Add internal usb thumbdrive part 1

A few times a year, we have PC shows in my part of the world. In any other place, a PC show is where companies showcase their greatest new gadgets and computing devices. However, in my town, a PC show is always a good excuse for cheap sales.

We of the tech world are often loaded with gadgets, most which we have little use for. These gadgets were truthfully a bunch of junks we wasted money on. We bought them in a moment of passion, used them a few times, and then stuffed them into a drawer to gather cobwebs. Maybe we could pretend we were supporting the economy by our spending. Personally, I have forced myself into the habit of not buying everything in sight.

The secret to that habit is, of course, avoiding the PC shows in the first place (duh!)

Thus, I was really asking for it when I visited a PC show two months ago. I couldn’t resist getting a new USB thumbdrive. Come on, 50 bucks for 8 gig? After I returned home and before I could feel the creeping regret of spending callously, I quickly thought of a use for the drive.

Actually, I already owned a two-year-old beat up 8 gig thumbdrive. I used this drive to hold data that I carry around everywhere. Now that I have a new drive, I transferred the data from the old to the new drive. Then, I took the old drive and spliced it into the Linksys NSLU2.

Old and new thumbdrives


Step 1: Pry open the thumbdrive

This was not strictly necessary, but I loved to disassemble stuffs. First, remove the swivel cap, then cut along the seams of the thumdrive casing. Carefully pry the two halves apart.

Disassembled thumbdrive


Step 2: Protect the internal board

A close look at the internal board revealed a problem: there was a manual rework on the board, which could be susceptible to breakage. Recalled that the thumbdrive was two years old. When the drive was new, 8 gig flash memory chip was not available. The manufacturer must have worked around that by using two pieces of 4 gig chips. To cramp both chips in the tiny casing, they stacked the chips on top of each other. This was a neat trick, because both chips were connected to the same signal bus. The only problem was you need to route the chip-select signals separately, hence the ugly rework.

Rework in internal board


This was actually a good discovery. As I mentioned earlier, it was not strictly necessary to dismantle the thumbdrive. But I did it anyway, and discovered something interesting.

In my experience as an electronics engineer, we would have strictly avoided such method. In high volume manufacturing, manual labour is more expensive than machine assembly. However, here was an unique and innovative example of someone finding the justification to use the extreme measure. Not only was manual labour used, it was a difficult and error prone soldering task. I could only imagine the low manufacturing throughput caused by this rework. My guess: market competition to be the first with 8 gig thumbdrive made it necessary.

Interesting discovery aside, I needed to prevent the rework from breakage. In came the trusty old heat-glue gun. I encased the entire surface of the board with a thin layer of glue to hold everything in place.

Encased internal board


Before proceeding any further, I tested the thumbdrive to make sure it was not damaged during the process. Since the board was exposed, I have to avoid applying too much pressure while plugging/unplugging it to a PC.

In the next “Hacking Linksys NSLU2″ post, I will continue with modification to the slug to accept an internal usb thumbdrive.

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