EivoTech Laptop & Mobile Repair Master Course

Advanced Extension — Mobile Part 38

Final Mobile Repair Technician Exam + Practical Diagnostic Assessment

Final Assessment: Basic se Advanced Smartphone Motherboard Diagnosis

Ye exam sirf ye check nahi karega ke aapko components ke naam yaad hain ya nahi.

Iska real goal hai:

KYA AAP FAULT KO SYSTEMATICALLY DIAGNOSE KAR SAKTE HO?

Final diagnostic formula:

SYMPTOM → HISTORY → BLOCK → FIRST TEST → LAST GOOD → FIRST MISSING → CONFIRMATION → ROOT CAUSE

Restart/cycling mein:

TRIGGER → FIRST FALLING POINT → ROOT CAUSE

Exam Instructions

Rule 1

Answers guess nahi karne.

Rule 2

Har practical case mein diagnostic sequence likhna hai.

Rule 3

“PMIC bad”, “CPU bad”, “UFS bad” jaisa direct answer tab tak complete nahi jab tak supporting evidence na likho.

Rule 4

Jahan possible ho:

First test
Last Good
First Missing
Confirmation test

likho.

Rule 5

Battery/security/data safety rules follow karne hain.

Exam Structure

Section A

Foundation + Architecture

Section B

Multimeter + Components

Section C

Power + No-Power

Section D

Boot + Storage

Section E

Charging

Section F

Display + Touch

Section G

Audio + Camera + Sensors

Section H

Wireless + Cellular RF

Section I

Battery Drain + Heating

Section J

Schematic + Oscilloscope

Section K

BGA + Sandwich + Special Devices

Section L

Advanced Practical Cases

SECTION A — Smartphone Architecture

Question 1

Smartphone motherboard ka complete basic power-to-boot sequence likho.

Question 2

PMIC ka main role kya hai?

Minimum 5 functions likho.

Question 3

SoC aur simple CPU mein kya difference hai?

Question 4

Modern SoC ke andar kam az kam 6 major blocks ke naam likho.

Question 5

CPU/SoC boot karne ke liye basic 5 requirements kya hain?

Question 6

RAM aur UFS/eMMC/NAND ka difference explain karo.

Question 7

Boot ROM kya hota hai aur kahan located hota hai?

Question 8

Android boot sequence:

Boot ROM se Android OS tak sequence likho.

Question 9

iPhone boot sequence:

Battery se iOS tak simplified sequence likho.

Question 10

No Power aur No Boot mein exact difference kya hai?

Question 11

No Boot aur No Display mein difference kya hai?

Question 12

Logo appear hone se technician ko kaun se major clues milte hain?

Question 13

Always-On rail aur switched rail mein difference explain karo.

Question 14

Rail ka 0V reading kab normal ho sakta hai?

Question 15

Power-state-aware measurement kya hoti hai?

SECTION B — Multimeter + Component Testing

Question 16

Resistance mode powered board par kyun normally use nahi karni chahiye?

Question 17

Continuity beep ko confirmed short kyun nahi keh sakte?

Question 18

CPU VCORE rail par very low resistance milti hai.

Kya direct CPU short conclude karoge?

Reason explain karo.

Question 19

Diode mode ka smartphone motherboard repair mein best use kya hai?

Question 20

Known-good diode comparison ke liye same:

Model
Meter polarity
Test condition

kyun useful hain?

Question 21

Ek rail ke 20 capacitors continuity beep de rahe hain.

Kya 20 capacitors shorted hain?

Diagnostic process likho.

Question 22

Zero-ohm resistor ka circuit mein role kya ho sakta hai?

Question 23

Pull-up resistor kya karta hai?

I2C example ke saath explain karo.

Question 24

Current-sense resistor ko bypass kyun nahi karna chahiye?

Question 25

Ferrite bead aur normal power coil mein basic functional difference kya hai?

Question 26

Ferrite bead par continuity beep normal kyun ho sakti hai?

Question 27

Fuse open mile to next check kya hona chahiye?

Question 28

Fuse ko bridge karna wrong repair kyun hai?

Question 29

MOSFET diagnosis ka master formula likho.

Question 30

Input MOSFET:

Input voltage good.

Gate/control good.

Output missing.

Downstream resistance normal.

Aapka next diagnostic direction kya hoga?

Question 31

LDO ka formula likho.

Question 32

Buck regulator ka simplified diagnostic formula likho.

Question 33

VIN good.

EN missing.

OUT missing.

Kya regulator replace karna chahiye?

Explain.

Question 34

VIN good.

EN good.

Output missing.

Output rail resistance normal.

Is situation mein kya suspect stronger hota hai?

Question 35

Crystal ko simple continuity mode se healthy prove kyun nahi kar sakte?

SECTION C — No-Power + PMIC

Question 36

Completely dead phone ka master diagnostic sequence likho.

Question 37

Known-good battery test no-power diagnosis mein important kyun hai?

Question 38

Main battery rail missing hai.

PMIC se pehle kin stages ko inspect karoge?

Question 39

Main rail present.

PMIC input present.

Always-on rails absent.

Aapka diagnostic direction kya hai?

Question 40

Always-on rail absent aur us rail ki resistance very low hai.

PMIC replace karne se pehle kya karoge?

Question 41

Standby rails good.

Power-button press par power-key signal change nahi hota.

Likely diagnostic block kaunsa hai?

Question 42

Power-key signal correct change karta hai.

Lekin startup rails appear nahi hoti.

Kis stage ko investigate karoge?

Question 43

Startup rails briefly appear aur phir disappear.

Is case mein sabse important concept kya hai?

Question 44

First Missing aur First Falling mein difference explain karo.

Question 45

PMIC hot hai.

Kya PMIC automatically faulty hai?

Kam az kam 3 alternative explanations likho.

SECTION D — Boot Loop + RAM + Storage

Question 46

Logo-loop phone mein first 5 checks kya hone chahiye?

Question 47

Phone recovery mode mein stable hai lekin normal OS boot loop karta hai.

Is se kya clues milte hain?

Question 48

Recovery mode bhi restart karta hai.

Hardware suspicion kyun increase hoti hai?

Question 49

UFS diagnosis ka master formula likho.

Question 50

UFS rail missing hai.

Kya UFS chip bad conclude karoge?

Explain.

Question 51

UFS power/reset/clock correct hain.

Official restore repeated same stage par fail hota hai.

Cable/PC/software/power ruled out.

Ab kis direction ka suspicion strong hota hai?

Question 52

Ek flashing error aate hi UFS dead kehna wrong kyun hai?

Question 53

RAM fault aur storage fault symptoms overlap kyun kar sakte hain?

Question 54

Boot loop sirf new camera module connect karne ke baad start hota hai.

Camera disconnect karne se phone stable.

Root-cause direction kya hai?

Question 55

Side-key power signal permanently active-low hai.

Phone repeated restart karta hai.

Kis part ko first isolate karoge?

SECTION E — Charging System

Question 56

Charging system ka complete source-to-battery master formula likho.

Question 57

No-charging phone par motherboard open karne se pehle kin external cheezon ko test karna hai?

Question 58

VBUS port par present hai.

Protection IC ke input par present hai.

Output absent.

Downstream resistance normal.

Diagnostic direction?

Question 59

Protection output absent hai aur downstream hard short hai.

Protection IC ko faulty kehna kyun jaldi hoga?

Question 60

USB-C phone ek cable orientation mein charge karta hai aur doosri mein nahi.

Strong suspect area kaunsa hai?

Question 61

CC1 aur CC2 ka purpose kya hai?

Question 62

Normal charging works lekin fast charging nahi.

Diagnostic order likho.

Question 63

Charging icon aa raha hai lekin battery percentage increase nahi hoti.

Kam az kam 5 possible reasons likho.

Question 64

Phone wired charging se dead hai lekin wireless charging works.

Kis path ko diagnose karna chahiye?

Question 65

Phone charge hota hai but PC detect nahi karta.

Power path ya data path?

Explain.

Question 66

PC detect karta hai lekin battery charge nahi hoti.

Kis subsystem ki direction strong hai?

Question 67

Battery temperature reading invalid hai.

Charging par kya effect aa sakta hai?

Question 68

Damaged/swollen lithium battery ke saath technician ko kya karna chahiye?

Question 69

Battery cell ko direct charge ya BMS bypass kyun nahi karna chahiye?

Question 70

Fast charging ko test karte hue manually higher USB-C PD voltage force karna wrong kyun hai?

SECTION F — Display + Touch

Question 71

Black-screen phone ko no-power kehne se pehle boot kaise prove karoge?

Question 72

LCD aur OLED mein backlight difference explain karo.

Question 73

LCD black hai but flashlight se faint image visible.

Strong direction kya hai?

Question 74

LCD backlight master formula likho.

Question 75

OLED black screen ka master diagnostic flow likho.

Question 76

Known-good display bhi black hai.

Panel power missing.

Next direction kya hai?

Question 77

Display rails good hain.

Reset stuck low hai.

Kya MIPI ko first suspect karoge?

Explain.

Question 78

Vertical green line after drop.

Known-good display perfect.

Root cause?

Question 79

Touch completely dead.

Image perfect.

Known-good screen same fault.

Touch power good.

SDA stuck low.

Screen disconnect karne ke baad SDA normal.

Likely root-cause direction?

Question 80

Partial touch dead hone par digitizer/panel stronger suspect kyun hota hai?

Question 81

Ghost touch sirf charging ke waqt hota hai.

First comparison test kya hona chahiye?

Question 82

MIPI high-speed lines par random long jumper kyun avoid karna chahiye?

SECTION G — Audio + Camera + Sensors

Question 83

Speaker diagnosis ka master formula likho.

Question 84

Main speaker dead hai.

Earpiece, mic aur Bluetooth audio normal.

Known-good speaker same.

Amp VIN/enable/audio bus good.

Strong direction?

Question 85

Speaker output BTL/Class-D ho to scope safety ka important rule kya hai?

Question 86

Digital MEMS mic diagnosis ka formula likho.

Question 87

One mic dead aur all mics dead mein diagnostic difference explain karo.

Question 88

Bottom mic charging sub-board par hai.

Charging board replace karne ke baad call mic dead.

First suspect?

Question 89

Camera master diagnostic formula likho.

Question 90

One rear camera dead hai, baqi cameras work.

First diagnostic approach?

Question 91

All cameras dead hain.

Camera PMIC VIN present hai.

All outputs missing hain.

Enable/control absent.

Root direction?

Question 92

Camera power/reset/I2C good.

MCLK missing.

Kis stage ko diagnose karoge?

Question 93

Camera open karte hi phone restart karta hai.

Known-good battery stable.

Known-good camera fixes.

Root cause?

Question 94

Camera after drop continuously shake karti hai.

Known-good camera stable.

Likely issue?

Question 95

Sensor diagnosis ka master formula likho.

Question 96

Multiple sensors dead aur shared SDA stuck low.

Ek sensor flex disconnect karne par bus normal.

Root cause direction?

Question 97

Proximity sensor electrically good hai lekin screen replacement ke baad calls par screen wrong behave karti hai.

Physical causes kya ho sakte hain?

SECTION H — Wi-Fi + Bluetooth + GPS + NFC + Cellular

Question 98

Wi-Fi greyed aur weak Wi-Fi mein diagnostic difference explain karo.

Question 99

Wi-Fi greyed + Bluetooth unavailable.

First common blocks kaun se check karoge?

Question 100

Wi-Fi ON hai but router sirf 1 meter ke andar milta hai.

Strong direction?

Question 101

2.4 GHz works but 5 GHz completely dead.

Kis type ka fault possible hai?

Question 102

Wi-Fi/Bluetooth master formula likho.

Question 103

GPS indoor test mein no lock.

Kya GPS hardware fault conclude karoge?

Explain.

Question 104

GPS proper outdoor test ka purpose kya hai?

Question 105

GPS position correct hai but maps arrow wrong direction.

GPS ya magnetometer?

Question 106

NFC toggle works but tags detect nahi hote after back-cover repair.

First inspect kya karoge?

Question 107

NFC + wireless charging dono ek saath rear repair ke baad dead.

Strong common cause?

Question 108

No SIM aur No Service ka difference explain karo.

Question 109

No SIM master formula likho.

Question 110

SIM VCC, reset aur clock present.

SIM data line abnormal low.

Possible path?

Question 111

SIM detected.

Baseband info present.

Manual network search mein operators nahi milte.

Known-good phone same location mein operators find karta hai.

Strong direction?

Question 112

Manual search operators find karta hai but phone register nahi karta.

Receive ya transmit/account side?

Explain.

Question 113

Weak signal after frame replacement.

First 4 physical checks kya honge?

Question 114

Baseband/modem information itself missing hai.

Antenna se pehle kis sequence ko check karoge?

Question 115

IMEI/device identity ke repair mein professional security rule kya hai?

Question 116

4G works but 5G missing.

Hardware se pehle kin 4 external conditions ko confirm karna hai?

SECTION I — Battery Drain + Heating + Shutdown

Question 117

Battery drain master formula likho.

Question 118

Standby drain aur active-use drain ka difference kya hai?

Question 119

Battery 30% par phone off ho jata hai.

First test?

Question 120

Battery health software 90% show karti hai lekin known-good battery se shutdown fix hota hai.

Is se kya lesson milta hai?

Question 121

Airplane mode battery drain ko dramatically improve karta hai.

Kis subsystem ki direction strong hai?

Question 122

Phone idle mein warm hai.

Airplane mode se koi difference nahi.

Software background usage bhi normal.

Next direction?

Question 123

Short aur leakage mein difference explain karo.

Question 124

PMIC hottest component hai.

Why is that not enough to replace PMIC?

Question 125

Phone only camera use par shutdown karta hai.

Known-good battery se same.

First subsystem-specific checks?

Question 126

Phone only cellular call par restart karta hai.

Known-good battery fixes.

Root cause?

Question 127

Known-good battery same fault.

RF supply collapses first.

Root direction?

SECTION J — Schematic + BoardView + Scope

Question 128

Schematic aur BoardView ka difference explain karo.

Question 129

Reference designators ka meaning likho:

R = ?

C = ?

L = ?

U = ?

Q = ?

D = ?

F = ?

J = ?

Question 130

Last Good → First Missing method example ke saath explain karo.

Question 131

Regulator output missing hai.

Schematic se diagnostic path kaise trace karoge?

Question 132

Oscilloscope multimeter se kab better hota hai?

Kam az kam 5 examples.

Question 133

Multimeter rail par low unstable voltage show karta hai.

Scope par rail correct level tak briefly rise karke collapse karti hai.

Is se kya clue milta hai?

Question 134

Enable first drops, phir output rail girti hai.

Upstream ya downstream direction?

Question 135

Output rail collapses while enable remains active.

Direction?

Question 136

I2C activity scope par nazar aa rahi hai.

Kya iska matlab data 100% correct hai?

Question 137

Normal oscilloscope se actual Wi-Fi/cellular GHz RF fully diagnose kyun nahi hoti?

SECTION K — BGA + Sandwich + Foldable/Tablet

Question 138

BGA ka full form kya hai?

Question 139

BGA ko last-stage suspect kyun rakhna chahiye?

Question 140

Random reflow ko diagnosis kyun nahi keh sakte?

Question 141

Heat se behavior temporarily change ho jaye to kya BGA confirm ho gaya?

Explain.

Question 142

UFS BGA ko suspect karne se pehle kaun se prerequisites prove karoge?

Question 143

No Service phone mein baseband info present aur signal weak hai.

Baseband BGA ya antenna/RF first?

Question 144

Wi-Fi weak hai but toggle and Bluetooth digital functions normal.

Wi-Fi BGA ya RF first?

Question 145

Sandwich/interposer fault ko suspect karne ke strong clues kya hain?

Question 146

Hard drop ke baad No Service aaya.

Board separate karne se pehle kya-kya check karoge?

Question 147

Foldable phone inner display dead hai but outer display works.

Diagnostic block?

Question 148

Foldable phone sirf half-fold position par restart karta hai.

Strong suspect area?

Question 149

Dual-battery device mein one battery not detected.

Kin lines/systems ko check karoge?

Question 150

Dual battery packs ko manually parallel/direct-charge kyun nahi karna chahiye?

Question 151

Tablet finger touch works but stylus dead.

Kis subsystem ko separately diagnose karna hai?

Question 152

Tablet charges normally but external USB-C display output dead.

Kya charging path automatically high-speed path ko prove karta hai?

SECTION L — FINAL ADVANCED PRACTICAL CASES

Case 1 — Dead Android

Phone completely dead.

Known-good battery same.

Main rail present.

PMIC VIN present.

Always-on 1.8V absent.

1.8V rail resistance very low.

Questions:

Last Good?
First Missing?
PMIC replace karoge ya pehle rail map?
Confirmation kaise loge?

Case 2 — No-Power but Low-Level USB

Phone screen black.

No vibration.

PC low-level service mode detect karta hai.

Questions:

True no-power hai?
SoC execution ke bare mein kya clue milta hai?
Next 4 stages kya check karoge?

Case 3 — Boot Loop

Phone logo par restart.

Known-good battery same.

Main rail stable.

Recovery stable.

Normal OS boot loop.

Questions:

Hardware ya software/storage direction?
First safe next step?
Kab storage hardware suspect strong hoga?

Case 4 — Main Rail “Short”

Continuity beep.

Resistance same-model known-good ke similar.

Questions:

Short confirmed?
Next diagnostic step?
Beep misleading kyun tha?

Case 5 — USB-C Fault

One orientation charges.

Other dead.

Known-good cable same.

Questions:

Main suspect block?
CC1/CC2 role?
Charger IC ko first kyun nahi replace karoge?

Case 6 — Charging Icon No Percentage

Phone heavy gaming par charging icon show karta hai but percentage falls.

Screen off par battery increases.

Questions:

Possible cause?
Kis external cheez ko first compare karoge?
Charging icon se kya prove hota hai aur kya nahi?

Case 7 — LCD No Backlight

Phone rings.

Faint image visible.

Backlight VIN, BL_EN aur PWM present.

Questions:

Image-data path ka kya clue?
Next block?
OLED phone hota to same test valid hota?

Case 8 — Touch I2C

Known-good screen same.

Touch VDD good.

Reset good.

SDA stuck low.

Display disconnect karne par SDA stays low.

Questions:

Panel suspect strong ya board?
Next kya inspect/test karoge?
Pull-up supply ka role?

Case 9 — Audio

Main speaker dead.

Known-good speaker same.

Amp power good.

Enable good.

Digital audio bus absent.

Questions:

Amp replace karoge?
Fault upstream ya output?
Next block?

Case 10 — Camera

All cameras dead.

Camera PMIC VIN good.

All outputs absent.

Enable missing.

Questions:

Camera PMIC bad confirmed?
First missing signal?
Upstream control kaise trace karoge?

Case 11 — Wi-Fi

Wi-Fi + Bluetooth greyed.

Shared rail absent.

Regulator VIN good.

EN absent.

Questions:

Regulator replace?
Fault direction?
Antenna test useful hai?

Case 12 — Weak Wi-Fi

Wi-Fi works.

Bluetooth works.

Both have very short range.

Antenna coax loose.

Questions:

Digital ya RF fault?
Root cause?
Combo IC reflow needed?

Case 13 — No Service

SIM detected.

Baseband present.

Manual operators none.

Known-good phone same carrier/location sees operators.

Questions:

RX ya TX side?
First physical checks?
PA ko first replace karoge?

Case 14 — Network Registration

SIM detected.

Operators visible.

Carrier/account verified.

Phone cannot register.

Questions:

Receive path kitni prove hui?
Next direction?
Antenna receive-only conclusion kyun incomplete hai?

Case 15 — Battery Drain

Battery drains overnight.

Phone warm in RF area.

Airplane mode solves most drain.

Signal very poor.

Questions:

Strong subsystem?
Possible common root cause?
Battery replacement first conclusion kyun wrong ho sakti hai?

Case 16 — Random Shutdown

Phone shuts down when flash LED fires.

Known-good battery solves.

Questions:

Root cause?
PMIC repair needed?
Open-circuit battery voltage kyun enough nahi thi?

Case 17 — Liquid Damage

Phone originally no-power.

One shorted main-rail capacitor repaired.

Phone boots.

Now mic dead and Wi-Fi weak.

Questions:

Repair complete hai?
Liquid damage ka important principle?
Next diagnostic approach?

Case 18 — PMIC Hot

PMIC hottest.

One output rail low resistance.

Camera disconnect karne par resistance normal.

Questions:

PMIC root cause?
Faulty block?
Heat clue ka correct interpretation?

Case 19 — UFS

Phone boot nahi karta.

Battery/power good.

UFS power/reset/clock correct.

Official flash repeatedly same stage fail.

External causes ruled out.

Questions:

Strong direction?
BGA/IC immediately remove?
Customer data important ho to kya consideration hai?

Case 20 — Foldable

Outer screen perfect.

Inner screen black.

Touch inner dead.

Problem hinge movement ke baad start hui.

Questions:

Shared SoC fault strong hai?
First local blocks?
Device ko repeatedly fold/unfold karke test karna kyun wrong?

Case 21 — Dual Battery

Phone random shutdown.

Battery Pack A detected.

Battery Pack B intermittently missing.

Questions:

First checks?
Direct-charge Pack B?
Data/temp lines important kyun?

Case 22 — Previous Repair

Phone no boot after previous board work.

Major storage IC reworked.

Microscope mein nearby tiny resistor missing.

Schematic shows it belongs to storage reset/control path.

Questions:

Storage IC reball first?
More logical repair?
Recent-repair rule explain karo.

Case 23 — Fuse

USB input fuse open.

VBUS fuse input par present.

Downstream rail resistance very low.

Questions:

Fuse simply replace?
Fuse bridge?
Correct order?

Case 24 — Regulator

VIN = good.

EN = good.

OUT = missing.

Output rail resistance same as known-good.

Questions:

Strong suspect?
Konsi evidence is suspicion ko strong banati hai?
Replacing regulator ke baad kya re-measure karoge?

Case 25 — Restart Sequence

Phone repeatedly boots/restarts.

Scope:

Rail A drops.

50 ms later Rail B drops.

100 ms later EN signal drops.

Questions:

First Falling Point?
Rail A ya controller EN first suspect?
Why?

FINAL MASTER ORAL QUESTIONS

Question 153

Aap ke paas ek completely unknown dead phone aaye.

First 10 diagnostic steps verbal sequence mein batao.

Question 154

Aapko ek unknown rail par continuity beep milti hai.

Is reading ko interpret karne ka complete process batao.

Question 155

Customer kehta hai:

“Phone ka motherboard short hai.”

Aap technician ke taur par is statement ko kaise verify karoge?

Question 156

Ek phone repair ke baad ON ho gaya.

Kya repair complete hai?

Full QC ka reason explain karo.

Question 157

“Current draw 0.xxA = UFS fault.”

Is statement mein technical problem kya hai?

Question 158

“IC garam hai = IC faulty.”

Is statement mein problem kya hai?

Question 159

“Phone drop hua = CPU reball.”

Is approach mein kya galat hai?

Question 160

Professional repair technician aur parts-changing technician mein kya difference hai?

Final Practical Worksheet

Candidate Name: __________

Date: __________

Device: __________

Complaint: __________

Actual Verified Symptom: __________

History: __________

Known-Good External Tests: __________

Affected Block: __________

Main Rail: __________

Last Good: __________

First Missing: __________

First Falling: __________

Voltage Measurements: __________

Resistance Measurements: __________

Diode Measurements: __________

Clock: __________

Reset: __________

Communication Bus: __________

Peripheral Isolation: __________

Schematic/BoardView Findings: __________

Root-Cause Hypothesis: __________

Confirmation Test: __________

Confirmed Root Cause: __________

Repair Action: __________

Post-Repair Measurements: __________

Final QC: __________

Final Scoring System

CORE MOBILE MASTER COURSE

Mobile Part 34 se Part 38:

ADVANCED EXTENSION

Is point par Mobile Repair Course mein:

Theory
Architecture
Board-level diagnostics
Practical fault workflows
Component testing
Current-draw interpretation
BGA diagnostic theory
Foldables/tablets
Shop workflow
Final exam

sab cover ho chuka hai.

Next Step

FINAL EXAM ANSWER KEY

Ab jab answers start karenge to Question 1 se sequentially answer key bana sakte hain, lekin exam ke questions se separate rakhenge taa ke pehle aap khud solve kar sako.