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Thread: Tektronix 4957 Option 02 graphics tablet - need schematic

  1. #1

    Default Tektronix 4957 Option 02 graphics tablet - need schematic

    I tried hooking my 4957 Option 02 graphics tablet to my laptop for testing - and smelled smoke from the tablet

    I looked at the PCB and saw the +12V and -12V tantalum capacitors were both burned.

    I unsoldered both caps from the top of the board using solder wick - as the back of the board (top of the digitizer) is a solid copper sheet soldered with heavy tabs in three places on two sides of the board.

    I checked the resistance to ground on the capacitor pads - and they looked ok.

    I soldered in a couple of 100uF 25V electrolytic capacitors, but another capacitor on the -12V rail started smoking.

    None of the components on the Option 02 board seem to match the 4957 service manual excerpt - that only includes a BOM for the original smaller 4597 tablet and mechanical pictures.

    If anyone has the 4957 service manual schematics and can post them - I should be able to get my tablet working again. It worked in 2001 when I bought it from an EBAY seller.

    Even the original 4957 schematic would probably help - although I suspect they changed the microcontroller design as the user manual that came with my tablet showed several command differences.

    Monty

  2. #2

    Default Tektronix 4957 Series Graphics Tablet - including Option 02 - User Manual

    I spent a couple of hours this morning scanning the user manual that came with my tablet - as it shows differences in commands between the original smaller tablet and the Option 02 tablet.

    Here is a link to my scan:

    070-4784-01_4957_Series_Graphics_Tablet_User_Manual_includi ng_Option_02

    Since this manual was dated Nov 1987, it only mentioned the 4050 series computers as compatible - and they removed the 4052 program that was in the original -00 user guide.

    I added those two Section 6 Programming pages into the -01 user guide in the link as it also gives instructions on using the 4010 terminals to test the tablet during terminal power up self test.

    Also the -01 manual describes changes in the commands between the original 4957 and the Option 02 version - including no AUTOBAUD - and you have three banks of DIP switches to configure the Option 02.

    Some of the differences are due to the different size, baud rates, etc:

    FUNCTIONAL CHARACTERISTICS

    RESOLUTION

    Stand-alone user selectable at 1,2,4,100,200,400,500, or 1000 points per inch.
    10, 20, or 40 points per mm (254, 508, or 1016 points per inch); or 4096 points
    across the entire active area. For the 4957, this is about 350 points per inch, and for
    the 4957 Option 02 it is about 228 points per inch across the X axis, and 341 points
    per inch along the Y axis.

    ACCURACY
    +/- .254 mm (.025 inch) nominal over active area.

    JITTER
    +/- 1 least significant digit.

    PROXIMITY
    12.7 mm (or .5 inch) nominal cursor distance above the active area of the tablet.

    REPEATABILITY
    +/- .254 mm (0.010 inch)

    SPEED
    The 4957 is sland alone user selectable at 2,10,30,45,60 or 90 X Y coordinate
    pairs per second. The 4957 Option 02 is stand alone user selectable at 1,2,5,10,
    30,60,75, and 80 X Y coordinate pairs per second.

    TABLET
    Size: The 4957 is 15.50" x 16.50" x .80" (393.70mm x 419.10mm x 20 mm).
    The 4957 Option 02 is 22.5" x 17.0" x .75" (571.5 mm x 431.8mm x 19.1mm)
    Weight: The 4957 is 2.7 kg (6 lbs); the 4957 Option 02 is 3.2 kg (7 lbs).
    Active Area: The 4957 is, 11.7" x 11.7" (297 mm x 297 mm);
    the 4957 Option 02 is 18" x 12" (441mm x 294 mm).


    Monty

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