RE: Major Havoc Screen problems

Phew ok... Here goes more data gathering input (and I thank everyone that is
helping me AND all the people that are putting up with me!).

1. PCB Pots are reasonably accurate.
2. It appears that this scaling issue appears on each axis (got around that
plural thing)
3. Mathbox scaling seems to be a good guess since:
   a) when I go to the scaling display in test mode, that box that shrinks
does not do so smoothly, rather the box literally "appears" at different
sizes and then disappears. There is no smooth scaling anymore (there did
used to be).
   b) Also, I noticed that when I play the game, the movements are all jumpy
and the objects seem offset from what they should be and also appears that
there is some "slow-down in the game" where there wasn't before (like
shooting alien ships in the in-between sequence). Not only that, but it
appears jumpy (ie. when I am moving the ship left-right while shooting at
the aliens, it literally is Jumping to the next location rather than
smoothly moving.

        Parts of it are fun to track down the problems, but I need help in
identifying specifically where I should be looking for these things. Once I
have a starting area, I am usually cool with taking the time to analyze. If
it is the mathbox scaling, where should I be starting to look to track this
sucker. Could this be ROM corruption?

On the subject of the second board, when it doesn't work, it doesn't seem to
do a damn thing. No display, spot killer on (makes sense since no video
appears to be going to my WG). I tested all the voltages on the board and
the correct levels are making there way to the right places. No sounds, no
video, no nothing. Voltages ok. Puzzler.

Thanks
Andy

-----Original Message-----
From: Jon Raiford [mailto:raiford@mindspring.com]
Sent: September 7, 2000 09:16
To: vectorlist@synthcom.com
Subject: RE: VECTOR: Major Havoc Screen problems

At 09:23 PM 9/6/2000 -0400, you wrote:

> Hi Jon,
>
> It does not appear to be the HV unit. I took that over to my
friend's house and plopped it right into his and presto no problem. Also,
my MH was not exhibiting blooming as I understand it. I didn't *really* see
any magnifying glass look, rather it had looked like I took my x and Y size
pots and adjusted them such that my game now displayed information well off
the screen. There was no distortion in the images. Rather it was just like
someone had scaled my picture up in size and I was only seeing some of the
game on the screen. No mater how much I tried to reduce the screen size,
there was a limit and text, scores etc were off the screen.
>
> Any ideas as to what is wrong with my MH board? Could this be caused
by the deflection board? I am gonna try to replace this one as well to see
if I get the same symptoms, but I don't know that my monitor would display
these types of symptoms if it was a monitor problem.
>
> Anyhow, if anyone has any information that might help me, I would
appreciate it.

The deflection board could be the cause of it, but I doubt it. Your best
bet would be to test your pcb in you friends cab :) If the problem is in
the pcb, I would make sure the pots are good and maybe rebuild the vector
output section (TL082's & MC1495's).

Do the symptoms appear on both the X axis and the Y axis? If so, it could
be a problem with the mathbox scaling - it seems odd that the same parts
would go bad in both axis/axes (damn.. how the hell do you spell the plural
form?) Anyway, this is something that is not fun to track down (well, I
think its fun, but its certainly not easy).

> Since I am on the subject of Major Havoc, I have another boardset that
is giving me different problems. This one seems to have stopped working on
me... sort of. It was working fine and then it stopped working, or rather
started working interemittedly. At first I thought it may be a connector
problem or a trace problem, but the connector worked fine for my other MH
boardset no matter how many times I connected or disconnected it. THis
*bad* boardset would sometimes not work and I would disconnect, re-connect
the connector many times plug it in, unplug, move the board around...
sometimes this worked other times no go. There really didn't seem to be any
correlation between me connecting/moving the board to when it would work vs
not work. I cannot figure it out. Could it be a questionable capacitor
somewhere or transistor? Also, while this board was actually working, I
would jiggle the connector or press the board in various places (with a
piece of wood) and it did no!
t cause the game to stop, reset or do anything funny. It was on for the
long haul which makes me also believe that it was not a connector or bad
trace issue.

Sounds like you need to attack that board with an eraser. What does it do
when it doesn't work? Anything? Are the voltages ok on the board?

Jon

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Received on Thu Sep 7 09:22:58 2000