Video Banding Modification
Video Banding Modification: Many (most?) A4000s show some faint vertical
bands on the display. There is a modification to prevent this, but, like
anything else, it has advantages and disadvantages.
Removes vertical bands from display.
Relatively easy to disable.
The modification involves connecting pin 15 of the video port connector
through a 100 ohm, 1/4 watt resistor to ground. This can be done inside
the A4000, but it's safer and more versatile if the modification is performed
on the DB23-to-HDD15 adapter that was included with the A4000. That way
the adapter can be unplugged from the machine if a genlock or Amber board
is to be used.
Interferes with operation of attached genlocks and deinterlacer boards
like the Amber A2320 board (see Boards/A2320 'Amber'
There are two grounds on the adapter PC board: shield ground and video
ground (pins 16-20). Since all the other components on the board use the
video ground, it seems reasonable to use it for this modification, rather
than the more-easily-reached shield ground. The resistor fits nicely on
the bottom of the adapter PC board, running from pin 15 to pin 18 of the
connector's soldered pins.