Re: Major Havoc help (was: Vectrex on Vector Monitor?)

I'm somewhat of a beginner myself - but with the help of others, I've been
able to fix about 10 games this past year - many of them being vectors.
One conclusion I've come to is - if you're going to attempt fixing a game
yourself, always get the schematics or a copy of them. They will
generally show you the pinouts of the CPU or map out the reset circuitry.
That way, it might be less confusing when someone hands out advice.
Depending on the game - you can usually find someone with a service manual
w/schematics for about $17 + shipping.

If you've already done this, then just ignore me. :)

Matt

_____________________________________________________________________

On Thu, 29 Oct 1998, Mark Jenison wrote:

> Clay,
>
> I've been keeping this e-mail around as debugging tips, but I realized that I
> have NO IDEA on how to actually do the things you mention. See my
> question/comments below...
>
> On Aug 12, 10:56am, Clay Cowgill wrote:
> > Subject: RE: Major Havoc help (was: Vectrex on Vector Monitor?)
> > > >quit reading it after arguing with some twit for far too long about
> > > 6809
> > >
> > > "twit" huh? Not very nice :)
> > >
> > :-) *grin* I probably should've put a smiley in there, but I was
> > typing fast before a meeting... ;-)
> >
> > > Speaking of twits, I have a couple MH boards I would like to resurrect
> > > from the grave. Board repair is not my specialty, but I have the
> > > capabilities to do it. Anybody have some tips/Atari signature guide/
> > > anything to help me with this task?
> > >
> > What kind of problems are they exhibiting? I've had good luck fixing
> > vector boards just starting at the crystal and tracing through the game
> > with nothing fancier than a logic probe. (A LOT of vector boards are
> > "resurrected" just by replacing a dead crystal, IMHO.) Just step
> > through it logically:
> >
> > Is the clock running? (check crystal and clock on microprocessors)
>
> Which pin is the clock on microprocessor, assuming Z-80? assuming 6809?
>
> > Is the board coming out of reset? (check watchdog outputs and reset
> > pins)
>
> Which pins are reset pins?
>
> > Does it look like the processor is running? (check datalines and address
> > bus for activity)
>
> Which are data lines?
>
> > Is it doing something useful? (see if chip selects on multiple ROMs are
> > occuring)
>
> What/where is chip select?
>
> > Is the Vector generator running? (check the signals in the vector
> > generator-- "GO, Reset, etc." is it hitting the Vector generator ROM?
> > Is the vector generator ASIC good?)
>
> Huh?
>
> > Are the DACs getting input data?
> > Are the DACs generating output voltages that make sense?
> >
> > I find the majority of problems in the clock circuit, followed by the
> > vector generator (usually after the DAC outputs), and then the program
> > ROMs....
>
> I think this is all good advice in general, but us dummies who don't have
> volumes of computer chip books (I don't even have ONE) could use some herding
> in the right direction...
>
> Thanks! (PS. When do Multi-pac's start shipping again? I haven't received
> mine yet...).
>
> ----------------------------------------------------------------------
> Mark Jenison E-mail address: jenison@cig.mot.com
> Cellular Infrastructure Group Motorola--Arlington Heights, IL
> ----------------------------------------------------------------------
>
>
Received on Thu Oct 29 16:54:37 1998