old 94 DRAC Info

[Programmer]

Scott--is the 95 DRAC modified the same way ?

Lyndon
----- Original Message -----
From: Scot Sealander <Sealand at clarityconnect.com>
To: gmecm <gmecm at diy-efi.org>
Sent: April 22, 2001 6:04 AM
Subject: 94 DRAC Info


> Bought a DRAC from a '94 S-10 on Friday. Not knowing for sure the little
> white box was a DRAC, I downloaded the DRAC2.pdf file on /incoming.  The
> pdf file refers to two different styles of DRAC, the 92-93 version, and
> the 94 version.  A lot of good info there, but not as much specific for
> the 94 version, as there is for the 92-93 version.
>
> This is some additional info for the '94 version. The 94 version is
> described as having redundant jumpers in the document.  These are not
> really redundant, but a demonstration of cost concious re-engineering.
>
> The individual pull-up resistors in the 92-93 version were replaced with
> one pull-up resistor in the 94 version.  Now the jumpers are there to
> either pull-up an input, or pull-down the same input, using just the one
> pull up resistor.  This means that the jumpers have to be installed as
> "mirror image" opposites.
>
> For example:
>
> Jumper loc on DRAC, edge of board, component side:
>
> 1 2 3 4 5 6 7 8   8 7 6 5 4 3 2 1
> | | | | | | | |   | | | | | | | |
>
>
> The first set (on the left, 1 to 8) is the pull down jumper set.  The
> second set (on the right, 8 to 1) is the pull up jumper set.  This means
> that if jumper 1 on the left is present, you cannot have a jumper on
> right number 1. Apply the same rule for all the other numbers.  If you
> mess this up, all inputs will be pulled down.
>
> You can get around this by jumpering the present single pull up
> resistor, and adding pull up resistors to the right side set of jumper
> positions, and then putting a DIP switch in for the left set.  This will
> make the 94 version like the 92-93 version.
>
> Thanks, Scot Sealander
> --------------------------------------------------------------------------
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