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Technical Support Note
 

Product(s) involve	:	Video Blaster

Third party product(s)	:	Western Digital WD90C31 Local Bus SVGA

 

Subject

No display output on the monitor (black screen) after installing Video Blaster 
with machines using the WD90C31 Local Bus SVGA card.

Description

User will not be able to see any display on the monitor after connecting the 
Video Blaster to the VESA feature connector on the WD90C31 Local Bus SVGA 
card.

This problem occurs because the layout of the feature connector on the Western 
Digital WD90C31 Local Bus SVGA does not follow the specification define by 
VESA.  The location of Y-pins and Z-pins are reversed on the connector side.  
For example:

Normal VESA connector

Y-pins are located at the bottom row of the feature connector.
Z-pins are located at the top row of the feature connector.

WD90C31 Local Bus SVGA connector

Y-pins are located at the top row of the feature connector.
Z-pins are located at the bottom row of the feature connector.

Although the Z and Y pins labels are printed correctly on the PCB, however, the 
actual pin assignment are reversed and misleading as the Y1 and Z1 does not 
correspond to the actual pin 1 (which is normally grounded) on the connector.

Solution/Action

As there is no hardware patch for such design problem, the only solution is to 
use another SVGA card that has feature connector conform to the VESA 
specification until/unless WD redesign/relayout their feature connector pin 
assignment.

