Re: Tempest problem.

Is /VMEM asserted when read/writing the vector ram 2000 -> 2FFF? pin5 B3 ?

H3 is your data buffer for all vector rom/ram, make sure its good (you may have already)

For an -02 pcb, W4 jumper should be installed, connecting C1 pin 14 to signal AM11 (K2 pin 4) this affects the reading of vector rom at 3000 -> 3FFF.

Half your problem might be that W4 jumper issue, but you say vector ram is also affected, check K2, L2, C3 and J5 (sheet 3 side A)

enjoy

Andrew Welburn
www.andys-arcade.com
  ----- Original Message -----
  From: Kevin Moore
  To: vectorlist@vectorlist.org
  Sent: Tuesday, November 17, 2009 1:55 PM
  Subject: Re: VECTOR: Tempest problem.

  I just wish the other tempest board I'm working on was as forgiving.

  It won't boot, something isn't right with the Vram, and Vrom addressing. Using the fluke I can read all the roms and check the normal game ram just fine. But can't read the vroms or do a mem check on the vram. The buffers appear to toggle just fine when trying to access with the fluke, (in normal game run they don't toggle at all) I went ahead and replaced them still no joy.

  It's a rev 2 board it looks like, and the w4, and w2 jumpers aren't present. So I'm still kinda at a loss.

  When I put it in test mode, I get one short low tone and nothing. Still probing around trying to figure out where the problem is..

  Kevin

  On Tue, Nov 17, 2009 at 7:48 AM, Andrew Welburn <andy@andysarcade.net> wrote:

    heh, those kinds of faults where you can kickstart a stuck node are very rare, i've done maybe 3 of them in 10 years, and only one of them later failed... one was on an asteroids, one was on a battlezone, and the other was on a more modern game i forget what it was, but it was that one i had to revisit and replace the offending IC.

    So i'd say you have a 33% chance of it re-appearing, but at least yuou know exactly where to look if it does re-appear.

    Andrew Welburn
    www.andys-arcade.com
      ----- Original Message -----
      From: Kevin Moore
      To: vectorlist@vectorlist.org
      Sent: Tuesday, November 17, 2009 1:37 PM
      Subject: Re: VECTOR: Tempest problem.

      Yeah, I just hit it with +5v and it started toggling. The problem hasn't come back even through power cycles. It's been running just fine for the past 12+ hours. Which seems odd to me, so I'm going to keep an eye on it for a while longer.

      Kevin

      On Tue, Nov 17, 2009 at 7:27 AM, <kstillinger@sc.rr.com> wrote:

        Hey Kevin-

         What exactly do you mean when you say you 'toggled' the pin?
         Did you force it high with a momentary short to 5V? If so, did it start making the appropriate transitions afterwards? Does the problem re-appear after power cycling?

         Just curious and looking for more info.

         Kerry

        ---- Kevin Moore <talon.k@gmail.com> wrote:
> Thanks Andrew. I have the alt circuit with the MC3410. Pin 4 was stuck low.
> Toggled it, and the problem went away. I'm sure the problem will come back,
> When it does, I'll have to check the proceeding circuit to see if the
> problem is with the 3410, or somewhere before. But at least I know where the
> problem lies.
>
> Thanks very much for pointing me in the right direction.
>
> Kevin
>

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Received on Tue Nov 17 09:10:27 2009