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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.

Advantages

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.  


Copyright 2000 Amiga Auckland Inc. All rights reserved.
Revised: June 17, 2005.