Motorola XT1049, XT1050, XT1053, XT1055, XT1056 No Turn On Troubleshooting Guide

No Turn on Debug Guide

Objective

This guide is meant to be a step by step troubleshooting procedure for narrowing down the root cause of no turn
on failures.

Instructions

Start on the Main Debug Flow page and follow the procedure. There are links to other sections of the document
that contain helpful information or further debug steps. There are also back arrows on some pages meant to
return to the original debug steps.

Equipment

This guide assumes access to the following equipment:

Multimeter with probes capable of probing 0201 components

-Oscilloscope

-Battery eliminator

-Power supply with current measuring capability

-Factory cable connected to power supply with current measuring capability

-PC with ability to flash software using fastboot and qflash tools

Revisions

This document will be updated and improved as new failures are analyzed. Please send feedback to Rick
Jakubowski at [e-mail].

Revision History

-Document created 6/3/2013, Rick Jakubowski

-Added off/on current and stuck flash mode debug guides, 6/14/2013, Rick Jakubowski/Sanjay Patel

-Added debug steps for units that flash bootloader successfully but don’t power up, 7/10/2013, Rick Jakubowski

-Fixed debug order of turn on sequence, 7/11/2013, Rick Jakubowski

Rick Jakubowski, Sanjay Patel 6/3/2013

Motorola Mobility Inc. Confidential Restricted

Main Debug Flow

Blank phone, Plug

in Factory Cable

Does device

enumerate as

QDLoader under

ports?

yes

no

Does device

power up into

fastboot mode?

yes

Unplug USB cable

Battery current

> 200mA

yes

Retry with battery
power connected

at 3.8V

no

Flash bootloader

nono

Does device power

up in fastboot mode?

yes

Flash full software

image

Successful?

no

Go to no power on

debug flow

Retry with battery
power connected

at 3.8V

Go to high on
current debug

Go to flash failure

debug flow

Allow board to run

through board test, if

board cannot power up

without battery, suspect

PM8921 SMBC issue

yes

Successful?

no

yes

Allow board to run
through board test

Motorola Mobility Inc. Confidential Restricted

No Power On Flow

Attach battery

eliminator to

device, set to 3.8V

Measure off

current

Go to high off current debug

no

Less than

200uA?

yes

Insert USB cable

Battery current

> 60mA

yes

Go to high on
current debug

no

Accessory
current >=

100mA

If unit failed for

WAIT_FOR_FASTBOOT
_INTERFACE_ARRIVAL

Replace MSM/

DDR

no

Probe PS_HOLD

with O-Scope

Constant 1.8V?

yes

Go to enumeration

debug

Alternates

no

Go to Enumeration

between 1.8V

and 0V?

Make sure

battery

attached

no

Debug

no

Battery current

> 1mA

yes

Go to Power Up

Sequence Debug

Motorola Mobility Inc. Confidential Restricted

The following lists nets to probe and their expected voltage. Measure in the following order. If a voltage is more than 100mV different,

there is a failure on that node. Check all parts on the node for process damage, xray IC balls, and take resistance measurement to look

Power up Sequence Flow

for a short. Also take diode drop measurement with multimeter.

VREG_S1 =

1.275V?

VREG_L24 =

1.05V?

VREG_S3 =

1.05V?

VREG_S4 =

1.8V?

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

VREG_L7 =

2.95V?

VREG_L3 =

3.075V?

VREG_L5 =

2.95V?

VREG_XO =

1.8V?

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

VREG_L25 =

1.25V?

VREG_L1 =

1.05V?

VREG_L4 =

1.8V?

VREG_L6 =

2.95V?

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

PON_RESET_

N = 1.8V?

Check resistance and diode

drop to ground, compare

with good board. Inspect all

components on net

Motorola Mobility Inc. Confidential Restricted

High Off Current Debug Procedure

The debug technique for finding the defect causing high off current involves measuring the voltage drop between two
points using a multimeter. The copper routing of the pcb trace has a resistance which will cause a voltage drop
between two points along the same trace according to V = IR where I is the current going through the trace and R is the
resistance of the trace between the two points being probed. If the current is in the uA range then a precision
instrument will be needed that can measure voltage of less than 10uV. If the current is in the several mA range then a
less precise instrument can be used. There is a graphic showing the B_PLUS and BATT_PLUS routing of the board. Pick
two points to measure while a battery is attached and the high off current is being drawn from the battery. Compare
to a good board to isolate the location of the extra current.

B+ Routing BATT+ Routing

The following lists nets to probe for resistance. Measure resistance from net to ground plane and compare to normal board. Note

extremely low resistance. Also measure diode drop and compare to normal board.

Power up Sequence Flow

Inspect

VREG_L5 =

low Z?

VREG_L3 =

low Z?

Inspect Routing and

Components

Inspect Routing and

Components

VREG_S4 =

low Z?

VREG_S3 =

low Z?

VREG_L24 =

low Z?

VREG_S1 =

low Z?

Inspect Routing and

Components

Inspect Routing and

Components

Inspect Routing and

Components

Inspect Routing and

Components

VREG_L7 =

low Z?

VREG_L6 =

low Z?

VREG_L4 =

low Z?

VREG_L1 =

low Z?

VREG_L25 =

low Z?

Inspect Routing and

Components

Inspect Routing and

Components

Inspect Routing and

Components

Inspect Routing and

Components

Inspect Routing and

Components

Motorola Mobility Inc. Confidential Restricted

Flash Failure Flow

Plug in factory

cable connected to

power supply to

monitor current

Run qflash to

blank flash board

Copy text from

qflash

Bootloader

flash

successful?

Go to stuck qflash

debug

Match qflash1? Match qflash3? Match qflash2?

yes yes yes

Suspect MSM

defect or process

issue, analysis

pending

no no

Suspect MSM

defect or process

issue, analysis

pending

Suspect eMMC

defect or process

issue, analysis

pending

Motorola Mobility Inc. Confidential Restricted

Enumeration failure flow

Inspect USB

connector

Inspect D+/D- filter

Inspect ESD and

bypass parts

Motorola Mobility Inc. Confidential Restricted

Probe point locations

PS_HOLD

USB_Components

FORCE_FLASH

Motorola Mobility Inc. Confidential Restricted

Probe point locations

PON_RESET_N

Motorola Mobility Inc. Confidential Restricted