Assembly Instructions

  1. Program the Atmel AT89S8252 microcontroller
  2. Populate PCB; see the parts list
    - R2, R20 may be zero-ohm resistors (or shorted with a wire)
    - R17, R36, C8, C16 provide optional amplifier peaking and should nominally be omitted
    - C6, C14, C57, C58 should also nominally be omitted
    - U30, U31 are footprints on the bottom of the PCB for optional unity-gain buffers.   If buffers are used, the trace connecting pads 2 and 4 (buffer output and   input respectively) must be cut.  C66-C69 are bypass caps for the buffers on the bottom of the PCB.
    - SMB PCB connectors should be used for J10, J11 (the main outputs).  For J1, J12 (sync outputs), SMB connectors may be used.  However, headers may be used instead of the expensive SMB connectors.  The extra holes in the J1 and J12 footprint are included so that a 4-pin header, spanning J1 and J12, may be used. 
  3. Prepare enlosure (see parts list for recommended box)
    front panel (outside, inside)
    cut holes for rocker switches, BNC connectors, LCD, pushbuttons, and rotary encoder.  Use the front panel label to align holes.
    - apply front panel label (postscript, Adobe Illustrator)
    rear panel (outside, inside)
    - cut holes for DIN power connector, DB-9, BNC connector, and toggle switch.   Use the rear panel label to align holes.
    - apply rear panel label (postscript, Adobe Illustrator)
    side panels
    - cut plate which will hold LCD, pushbutton matrix
    - attach right-angle brackets to plate for mounting to side panels
  4. Mount the pushbuttons on a piece of perfboard (0.1 inch hole spacing)
    The resistors that are in series with the row address lines should be mounted on this board (see the panel wiring diagram)
  5. Mount pushbutton perfboard and LCD to plate using metal spacers, attach plate to side panels
  6. Wire the front and rear panels.
    - Use a 3-terminal strip for local power and ground connections to the LCD and rotary encoder, and as a node for the power sense line.   Make sure to bypass the +5 power supply on this strip with a large tantalum capacitor.  Otherwise, large spikes will appear on the power line when the LCD backlight is switched on.
    - A 50 ohm termination resistor must be included as part of the reference select circuit
    - Use AMP-MODU style connectors to interface with PCB headers
  7. Set jumpers J5, J9, and J4.
    - J5 (serial programming header):  for normal operation, jumper pairs 1-2, 5-6, 7-8
    - J9 (sync driver enable):  for normal operation, jumper pairs 1-2, 5-6.  To disable sync drivers, jumper pins 2-4, 6-8
    - J4 (watchdog enable):  jumper to enable watchdog reset circuit


Modifications for one-channel version