BYTE SHERLOCK REPAIR BIBLE
Every tool setting · Every repair · Every diagnosis - Mobile + Laptop
Tool settings for your exact bench 30+ mobile jobs · 30+ laptop jobs Diagnostic decision trees
Sayan Roy Chowdhury - Byte Sherlock, Barrakpore 700122 - v1, 05 Oct 2026 - companion to the 91-Day Plan & Bench Handbook
HOW TO USE: Section 1 = what to set on every tool before every job (keep open at the bench). Section 2-3 = every repair you will ever see in Barrakpore: symptoms → diagnosis → fix. Section 4 = the thinking method - decision trees that make you a diagnostician, not a parts-swapper. Section 5 = quick reference tables to print and hang on the wall.
SECTION 1 - TOOL SETTINGS BIBLE
1.1 Soldering iron - OSS T210 (C210 cartridges)
| Task | Temperature | Notes |
|---|
| Through-hole joints, connectors, shields | 330-350°C | Bigger metal = more heat needed |
| SMD 0603 / 0805 resistors, caps | 300-320°C | Start of all SMD practice |
| SMD 0402 and smaller | 290-310°C | Fine tip, quick touches |
| Charging port / USB connector pins | 330-350°C | Flux helps; drag method for pins |
| SOIC-8 and small IC legs | 340-350°C | Drag solder with flux |
| Micro jumper wire (0.01-0.1mm) | 300-320°C | Fast touches only |
| Drag soldering / reflowing a row of pins | 350-360°C | Plenty of flux, steady speed |
| Lead-free solder (RoHS boards) | +10-20°C on all above | Lead-free melts hotter |
Iron rules: start at 300°C until confident · tin the tip before and after every session · wipe on brass sponge only · if a joint takes more than 3 seconds, stop, add flux, reconsider · more heat is NOT the fix for a bad joint - flux is.
1.2 Hot air - Quick 857DW+
| Task | Temp | Airflow | Notes |
|---|
| Drying a washed board | 80-100°C | High | After water-damage cleaning; keep distance 8-10cm |
| SMD 0603/0805 removal | 320-350°C | Low-med | Circle motion, tweezers lift at 5-8s |
| Shield / can removal | 350-380°C | Med | Heat edges, slide blade under once solder flows |
| Small IC removal (SOIC, QFN small) | 350-370°C | Med | Preheat board area first, flux around IC |
| Large IC / PMIC / CPU removal | 380-400°C | Med-high | Preheat from below (hotplate later), protect connectors with Kapton |
| BGA reballing (with stencil) | 380°C | Low | Slow circle till balls melt, do not blow balls away |
| Connector / FPC re-solder | 330-350°C | Low | Kapton tape around parts first |
| Shrinking heat-shrink / drying adhesive | 200-300°C | Med | General purpose |
Hot air safety: ALWAYS remove the battery before hot air near it · Kapton tape over nearby connectors and plastics · keep the nozzle moving - a parked nozzle kills components · point away from your face; fumes rise · after removing a shield, the board underneath is 350°C - wait before touching.
1.3 DC power supply - Sugon 3005PM (with short killer)
| Job | Voltage | Current limit | What you learn |
|---|
| Phone battery direct supply (dead phone test) | 3.7-4.0V | 0.5-1A | Standby draw 0.01-0.03A = healthy; read the behavior |
| Phone boot-draw test | 4.0V | 2A | Press power, watch the current steps |
| Phone SHORT finding | 1.0-2.0V | 2A | Short killer pulse → then freeze spray / IPA on components |
| Battery boost / activate (deep-discharged battery) | 3.7-3.8V | 0.2-0.5A | Wake the battery until it accepts normal charge; STOP if it heats |
| Laptop supply (test boot) | 19V (19.5V Dell/HP some, 20V Lenovo) | 2-3A | Check the original adapter label first! |
| Laptop rail voltage injection (shorted rail) | rail voltage +0.2-0.5V | 0.5-1A | The shorted component warms; find with freeze spray |
| Laptop rail diagnosis (read-only) | 0V (board off) | - | Diode mode / voltage measuring only |
| Charging a battery through phone (charge test) | 4.2V | 0.5-1A | Watch the phone's own charging behavior |
PSU golden rules: set CURRENT LIMIT before connecting - the limit is the safety net · output OFF before connecting AND before disconnecting · red = positive, black = negative; reversed polarity kills boards instantly · if the supply shows a steady short (max current at tiny voltage), stop and diagnose, do not push.
1.4 Multimeter - all readings reference
| Measuring | Mode / Range | Healthy reading | Fault reading |
|---|
| Phone battery voltage | DC V, 20V | 3.7-4.2V (full=4.2, storage=3.8, low=3.4, dead=<3.0) | 0V = dead cell / protection tripped |
| Charger output (USB-A) | DC V, 20V | 4.75-5.25V | 0V or <4.5V = bad charger |
| Fast-charge negotiation | DC V, 20V | 5V idle; jumps to 9V/12V when phone requests | Stuck at 5V with fast phone = cable/protocol issue |
| Laptop adapter output | DC V, 200V | 19-20.5V | 0V / fluctuating = adapter dead |
| Phone charging port VBUS (charger in) | DC V, 20V | ~5V at port pin | 5V at cable but 0V at board pin = broken fuse/line |
| Speaker / ringer | Resistance Ω, 200 | 8Ω, 16Ω or 32Ω (typical) | OL = dead coil |
| Vibration motor | Resistance Ω, 200 | 10-30Ω | OL = dead |
| Microphone | DC V (bias test) | ~1.8-2.8V bias on mic pin | 0V = mic line/power fault |
| Fuse | Continuity | Beeps (near 0Ω) | No beep = blown fuse |
| Coil / inductor | Resistance Ω | Near 0Ω is NORMAL (coils are near-shorts by design!) | OL = open coil |
| Capacitor (small) | Diode mode | Brief charge, then OL | Beeps steady both ways = shorted cap |
| Rail to GROUND (board off) | Diode mode | 300-800 typical | <100 or beeps = shorted rail |
| Diode (any) | Diode mode | 0.4-0.7V one way, OL other way | 0.00 both ways = shorted; OL both ways = open |
| Mobile battery connector (both ways) | Diode mode | ~0.4-0.6 one way, higher/OL other | Beeps both ways = short on power rail |
| Resistor | Resistance Ω | Reads its marked value ±5% | OL = cracked/open |
Multimeter rules: NEVER resistance/continuity on a powered circuit · never current mode across a voltage source · when value unknown, start at the highest range · touch probes together in continuity mode first to confirm the meter works.
1.5 Microscope - RF4 RF7050 TVP+
| Setting | Value | When |
|---|
| Zoom | 7-50X (use 10-20X for soldering, 30-50X for inspection) | Soldering at lower zoom = easier depth perception |
| LED ring | 30-60% brightness | Full brightness washes out solder shine; find solder joints' gleam at moderate light |
| Focus | Adjust with board flat on mat, not held | Coarse then fine; re-focus after zoom changes |
| Working distance (0.5X CTV) | ~10-15cm between objective and board | Room for iron under the lens |
| Camera (DKP when it arrives) | USB to laptop; OBS for recording | See the streaming setup in the Bench Handbook |
1.6 CH341A programmer - BIOS reading (WARNING inside)
| Setting | Value | Note |
|---|
| Clip orientation | Red dot/wire = pin 1 of the SOIC-8 chip | Pin 1 = marked dot on chip; wrong way = no detection or damage |
| Software | AsProgrammer / NeoProgrammer (free) | Select correct chip from the list (read the marking, e.g., W25Q64, MX25L64) |
| Voltage | CHECK CHIP VCC FIRST! | CRITICAL: many CH341A clones feed 4-5V on VCC - if the BIOS chip is a 1.8V chip (common on 2019+ laptops and phones), a raw clip connect can KILL it. Use the 1.8V adapter board or a modified 3.3V CH341A. |
| Workflow | Read → save → read → save → compare → edit → write → verify | Two identical backups before ANY modification |
1.7 Other tools - quick settings
| Tool | Setting | Notes |
|---|
| iBoot AD Max+ cable | Into battery connector; PSU feeds through it | For phones with non-removable batteries; also boots iPhone into DFU |
| XTC separator | Plate 80-100°C LCD / 60-80°C OLED | Soften glue 1-2 min, molybdenum wire slice; never force cold glass |
| USB-C PD tester | In line between charger and phone | Reads V, A, protocol (5V/9V/12V). Use to prove "charger fine, phone not pulling" vs "charger dead" |
| Ultrasonic (when bought) | 40kHz, 5-10 min cycles | Distilled water + IPA mix or PCB cleaner; dry board fully after; never with battery connected |
| Freeze spray | 10-15cm distance, 2-3s bursts | After short-killer pulse; the shorted chip stays warm / behaves differently |