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.


Disadvantages 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.

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.