Re: omega race hig score save

Resistors were pretty good.. I put in one closer to 1K (original was like .985 or something like that) and no dif.. I dunno.. do you think something in the cab could do this? I don't see how 3 pcb sets could do the same thing..

--- On Mon, 11/3/08, William Boucher <boucher@mnsi.net> wrote:

> From: William Boucher <boucher@mnsi.net>
> Subject: Re: VECTOR: omega race hig score save
> To: vectorlist@vectorlist.org
> Date: Monday, November 3, 2008, 7:02 PM
> Did you change the 5101 socket? I'm reaching now. It
> sounds like you've really covered everything but
> there's obviously something missing.
>
> I was thinking about something someone said previously
> about treating this 5101 like an eeprom when it is in fact a
> ram. It is addressed, read, and written on the standard but
> so "caching" its data in some sort of "main
> ram" makes no sense because whenever you want the data,
> it can be read from its address inside the 5101 just the
> same and just as easily as from a 2114. That said, it makes
> sense to assume that when you go into your test mode
> (without powering down) and you can see your high score
> there, that it is in fact being read out of the 5101. If it
> is writing and reading like that, then all of the logic
> chips must be working properly.
>
> That means that this problem falls all the way back to what
> exactly happens when the system powers down. Obviously, the
> data is getting corrupted. It may have something to do with
> all of those discrete components that control the chip
> select pin (pin 17). I suspect that pin 17 should fall to a
> logical low (to disable the chip) before the other pins
> (such as /wr pin 19, /batram [CS2] pin 20) fall. If they
> fall first, the chip will write and it'll save garbage
> to who-knows-where since the address and data lines are
> dropping like flies. The result would be a chip that
> contains data with a bad checksum or CRC and the next time
> that the game powers up, it would detect the error and
> initialize the data space.
>
> Check R150 [1k]. If it is open, this will cause the
> failure mode that I just described because it'll
> drastically raise the voltage at which the transistors
> [Q102,103] turn off causing them to stay on too long. Also
> check R143 [24k] for an open. Check Q102 [2N4403] and Q103
> [2N3904]. If either one is shorted, this will also cause
> the same problem because it keeps the chip enabled after
> powerdown..
>
>
> William Boucher
> ----- Original Message ----- From: "andre"
> <livnfree_can@yahoo.com>
> To: <vectorlist@vectorlist.org>
> Sent: Monday, November 03, 2008 9:18 AM
> Subject: Re: VECTOR: omega race hig score save
>
>
> > Actually, I had replaced KJ9 as well.. forgot to write
> that down..
> >
> >
> > --- On Mon, 11/3/08, William Boucher
> <boucher@mnsi.net> wrote:
> >
> >> From: William Boucher <boucher@mnsi.net>
> >> Subject: Re: VECTOR: omega race hig score save
> >> To: vectorlist@vectorlist.org
> >> Date: Monday, November 3, 2008, 8:06 AM
> >> JK6 doesn't appear to have anything to do with
> the 5101
> >> problem. You might want to try replacing the
> 74LS367 buffer
> >> at KJ9. It generates /mreq signal. Boy, this
> one is
> >> proving to be a real bear to track down. I wish
> you lived
> >> closer. I could bring over my Tech-Tools Digiview
> logic
> >> analizer and clip it onto the 5101, run the game
> once and
> >> then we'd see exactly was or was not
> happening.
> >>
> >>
> >> William Boucher
> >> ----- Original Message ----- From:
> "andre"
> >> <livnfree_can@yahoo.com>
> >> To: <vectorlist@vectorlist.org>
> >> Sent: Sunday, November 02, 2008 7:02 PM
> >> Subject: Re: VECTOR: omega race hig score save
> >>
> >
> >
> >
> >
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> >
>
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Received on Tue Nov 4 00:30:09 2008