1.14.2008

A Naked Chumby

The Chumby is marketed as a 'hackable device'- but I guess this only applies to the software as it appears to have been purposely made not easy to open.

To disassemble a Chumby, you need to pull the vinyl off the surrounds the screen.  It is glued (with some sort of plastic or rubber cement) so it probably will not be an entirely 'clean' opening (click on any image for a link to my Flickr pages for a much larger version for more details).

 Chumby_055

After the screen section is removed, disconnect the 26 wire ribbon cable from the back of the screen (it is keyed, so it will only go back together one way).  Remove the cotton stuffing from the top and the bean-bag material from the bottom of the case to allow access to the speaker/rear panel assembly.

The ribbon cable suggests that one can mount the screen somewhere away from the main body (say in a nightstand?).  The fault with this is idea is that the 'bend switch' is located in the other part of the device- so it must be accessible to get to menu features.

Chumby_054

The speaker assembly is held in by four tiny (#00, I believe) Phillips screws.  Two of these are visible at the bottom edge of the speaker assembly; the other two are about 1 1/4" above the others but they are hidden behind the wiring plugs for the speakers and power.  (Note: The speaker and power plugs are identical- so if you remove these please be very sure you put them back in the same place!).  The speakers assembly will come out easily after the screws are removed.

The speaker connection, power plug and 9v power cable are all detachable, so they can easily be extended to another location if desired (i.e. 12V input for a car mount)

Chumby_053

The rear panel is held on by double-stick tape (and the four screws that were removed in the above step).

Here are some pictures of the full Chumby assembly minus the case:

There is a sub-board that is sandwiched above the main PCB via two long Philips screws and some plastic stand-offs.

The sub-board is the 'WiFi Riser board'.  It is connected via a short USB cable and is home to a Xterasys 3135G 802.11g USB Wifi adapter (minus the blue plastic case).  There is a bright blue LED on the WiFi adaptor that indicates it is powered on.  The thermal putty on the adapter seems to serve two purposes; heat dissipation and to maintain space between the WiFi adaptor and the main board.

I am not sure why they opted for an entire sub-board instead of using a short USB extender as this appears to be the sole function of the sub-board.  The connecting cable is USB-A plug to USB-A plug and the board is USB-A receptacle to USB-A receptacle; a short USB extension cable would have accomplished this...

Chumby_058

Chumby_059

The main board sits behind the LCD.  It has two ribbon cables on the bottom; one (larger) one for the LCD display and another (smaller) one for the touch-screen.   On this side of the board sits the 64MB Flash RAM chip (Hynix HY27US08121M) and two USB Transceiver chips (Sipex SP5301C).

Note the 'with love -bunnie' inking on the top left of the board.  :o)

Chumby_060

Releasing the ribbon cables allows access to the underside of the main board.  The board can now flip up- held in place by the copper tape on the other side of the board. On this side we find the CPU (Freescale Semiconductor MC94MX21DVKN3), two 32MB RAM chips (Hynix HY57V561620CTP-H). the touchscreen controller/DAC (Ti TSC2100) and another USB Transceiver chip (Sipex SP5301C). 

There is some more thermal putty on this board- covering most of the CPU and part of the memory modules- that also acts as a spacer/insulator between the mainboard and the back of the LCD screen.  Removing the thermal putty also removed most of the identification markings on the memory and CPU chips.

Chumby_062

Re-assembly notes:

The 'bend switch' is a microswitch with a piece of metal extended up to the top of the Chumby.  It takes a bit of experimenting to get the cotton re-packed in the unit so the switch is not accidentally activated by the vinyl case (i.e. don't re-glue the screen to the case until you have verified the switch is not 'stuck').

3 comments:

  1. Hey i have a question for you, you seem to know a bunch about the chumby, and i am running into an issue with it at work.



    there is currently no way to accept a EULA page from a hotspot or corporate wifi connection and i was wondering if there was some way around this to get the chumby up and running for me at work.


    i just bought a new power adapter so i could bring it to and from work in my briefcase, without wires. but then i ran into this issue of a EULA which i obviously dont run into at home.


    any advice would be amazing!

    ReplyDelete
  2. @withgraceilead These pages might help with your EULA problem:

    http://wiki.chumby.com/mediawiki/index.php/Chumby_tricks#Use_wifi_protected_by_a_capture_page

    http://forum.chumby.com/viewtopic.php?pid=6135#p6135

    The forums and wiki are better resources for this sort of thing.

    ReplyDelete
  3. Anonymous7:48 PM

    Hello, could you specify the type of Chumby's touch screen? Press type, field type or IR detecting type?

    ReplyDelete