Original BIOS dump
The first uploaded original is locked to this diagnostic session and cannot be overwritten by this workflow.
TCS Pune
820-02862 – Bench Power & Signal Checklist
Board-specific bench checklist derived from 1 supplied source PDF(s). Source coverage: Limited. Verify exact thresholds, pin numbers and rail tolerances against the source schematic and component datasheets before component replacement or voltage injection.
Compatible models: Apple KBD -02 ( )
⚠ Safety: Disconnect battery before resistance/diode checks. Use current limiting for injection. Never inject voltage into an unknown rail until its safe voltage/current limit and isolation path are confirmed. Use a short ground spring for high-speed oscilloscope probing.
🛠 Required Tools
- Digital multimeter Oscilloscope with x10 probe Bench power supply with current limit Thermal camera / freeze spray as required SPI programmer where firmware diagnosis is required
0 / 5 done
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Schematic-derived bench record
Bench Manual & Source Coverage
Source coverage: Limited. Values and thresholds must still be verified against the exact schematic/datasheet.
Source PDF(s): Apple KBD 820-02862-02 (Silkscreen).pdf | MacBook Air 13#U00e2_#U00b3 M2 A2681 - 820-02862 Schematic.pdf
Table A
Chronological Power Sequence
Follow upstream to downstream. A missing later signal may simply be the result of an earlier missing prerequisite.
| # | Stage | Signal / Rail | From -> To | Ref | State | Expected | DMM | Oscilloscope |
|---|---|---|---|---|---|---|---|---|
| 1 | Main Rails | +3.3V system rail | System 3.3 V rail | 820-02862 schematic p.1 | Follow chronological sequence | Nominal 3.3 V-class system rail. | Measure at regulator/output test point. | Stable DC. |
| 2 | DC Input | Adapter / DC-IN main rail | Input connector / protection path | 820-02862 schematic p.23 | Follow chronological sequence | Board-specific adapter/input voltage; verify adapter or USB-C contract and schematic. | Measure DC to ground at the input/protection path. | Flat DC; investigate collapse or excessive ripple. |
| 3 | Charger | ACOK / ACIN | Charger -> EC/SMC | 820-02862 schematic p.1 | Follow chronological sequence | Valid adapter-present logic state; polarity is board/IC specific. | Measure logic level and insertion/removal transition. | Clean state transition. |
| 4 | EC / SMC | EC / KBC / SMC supply | EC/KBC/SMC power | 820-02862 schematic p.1 | Follow chronological sequence | Controller supply must be valid before sequence outputs are expected. | Measure controller supply rail(s). | Flat DC; no repeated collapse. |
| 5 | EC / SMC | 32.768 kHz RTC / EC clock | RTC / EC low-frequency clock | 820-02862 schematic p.40 | Follow chronological sequence | Stable low-frequency oscillation where applicable. | Use high-impedance scope probe; avoid loading crystal nodes. | ~32.768 kHz waveform where exposed. |
| 6 | BIOS / SPI | SPI chip select | Controller -> SPI flash | 820-02862 schematic p.23 | Follow chronological sequence | Idle/inactive with access pulses during firmware fetch. | Scope during power-on/reset release. | Chip-select pulse bursts. |
| 7 | BIOS / SPI | SPI clock | Controller -> SPI flash | 820-02862 schematic p.23 | Follow chronological sequence | Clock bursts during flash access. | Scope during firmware access. | High-frequency clock bursts. |
| 8 | Display | eDP HPD | Panel -> GPU/PCH/SoC | 820-02862 schematic p.6 | Follow chronological sequence | Valid board-specific HPD state when panel is detected. | Measure with panel connected and powered. | Clean logic level/transition. |
| 9 | Display | Backlight enable | EC/PCH/GPU -> backlight | 820-02862 schematic p.77 | Follow chronological sequence | Board-specific active state after panel initialization. | Measure enable logic when backlight should be active. | Clean assertion. |
| 10 | Display | Backlight PWM | EC/PCH/GPU -> backlight | 820-02862 schematic p.9 | Follow chronological sequence | PWM activity when brightness is nonzero; exact duty/frequency is platform specific. | Scope PWM and record duty/frequency. | Stable PWM waveform. |
| 11 | Battery / Bus | SMBus / I2C activity | EC/charger/battery bus | 820-02862 schematic p.24 | Follow chronological sequence | Pulled-high idle with transaction bursts when devices are queried. | Scope clock/data and confirm pull-up rail. | I2C/SMBus clock/data bursts. |
| 12 | USB-C / PD | USB-C CC1 / CC2 | USB-C port -> PD controller | 820-02862 schematic p.1 | Follow chronological sequence | Valid attachment/orientation state; exact voltage depends on Rp/Rd and role. | Measure CC states according to controller datasheet and port orientation. | Observe attach/orientation changes. |
| 13 | USB-C / PD | PD negotiation / contract | USB-C PD controller | 820-02862 schematic p.1 | Follow chronological sequence | Contract may be 5/9/15/20 V or PPS depending platform/source. | Verify default VBUS first, then observe negotiation and final contract. | PD communication / VBUS transition when negotiation succeeds. |
Table B
Bench Reading & Fault Isolation
Enter the actual DMM reading and scope/logic observation. Select PASS, FAIL or N/A, then tick Checked when that row is complete.
0 / 13 checked
| Checked | # | Signal / Rail | Measured | Observed Waveform / Logic | Result | Failure Isolation Hint | Technician Notes |
|---|---|---|---|---|---|---|---|
| 1 | +3.3V system rail820-02862 schematic p.1 | Missing: inspect source enable, regulator input and load.Additional readings | Technician evidence | ||||
| 2 | Adapter / DC-IN main rail820-02862 schematic p.23 | No input: inspect source, connector, fuse/protection path and system-rail short.Additional readings | Technician evidence | ||||
| 3 | ACOK / ACIN820-02862 schematic p.1 | Missing: verify charger VCC, ACDET, source qualification and pull-up rail.Additional readings | Technician evidence | ||||
| 4 | EC / KBC / SMC supply820-02862 schematic p.1 | Missing/unstable controller supply blocks power-button and sequencing logic.Additional readings | Technician evidence | ||||
| 5 | 32.768 kHz RTC / EC clock820-02862 schematic p.40 | Absent clock: verify oscillator supply, crystal network and controller state.Additional readings | Technician evidence | ||||
| 6 | SPI chip select820-02862 schematic p.23 | No activity: verify sequence reached firmware fetch before suspecting the flash.Additional readings | Technician evidence | ||||
| 7 | SPI clock820-02862 schematic p.23 | CS without clock suggests bus/controller path; no bus activity may be upstream sequence.Additional readings | Technician evidence | ||||
| 8 | eDP HPD820-02862 schematic p.6 | Missing: inspect panel power, cable/connector and HPD path.Additional readings | Technician evidence | ||||
| 9 | Backlight enable820-02862 schematic p.77 | Missing: inspect lid/Hall state, display initialization, firmware and control path.Additional readings | Technician evidence | ||||
| 10 | Backlight PWM820-02862 schematic p.9 | Missing PWM with enable present: inspect brightness-control source and firmware/EC path.Additional readings | Technician evidence | ||||
| 11 | SMBus / I2C activity820-02862 schematic p.24 | Stuck/no activity: inspect pull-ups, shorts and powered bus participants.Additional readings | Technician evidence | ||||
| 12 | USB-C CC1 / CC2820-02862 schematic p.1 | Abnormal state: inspect connector, ESD/protection, pull networks and controller supply.Additional readings | Technician evidence | ||||
| 13 | PD negotiation / contract820-02862 schematic p.1 | No contract: verify CC state, controller supply, dead-battery path, firmware and cable/source compatibility.Additional readings | Technician evidence |
V4.3 Bench PSU Current Profile
Board Current Sequence
Record current draw in amperes at each observable stage. Historical comparison uses successful repairs of this exact board checklist. A different reading is a clue, not a component diagnosis.
Current sequence: No readings yet
No successful-repair baseline yet
No successful-repair baseline yet
No successful-repair baseline yet
No successful-repair baseline yet
No successful-repair baseline yet
No successful-repair baseline yet
Tip: enter only stages you actually observed. For boards that never reach a later stage, leave that stage blank rather than entering a guessed value.
V4.4 Board Knowledge
Previous Solved Cases
Historical cases are diagnostic references only. Confirm readings on the board in front of you before replacing parts.
Live match: Mark a bench signal FAIL to check previous solved cases for 820-02862.
No structured solved-repair knowledge has been collected for this board yet. New V4.4 solved cases will build it automatically.
V4.5 · SIMILAR BOARD / PLATFORM MATCHING
Reference Boards
Reference only: The boards below share one or more stored platform attributes with this motherboard. Their voltages, component locations, designators, sequence details and repair findings are not automatically treated as facts for the current board. Verify against the current board schematic, boardview and measurements before use.
No sufficiently identified reference boards yet.
Matching becomes available when published board records contain exact charger IC, EC/SIO, CPU model, CPU VR controller or Platform/ODM metadata.
V4.9 Diagnostic Timeline
Repair Timeline
Bench actions are recorded in sequence for training, QC and future troubleshooting. Signal result changes remain in history even after a failed stage later passes.
The final solved forum case receives the complete timeline for this bench session. Manual actions should describe what was actually done, not a suspected cause.
GUIDED BIOS DIAGNOSTICS · V5.1
BIOS / SPI Flash Diagnostic Record
Record only measurements observed on this board. The workflow does not assume a flash voltage, logic level or firmware fault from a single reading.
Repaired BIOS dump
Stored as a separate attachment. Uploading it never modifies the original dump.
V6.4 · Repair Case Compare
820-02862 — Compare Solved Cases
Select two or more solved cases from this board. Comparison is for diagnostic reference only; different revisions can behave differently.
At least two solved cases are needed before a comparison can be created for this board.
Final diagnostic decision
Is the problem solved?
Complete the applicable checklist and bench rows first. If solved, the completed diagnostic flow is converted into a resolved Repair Forum post automatically.
Repair QC & Final VerificationRequired before solved publication
Every item must be PASS, or N/A with a reason. Any FAIL reopens the repair and blocks the solved forum post.
V5.0 Repair Case Intelligence
Board Repair Dashboard
Aggregate repair patterns for 820-02862. Historical patterns are references, not proof of the current fault.
0Recorded repairs
0.0%Solved
Not enough timeline dataAverage diagnosis time
0Rework cases
Common symptoms
No structured data yet.
Frequently failed rails / signals
No structured data yet.
Frequently replaced / repaired ICs
No structured data yet.
Common root causes
No structured data yet.
Diagnosis time is calculated from V4.9 timeline evidence when available. Only server-recorded board-linked repair cases are counted; unsaved local bench sessions are excluded. Technician performance is never exposed on this board dashboard.
USB-C / PD DIAGNOSTICS · V5.2
USB-C Power Delivery Diagnostic Record
Record observed behavior on this board and adapter. Contract voltage and controller behavior vary by platform; this module does not assume that a higher-voltage PD contract must always be present.
USB-C port fault checklist
Check only what was actually inspected. A failed item is a diagnostic clue, not an automatic component diagnosis.
820-02862 Diagnostic Patterns
Patterns are derived only from structured solved-case evidence for this board. Select a known failed signal below, or mark a bench row FAIL to open its matching history automatically.
No structured solved cases exist for this board yet. V6.9 will build patterns automatically as solved repairs are recorded.
DISPLAY / NO-DISPLAY DIAGNOSTICS · V5.3
Internal & External Display Diagnostic Record
Record board-specific observations. Missing display signals are clues only; expected voltage, polarity and timing must be verified from the schematic, panel specification or known-good board.
Internal vs external display decision tree
Complete the checks in order. The guidance below narrows the next area to inspect but does not declare a component faulty.
Record the internal and external display results to show decision guidance.
Estimated repair cost at TCS Pune
₹4,000 – ₹15,000
Final price confirmed after free device inspection. Includes 6-month warranty.
Next Measurement Assistant
Enter the actual reading and select PASS or FAIL in the bench table. The assistant follows the 820-02862 power sequence and V6.9 solved-case patterns to suggest what to measure next.
WAITING FOR READINGComplete a bench measurement
As you record actual readings, the next recommended test will appear here.
Next measurement—
Expected—
Power state—
Component / path—
Diagnostic aid: recommendations are based on checklist order and recorded repair history. Verify the exact board revision, measurement method and power state. A suggested test is not a declaration that a component is faulty.
BIOS / EC / ME Knowledge
Board-specific firmware reference for 820-02862. Verify board revision, flash voltage/capacity, EC/ME requirements and checksum before programming.
Known-good files
No V7.3 known-good file is stored for this exact board/revision.
Dump history
No V5.1 BIOS diagnostic dumps recorded for this board yet.
Verified repair references
No BIOS/EC/ME solved-case reference has been identified for this exact board yet.
Safety: Compatibility is evidence, not permission to flash. Preserve the original dump and verify voltage, capacity, EC/ME region requirements, board revision and SHA-256.