RE: Space Duel Tech

Awesome tip Bill!  I'll take a look at the chip temps first! -Malcolm
--- On Sat, 9/19/09, Bill <sociableone@gmail.com> wrote:

From: Bill <sociableone@gmail.com>
Subject: RE: VECTOR: Space Duel Tech
To: vectorlist@vectorlist.org
Date: Saturday, September 19, 2009, 9:34 AM

A great first step that I use when I know there is an overvoltage stress is
to take all of the chips' temperatures to see if any have a "fever".  You
can do this by touch but BE CAREFUL and it's not as accurate, but you will
find the really hot ones.  I bought an infrared thermometer on clearance
from Radio Shack after burning my fingers one too many times.  Some chips
like rams and ASICs will tend to run hotter.  The nice thing about the
thermometer is that you can compare the temperature of two like devices on
the same board.  I used this technique recently with an asteroids board that
got whacked by a bad AR and identified all of the bad ICs by temperature.
This is not always the case but it is a handy weapon to have in your repair
arsenal.  After you do get the board repaired and working, you are not done.
Some chips may have been damaged by overvoltage stress but will not fail
immediately.  I cycle the board powered then unpowered for several hours
through a few cycles.

Bill

-----Original Message-----
From: owner-vectorlist@vectorlist.org
[mailto:owner-vectorlist@vectorlist.org] On Behalf Of
solarfox@triluminary.net
Sent: Saturday, September 19, 2009 8:47 AM
To: vectorlist@vectorlist.org
Subject: Re: VECTOR: Space Duel Tech

On Fri, 18 Sep 2009 23:35:04 -0700 (PDT), you wrote:

>Out of ideas, so I thought I'd ask about on this one.  Space Duel board was
working and then got a jolt from a failing ARII.  Initally had one high
tone, so I replace the first RAM, and was rewarded with two high tones. 
Replace the second RAM and the game played blind...for about 2 minutes after
which it gave me two short low tones, and two long high tones.  At this
point, I replaced the AVG chip, processor and Pokeys with no change. 
Stationary vectors on the screen, solid coin switches. 
> 
>The manual is no help with this tone combination.  I haven't switchd out
the ROMs yet as I don't have a reader to check them.   Anyone have any
ideas?  I do have a logic probe if anyone has anything specific for me to
test.   -Malcolm

    While I can't think of anything specific off the top of my head, I
would say this: don't get so focused on the "major" chips (CPU, Pokeys,
etc.) that you overlook the "little guys"; i.e. the 74LS-series logic chips
that glue all the big guys together.  74LS-series TTL chips, at least in my
experience, are *notoriously* intolerant of overvoltage conditions; that
failing AR-II may well have whacked one or more of them, in which case the
major chips may be working just fine, but not be able to communicate with
each other because some 74LSxx chip in between them isn't doing its job any
more.

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solarfox@removethis.triluminary.net                          (Gary Akins
jr.)
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Received on Mon Sep 21 12:34:19 2009