Tearing Down the Boss Phone

Poke around enough on AliExpress, Alibaba, and especially Taobao—the Chinese facing site that’s increasingly being used by Westerners to find hard to source parts—and you’ll come across some interesting things. The Long-CZ J8 is one of those, it’s 2.67 inch long and weighs just 0.63 ounces, and it’s built in the form factor of a Bluetooth headset.

A couple of months ago Cory Doctorow highlighted this tiny phone, he’d picked up on it because of the marketing. The lozenge-shaped phone was being explicitly marketed that it could “beat the boss”. The boss in question here being the B.O.S.S chair—a scanning technology that has been widely deployed across prisons in the U.K. in an attempt to put a halt to smuggling of mobile phones to inmates.

The Long-CZ J8 is just 2.67 inch (6.8cm) long.

I wasn’t particularly interested in whether it could make it through a body scanner, or the built-in voice changer which was another clue as to the target market for the phone. However just the size of the thing was intriguing enough that I thought I’d pick one up and take a look inside. So I ordered one from Amazon.

It’s hard to get across how small this phone is, at 68mm×23mm×11mm it’s about the size of my thumb, and it weighs just 18g.

It is pretty easy to lever the casing of the phone apart with a metal spudger, because there are no screws. Although if you want to have a go yourself, you should be careful to start on the side away from the SIM card slot as it turns out the two halves of the phone are connected by some flying wires.

Opening the phone up reveals a 260 mAh battery—which provides up to 5 hours of talk time, or 3 days on standby—charging is via the micro-USB port at the top of the phone. The battery is connected to the main board with two wires. On the same side of the phone is a speaker, used when the phone is hooked around the ear like a Bluetooth headset.

The Bluetooth antenna is nothing more than a small length of wire that can be seen to the right of the RF shield, just down from the speaker.

Teasing these out of the back shell is again a job for a metal spudger and doesn’t present a problem. Popping the main board out of the other half of the case also involves prying the microphone out of the case before you can put any force on the board.

The disassembled Long-CZ J8.

The front shell contains the rubberized keycaps as a separate insert, and another small speaker located above the screen that can be pried out with a craft knife—it’s glued into the shell, but the glue isn’t particularly sturdy.

The main board is mostly covered by an RF shield, with the micro-SIM card slot just below it. Flipping it over we can see the small TFT screen, the keyboard, and some LEDs that light the keycaps up when the phone is in use. If you want to you can pry the white keyboard overlay up with a fingernail to reveal the circuit board underneath.

The screen itself is glued (tacked might be more accurate) down to the main board and can be gently pried up with a fingernail to reveal the connector ribbon cable which is soldered to the board. There are pretty much no connectors on the board, everything is soldered — or glued—directly to the PCB.

The front of the main board of the Long-CZ J8.

Flipping the board back over, and prying the RF shield off the back of the board with our handy metal spudger, reveals the only two pieces of silicon on the board.

The main chip is a Spreadtrum SC6531, it’s a single chip based baseband transceiver aimed squarely at the low-end feature phone market. Based around an ARM926EJ-S processor — an entry point ARM, although one still capable of running a full operating system like Linux or Symbian. It’s actually overpowered for this phone, the chip provides support for a 2MP camera. You can pick up the SC6531 on AliExpress for around $3.00 a piece in small lots.

The only two pieces of silicon on the Long-CZ J8 main board.

The other silicon present on the phone is the HunterSun HS8292U. It’s an RF chip for quad-band 2G GSM/GPRS cellular handsets at 850, 900, 1800, and 1900MHz. You can pick it up on AliExpress for under $2 a piece.

It was really interesting to compare this phone with the $12 “Gongkai” phone that Bunnie Huang picked up a few years ago at the Mingtong Digital Mall in Shenzhen. The build quality and design were pretty similar, this was just a lot smaller, showing perhaps how the technology stack has matured over the last couple of years.

The Long-CZ J8 itself can be picked up on AliExpress for around $20—about half the price its selling for on Amazon—and I’m fairly sure it’s available for much less in Shenzhen, possibly around the same price as Bunnie’s “Gongkai” phone. So if you’ve seen it around in Shenzhen, I’d be interested in hearing what it’s selling for in the markets.

This entry was posted in Boss Chair, Boss Phone, Bunnie Huang, cellphone, Cellphone Hacks, cory doctorow, Featured, Gongkai, Long-CZ J8, teardown. Bookmark the permalink.

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