Fun with a DWUBA

From: Lawrence Walker <>
Date: Wed Mar 13 22:50:07 2002

 And here I thought it was a post about Bush Jr. George DWUBA.

> --- Gunther Schadow <> wrote:
> > Ethan, I'm glad to hear you are making headway in fixing your
> > fried board...
> I was up to my elbows in the 8200 last night. I think I've identified
> the target pin on the DD11DK that is the destination of the damaged pin
> in the first place - BB2 which is defined as a ground. This is odd because on
> the paddle card, the signal is individually routed over pin 30 of JP2 and is not
> tied to anything else on either end.
> Having inspected the cable carefully, multiple times, I'm still scratching
> my head as to how the damage could have happened in the first place. I
> had notes written right on the Unibus cables where they stick onto the
> back of the VAXBI - the notations match the docs (I have the DWBUA technical
> manual with installation instructions). I can't even see how putting the paddle
> card in backwards would have caused a massive problem. I'm afraid to hook
> everything up and power it on again before I identify what was wrong.
> OTOH, I did drop the T1010 card in the VAX and look for its presence on
> the bus. With the cables disconnected, the card fails self-test (Duh!)
> but when I go to read the ident register of the DWBUA (E 20000000), I
> get back FFFFFFFF, not the expected value (as documented in the manual).
> Having written VMS VAXBI drivers in the past, I can say that this is not
> good. The card "shows up" - the POST shows a "-0", so the VAXBIIC of
> the DWBUA is detected, but it's exceedingly unhappy. I am suspecting
> that the card is more fried than one chip. I'll keep working on it to
> see if the card needs a rudimentary amount of attachment to the UNIBUS
> to get far enough into its self-test to initialize the ident register,
> but I'm not hopeful about it - I think it should show the world what
> it is, even if it's unhappy.
> Fortunately, I have docs for all of this. At this time, I suspect the
> M9313 UET, the DD11DK, the cables and the T1010 card. I just have to narrow
> down the list of suspects. I suppose I could drop the card in with the chip at
> risk removed and a lead hanging out so I can monitor what's happening on that
> pin. The pin itself happens to go to the outer-most pad on the VAXBI bus,
> looking at the board, it's the farthest pad from the VAXBIIC on the solder side.
> It goes diagonally in more-or-less a straight line to a pin of a DEC DC021C, 4
> or 5, IIRC (it's not in front of me here). Either that pin sources a whopping
> amount of current from the DC021 and it was shorted to ground by a bad cable or
> a problem in the BA11, or somehow a very wrong voltage came from the BA11 into
> that pin. It's the only way I can see how a trace can get cooked and the chip
> melted at that pin.
> Back to the basement...
> -ethan
> =====
> Visit "The Seventh Continent"
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Received on Wed Mar 13 2002 - 22:50:07 GMT

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