Powering up a 20-year old MicroVAX II (BA23/123 cables)

tiggerlasv at aim.com tiggerlasv at aim.com
Tue Feb 24 02:09:11 CST 2009

On Monday, February 23rd, Charles H Dickman wrote:

>> Robert Jarratt wrote:
>> The harness in my system does not seem to match any of the 
descriptions I
>> have seen so far. The wires are not equal in length, but it is not a 
>> cable with IDC connectors either. The connectors are black rather 
>> white. The harness wires do not seem discoloured, but I believe that 
>> particular system may have only had light use in its day. I have a 
>> of the harness but I am not sure if the rules of this list allow
>> attachments.

> The key point of your description is that the wires are not equal in
> length. This COULD be a bad thing.

On the BA23, the backplane and power supply connectors are at
right-angles to each other, so the 5-volt (red) wires are shorter
than the 12-volt (yellow) wires, as well as most of the grounds (black).

The same is true on the BA123.

As you can see in the ASCII art below, the 12v interconnect wires
end up being longer than the 5V wires.

This is normal.

I have a side-by-side photo of the old style cables, as well as the FCO,
however I don't have a convenient place to post it.   If anyone wants it
for reference, let me know.

 |   1
 |   2
 |   V
 |   G
 |   n
 |   d
 |   5
 |   V

         5 V       G n d        1 2 V
         _  _  _  _  _  _  _  _  _  _


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