Doug IIRC I'm fairly sure the battery doesn't need to be in place to check
the BBU Ram. I've only had about 50% success getting acid damaged boards
working with a HSS functioning.
You're other issue. I'm not so sure about. I assume you are working with a
solid monitor.
Kevin
On Fri, Aug 31, 2012 at 10:45 AM, Douglas Gauck <douglas@gauck.com> wrote:
> Hi all,
>
> I am finishing up the reproduction main board for Omega Race and after
> finding a few missed traces both the program and vector sides are running.
> I have two problems remaining: self test passes all but the darned BBU RAM,
> and I have jumping vectors:
>
> http://www.gauck.com/arcade/reprOR/testing/IMG_4042.MOV
>
> Drawing was better (but not perfect) up until the time I was testing
> voltage at RAM H1 and slipped. Killed one of the VROMs. Interesting
> problem, easiest to analyze on a text screen... the first letter in the
> line of text is fine, then as more vectors are drawn they get further out
> of alignment. And they move - not a static misalignment - jumping up and
> down and side to side. Does it with graphics and on the test screens but to
> a lesser extent (since there are fewer vectors in test).
>
> Seems as if when the state machine first loads new coordinates, all is
> well, but then starts losing track of where the beam is.
>
> I swapped out all RAM, the latches (273s), the multipliers (7497s),
> counters (191s), the multiplexers (157s), and the flip-flops (374 / 174s).
> Yay sockets. It sure seems digital to me, but what's left?
>
> The BBU would also be nice to solve. It doesn't work on any of my original
> boards either. Haven't really dug into that one but if anyone has one that
> does work, is the battery required in circuit to pass self-test?
>
>
> -Douglas---------------------------------------------------------------------------
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Received on Fri Aug 31 12:58:08 2012
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