Instruction Manual - PDF - 2.4MB - 61 pages
Schematics - PDF - 0.3MB - 9 pages
Individual Schematics in JPG format (approx. 500KB each page):
Photographs
Changing from 20mA to EIA RS-232 serial output
Board-C contains two jumpers for changing the serial output from 20mA current output to EIA RS-232 output.
To select the EIA option, install the jumper from U3-4 (74LS04) to the 4K7 resistor. Remove the jumper from U3-3 to 4K7 resistor.Install the jumper from 3K3 resistor to -12V. Remove the jumper from the resistor to GND. See photo.
Changing from 1200 to 4800 baud
Serial output is on DB-25, pin-1 and GND is pin-25. Normal baud is 110. To change to 1200 baud, jumper pin-14 to GND.
To change the 555-timer circuit from 1200 baud to 4800, modify Board-E as follows. See photo.
If an extender card is not available, apply +5V to the board and adjust 1200B-ADJ trimpot for 76.8KHz output at 555-timer U32-3.
Data Loss
Incidences of data being lost have been experienced when the HORIZONTAL switch is changed from 1/2 to 2/2. An attemp to fix this problem involves a minor modification to Board-C.
2004.02.17
2014.07.22