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Fixing a broken USB Graphics Tablet

4 July 2007 No Comment

I picked up my Jam Studio graphics tablet a good few years back for the price of $10. Make no mistake about it, these are a low-priced budget tablet, and they perform about that too. Anyway, a while ago our pet rats got a hold of the cord, and chewed it in two pieces. I threw away the end, but I tossed the tablet into a box and kept it for a few years and I finally dug it out yesterday.

I tore it apart, and soon realized that there was way too many wires, and none of them were standard color codes. This is because it has a weird dongle that you can attach a DB-9 serial plug onto instead of a USB. Next I noticed the Cypress Semiconductor USB controller sitting on the board. I managed to track down the data sheet to it, and enumerate which pins were which. Tracing these back to the cable I get:

Pin USB Wire Original Wire Function
E13 Black Black Ground
E16 Green Orange Data +
E18 White Green Data –
E21 Red Lt Grey +5VDC

If you want, you can tie E17 to the shield – or E17 to USB black, and E13 to the shield of the USB cable (the original cable is unshielded however).

Installing the Drivers on Windows XP

This part sucks – it’s not very intuitive at all. I’ve found it easiest to install the driver prior to plugging in the tablet, otherwise you have to do some juggling to get it to ever function. Instructions:

  • Download jamstudio-tablet-win95-98-me-2000-xp.zip and extract it to a folder someplace. This mightn’t be necessary, but I did it anyway so I could burn the driver to a CD just in case.
  • Run setup.exe from inside the driver folder, and follow the instructions. This will install the driver (but not attach it to the hardware in Windows XP) and the control panel applet.
  • Plug your tablet in. Windows XP will detect the tablet, but it won’t function yet.
  • Under Device Manager (Right-click on My Computer, choose properties, Hardware tab, then choose Device Manager), look for the two devices that represent the tablet. They should be something like USB Human Interface Device and HID-compliant device. Open up HID-compliant device.
  • Under the Driver tab, choose Update Driver. Tell it you want to select the driver yourself, and eventually you’ll convince Windows you really do want to select the driver yourself. By this time, it should pop up the list of similar devices, one of which should be KBGear Jam Studio Digitizer. Select it, then dismiss all dialogs.
  • On both my computers, the digitizer now worked for positioning but didn’t reckognize mouse clicks from the pen touch. If your’s does this too, simply open the control panel applet and toggle the settings to heavier then back to light. Experiment with these settings.

So there you have it. A cheap ass tablet, salvaged thanks to the fact that the semiconductor company who made it’s controller saw fit to put the information on the Internet for all to see.

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