Tech: Page Mr. Do! Tech expert

Archived from groups: rec.games.video.arcade.collecting (More info?)

Don,

Funny you should mention that. Keith is a regular here and has already
been posting about this problem.

Hope he's not mad at you for sending you a board to get fixed, only to
find you here asking the same things he was.

Don't know what type of relationship you have to/with him. But If he
sent you the board as a repair job, and finds you on his stomping
grounds asking the same questions he was; I would be feeling kinda
embarassed by now.

"he was sold the board with a
jamma adapter as tested and working 100%.
"

I think that might start something as it insinuates he was sold both
items by the same person. In fact IIRC the board was a feepay buy and
Mark Spaeth sold him the adapter.

Pull the schematics and start diggin through the sprite systems.

- Matt

Archived from groups: rec.games.video.arcade.collecting (More info?)

Sounds to me like a sprite ROM access problem. Can you see the bad
characters? (Monsters or whatever the heck they are)
I'm speaking from the hip here but if this board is anything like other
classics, there are 2 sets of graphic ROM(s): 1 for sprites and one for
tiles.
Looks like the tile ROMS are being accessed fine since you can see the
title screen etc. And the fact that you pass self test leads me to
believe that it's not a VRAM addressing issue.

-Adam
=================
www.onecircuit.com
=================

Archived from groups: rec.games.video.arcade.collecting (More info?)

Thanks for looking out for me Matt. Actually Don's local and we've been
swapping and buying stuff back and forth for a while so it's cool.

I did get the board on ebay and I have to tell you.. I can't imagine that a
problem like what we're seeing with this board all of a sudden happened in
shipping. Don mentioned some people plug a board in.. they see a title
screen and bam.. it's a "working board". So i guess that's why the ebay
seller won't do anything for me. "It was working when we tested it." To say
nothing of what that 'testing' consisted of.

I'm thinking that is the case with this board. Could this be a ROM issue? I
ask because I understand there's glass bubbles on the rom chips because you
erase them with some UV light. About 2 rom chips on this board had the glass
bubbles exposed (others had stickers on them). Is it possible for some code
to be partially erased even though the self test shows all is normal?

Also.. I mentioned there were some sound issues originally.. it turns out
that there is something up with the adapter I got from mark.. when i was
adjusting volume today my finger bumped the cap on the adapter and i got
considerable static.. gently tapping the top of the cap and then moviing a
little with light pressure caused more static and at some points stopped it
completely.

I'm thinking since it was shipped in a flat envelope.. maybe the cap got
mashed on a little in transit? We're going to de and re solder the cap which
should fix the adapter problem..

(note to mark.. maybe ship those things in a little box or something to
avoid this prob for other people. i'll take the hit on this one and fix it
myself so i don't have to send it back and forth to you.)

again.. if anyone has any ideas.. maybe even a spare set of mr do chips we
can try to swap, i'd appreciate it.

thanks.
k.




"Matty-t" <matthews@audio-doctors.com> wrote in message
news:1119128833.844608.262910@g44g2000cwa.googlegroups.com...
>
> Don,
>
> Funny you should mention that. Keith is a regular here and has already
> been posting about this problem.
>
> Hope he's not mad at you for sending you a board to get fixed, only to
> find you here asking the same things he was.
>
> Don't know what type of relationship you have to/with him. But If he
> sent you the board as a repair job, and finds you on his stomping
> grounds asking the same questions he was; I would be feeling kinda
> embarassed by now.
>
> "he was sold the board with a
> jamma adapter as tested and working 100%.
> "
>
> I think that might start something as it insinuates he was sold both
> items by the same person. In fact IIRC the board was a feepay buy and
> Mark Spaeth sold him the adapter.
>
> Pull the schematics and start diggin through the sprite systems.
>
> - Matt
>

Archived from groups: rec.games.video.arcade.collecting (More info?)

I don't charge Keith for repairs or anything. We just kinda help each
other out. He told me that someone said the problem may be voltage or
something stupid so I told him to drop it by. Most of the time problems
I've found are not the basic voltage or reseating problems that are the
usual answere to a problem though they are a good place to start. I'm
thinking theres probably a couple of problems with this board. The
first being sprite processing problems. The second being in the game
logic to process the status of the game. I usually don't get to far
into trouble shooting but if someone gives me specific ideas on certain
chips to change then I usually try that.

Thanks,
Don
NJ

--
Sent via Gamer Newsgroups
http://www.gamernewsgroups.com

Archived from groups: rec.games.video.arcade.collecting (More info?)

Have you done the self test yet?? Mr Do will run with corrupted or missing
roms. I had a problem like this and it turned out to be a bad rom socket.
Anyway, hold the player one and player two buttons down when you turn it on.
It should do a self test. Might show up a rom problem.



"ajcrm125" <ajcrm125@gmail.com> wrote in message
news:1119136878.102151.117570@o13g2000cwo.googlegroups.com...
> Sounds to me like a sprite ROM access problem. Can you see the bad
> characters? (Monsters or whatever the heck they are)
> I'm speaking from the hip here but if this board is anything like other
> classics, there are 2 sets of graphic ROM(s): 1 for sprites and one for
> tiles.
> Looks like the tile ROMS are being accessed fine since you can see the
> title screen etc. And the fact that you pass self test leads me to
> believe that it's not a VRAM addressing issue.
>
> -Adam
> =================
> www.onecircuit.com
> =================
>

Archived from groups: rec.games.video.arcade.collecting (More info?)

Yeah. I believe Don said he ran this and everything came up good.
Since I have no idea how this board was stored.. for all I know it could
have been on a shelf under a window that got a few hours of sunlight a day.

If the problem turns out to be a code issue and not a physical damage issue
I think I'd have a bit of a cause against the ebay seller who listed the
board as 100% working.. unless anyone thinks a code issue could be caused by
shipping. If they listed it as "working" then yeah... they may be able to
say.. 'it booted up.. so it was working'. 100% working though means no
problems at all and an "all sales final" note in the description shouldn't
absolve them of misrepresenting an item.

k.


"VaxX" <geoff_gunn@hotmail.com> wrote in message
news:42b55029$0$257$61c65585@uq-127creek-reader-03.brisbane.pipenetworks.com
..au...
> Have you done the self test yet?? Mr Do will run with corrupted or missing
> roms. I had a problem like this and it turned out to be a bad rom socket.
> Anyway, hold the player one and player two buttons down when you turn it
on.
> It should do a self test. Might show up a rom problem.
>
>
>
> "ajcrm125" <ajcrm125@gmail.com> wrote in message
> news:1119136878.102151.117570@o13g2000cwo.googlegroups.com...
> > Sounds to me like a sprite ROM access problem. Can you see the bad
> > characters? (Monsters or whatever the heck they are)
> > I'm speaking from the hip here but if this board is anything like other
> > classics, there are 2 sets of graphic ROM(s): 1 for sprites and one for
> > tiles.
> > Looks like the tile ROMS are being accessed fine since you can see the
> > title screen etc. And the fact that you pass self test leads me to
> > believe that it's not a VRAM addressing issue.
> >
> > -Adam
> > =================
> > www.onecircuit.com
> > =================
> >
>
>

Archived from groups: rec.games.video.arcade.collecting (More info?)

Keith in NJ <winner@soulshot.com> wrote:
: Yeah. I believe Don said he ran this and everything came up good.
: Since I have no idea how this board was stored.. for all I know it could
: have been on a shelf under a window that got a few hours of sunlight a day.
:
: If the problem turns out to be a code issue and not a physical damage issue
: I think I'd have a bit of a cause against the ebay seller who listed the
: board as 100% working.. unless anyone thinks a code issue could be caused by
: shipping. If they listed it as "working" then yeah... they may be able to
: say.. 'it booted up.. so it was working'. 100% working though means no
: problems at all and an "all sales final" note in the description shouldn't
: absolve them of misrepresenting an item.

There's a mux right in front of the color proms that selects sprite or
background data... I bet you'll find it's always selecting background  

--
Mark Spaeth mspaeth@mtl.mit.edu
50 Vassar St., #38.265 mspaeth@mit.edu
Cambridge, MA 02139
(617) 452-2354 http://rgvac.978.org/~mspaeth