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Crestron MC3 Tear-down

Saw another wave of failed MC3 processors while browsing the Crestron forums so I decided I’d better make a backup of my SD card while I still could.

To get the cover off, I had to remove all visible screws from the outside (including the grounding screw). There’s also a lock nut on the RF antenna that had to be removed. The whole board slides out from the rear of the unit.

Once out of the chassis, there are two plastic screws holding a daughter board down. I removed those, then pulled the daughter board out. This exposes the SD card below. I had to slide the SD card to the right to unlock the socket, then I could remove it.

Daughter board removed to expose SD card slot

Using Ubuntu, I made a copy of the SD card and compressed it for storage in my Dropbox:

$ dd if=/dev/sde of=mc3-sd-card.img
$ bzip2 -v9 mc3-sd-card.img

Now I have a copy of the SD card saved, I wondered what was actually on it. First I tried fdisk to see what it reported:

$ fdisk -l mc3-sd-card.img
Disk mc3-sd-card.img: 1.9 GiB, 2027945984 bytes, 3960832 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

So fdisk didn’t detect any partition scheme. Maybe it’s just a FAT file system?

$ sudo mount -t vfat -o loop,ro mc3-sd-card.img /mnt
mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop6, missing codepage or helper program, or other error
$ sudo mount -t auto -o loop,ro mc3-sd-card.img /mnt
mount: /mnt: wrong fs type, bad option, bad superblock on /dev/loop6, missing codepage or helper program, or other error

What’s in this file? Using hexdump, I can page down and find messages about the Windows CE Ethernet Boot loader…

000219a0  31 39 3a 34 31 3a 33 33  00 00 00 00 4f 63 74 20  |19:41:33....Oct |
000219b0  20 37 20 32 30 31 35 00  57 69 6e 64 6f 77 73 20  | 7 2015.Windows |
000219c0  43 45 20 45 74 68 65 72  6e 65 74 20 42 6f 6f 74  |CE Ethernet Boot|
000219d0  6c 6f 61 64 65 72 20 25  64 2e 25 64 20 28 25 73  |loader %d.%d (%s|
000219e0  20 25 73 29 20 66 6f 72  20 43 72 65 73 74 72 6f  | %s) for Crestro|
000219f0  6e 0d 0a 00 50 52 4f 47  52 41 4d 20 52 45 51 20  |n...PROGRAM REQ |

I’m sure there is some information to be found reading Microsoft’s documentation. Maybe I’ll come back to this again someday?

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