820-3478 – Apple A1419
The Apple A1419, Apple J17 and Apple J17PVT are built on the 820-3478 board. The catalog lists 3 files for it: 1 BIOS file, 1 schematic and 1 boardview.
File names mention revision A. The BIOS dumps are 8 MB images. First posted in October 2021 in Schematics & Boardviews Archive, Cyberlan Electronics and BIOS Skema Boardview Laptop.
BIOS dumps 1
Schematics 1
Boardviews 1
Board facts
| Board number | 820-3478 |
|---|---|
| Numbering | Apple board number |
| Revisions | A |
| BIOS chip size | 8 MB |
| First seen | 2021-10-27 |
| Source channels | Schematics & Boardviews Archive, Cyberlan Electronics, BIOS Skema Boardview Laptop, BIOS Archive |
| About the number | Apple logic boards are numbered 820-xxxx or 820-xxxxx; the trailing letter is the revision. |
Apple models for this logic board
| A-number | Model | Years |
|---|---|---|
| A1419 | iMac 27-inch | 2012–2019 |
A-numbers come from the file names; the model names and years are Apple's published identifiers.
Laptops that use 820-3478
- Apple A1419
- Apple J17
- Apple J17PVT
What these files are for
A BIOS dump is a full image of the board's SPI flash chip. It is written back with an SPI programmer when the original firmware is corrupted, after a chip replacement, or to recover from a failed update. Read and save the original chip first: serial number, DMI data and the Intel ME / AMD PSP state differ between boards.
A schematic is the circuit diagram of the main board: power rails, power-up sequence, component values and net names. It is the reference for measuring voltages and tracing a fault.
A boardview is the component placement map of the PCB: click a part or a net and the viewer highlights where it is and what it connects to. Used together with the schematic to find test points.
Tools to open these files
| Format | What it is | Open with |
|---|---|---|
| .bdv | Honhan .bdv boardview | OpenBoardView, FlexBV or Honhan BoardViewer |
| .brd | .brd boardview (Test_Link format) | OpenBoardView, FlexBV or BoardViewer |
| PDF schematic | any PDF reader; Sumatra PDF and Foxit handle large schematics well | |
| .rar | RAR archive | 7-Zip or WinRAR |
| .zip | ZIP archive | 7-Zip, WinRAR or the built-in Windows extractor |
| .bin | BIOS image inside the archive (usually .bin) | a CH341A, XGecu T48 / TL866II Plus or RT809H programmer |
Questions
What BIOS chip size does 820-3478 use?
The BIOS images for 820-3478 are 8 MB.
Which laptops use the 820-3478 board?
Files in the catalog link 820-3478 to the Apple A1419, Apple J17 and Apple J17PVT.
Is there a boardview for 820-3478?
Yes, 1 boardview file in .bdv and .brd format.
Where do the download links go?
Each button opens the original public Telegram post the file was shared in. ChambersDesignInc.com only indexes and cross-references those posts.