Rosewill USB OTG Memory Card Reader (RHBM-100-U2) Teardown

I got this thing from a “Does Not Work” box intending to do a teardown. Since it’s so small, I thought it would be fun and quick, but I kept putting it off. It’s been sitting adjacent to my workbench through several reorganizations and cleanups, and I kept moving it from one place to another. Today I was about to move it again when I decided: No more. I have other things I need to do, but I’m putting them on pause for this thing. Today is the day.

Based on all the slots on one side, this is clearly a multi-format flash media reader/writer. The other end was a little more interesting, as it is a USB micro-B plug instead of the usual socket. The presence of the plug implies this was designed for use with USB OTG devices such as an Android phone, allowing them to read and write flash cards. Aside from a few labels for the various types of flash media, there was only the “Rosewill” brand logo. I found no model number or serial number printed on the enclosure. Searching for “Rosewill USB OTG” retrieved information on many products. The closest match based on pictures is the RHBM-100-U2.

There was a visible seam around the faceplate full of memory slots. The remainder of the enclosure appeared seamless. The lack of fasteners indicate this faceplate is glued in place. Using pliers, I was able to get a bite out of the enclosure to use as starting point. Not elegant, but I’m going for speed in this teardown and elegance be damned.

The bite allowed my pliers to get a firm grip on the faceplate and peel all around the perimeter. After that, I could pull the faceplate free.

Once the faceplate was removed, a firm push on the USB micro-B plug popped the final few glue points free and I could slide out the PCB. As expected, it was relatively simple dominated by surface mount flash media connectors.

Aside from those media connectors, one side was dominated by small passives.

The other side had one IC clearly more sophisticated than anything else on the device. The only other unexpected item is the black goo on the USB micro-B plug. I have no idea why that is there.

Searching on “GLB23” didn’t get me anywhere, but “GL823” got a likely hit with Genesys Logic. It is advertised as a single-chip solution for implement a multi-format USB media card reader, which is a perfect match for the device at hand. I didn’t bother downloading its datasheet, but I wouldn’t be surprised if this device basically followed the reference design.

Years after I picked this up, intending for a quick teardown, I finally did it. It no longer needs to occupy space on my workbench and I can move on with my life.

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