1 Respuesta

Solución Elegida

Just to confirm, U4020 is not Stockholm but the Backlight Driver IC. A damaged or defective backlight driver doesn’t stop the phone from booting, unless it is pulling down PP_VCC_MAIN. So check VCC_MAIN to see if it is short or or not giving the proper voltage.

Obviously, a missing backlight driver doesn’t affect the boot either.

You should also probe the backlight circuit as if U4020 is hot, then one of the caps may be shorted on the output side.

Fue útil esta respuesta?

Puntuación 3


Thank you Minho, Not sure how I got this confused thinking it is Stockholm, must have had different schematics up or something. Will check the VCC_Main voltage and see

- Por

VCC_Main is low! 2.9V, I will remove this and see if it helps things.

- Por

VCC_Main short up to 3.6V now but still power being drawn is 0.45mA, no obvious signs of heat but removing this chip helped because there was a lot of corrosion, even under it!

Any ideas of probing further with this at all? I really appreciate your help!

- Por

What do you mean by "VCC_Main short up to 3.6V " ?

- Por

Using a multimeter in DC voltage mode VCC_Main is reading at 3.68V, before removing the LED Driver this was a lot lower

- Por

Mostrar 1 comentario más

Agregar un comentario

Añadir tu respuesta

Elliot estará eternamente agradecido.
Ver Estadísticas:

Ultimas 24 horas: 0

Ultimos 7 días: 0

Ultimos 30 días: 0

Todo El Tiempo: 82