TELEPHONY
A B
CD
Fig. A: Chumby dissected: the original leather case,
the core unit, the rear unit with Chumbilical attached,
and the cotton stuffing. Fig. B: The core unit with the
USB riser card in place. Fig. C: The riser circuit board
(lifted here) is a primarily blank board used to lift the
third component, the USB wi-fi module, off the main circuitry. Fig. D: The interior of the phone prior to gutting
all the components.
MATERIALS
Chumby
Desk phone
Workable material to make a small bracket Any
kind of wood, metal, or plastic that you can
size and shape will do. I used a spare, bendable
metal belt from a VEX Robotics kit.
Mounting tape
26-pin 0.1"-spaced dual-row female connectors
( 2) from an electronics parts store
26-wire, 0.1"-spaced ribbon cable, 6" long You can
use wider cable; I bought 32-wire cable and
peeled away the excess.
Small panel-mount momentary
push-button switch
Insulated hookup wire
TOOLS
Hobby knife
Thin screwdriver
Jigsaw or Dremel with cutting bits I used a Dremel,
but jigsaw cuts would have been straighter.
Cardboard
Pencil or thin marker
Multimeter
158 Make: Volume
16
plastic bezel and the leather case on the outside to
release the glue. Peel back the case from the bezel,
and the main assembly, known as the “core unit,”
pops out. This core unit is attached to a 26-pin
ribbon cable (the “Chumbilical”), so be gentle when
removing it.
Disconnect the Chumbilical from the core unit and
remove all the stuffing inside, so you can access the
rest of the components more easily (Figure A). The
other end of this ribbon cable attaches to a small
“daughtercard,” which carries the charger port, USB
ports, headphone jack, on/off button connector,
and a hidden 9-volt battery connector. Unscrew the
4 small screws that attach this daughtercard to the
plastic at the rear of the Chumby, and remove the
entire rear assembly.
The core unit (Figure B) consists of 3 circuit
boards. The main circuit board affixed to the LCD
contains all the major electronics, including the
CPU, memory, display controller, and a USB port
that connects to the second board: the USB riser.
The riser is a primarily blank board used to lift the
third component, the USB wi-fi module, off the
main circuitry. The USB riser’s empty back makes
it a good surface for mounting additional hardware
(Figure C).
