TECH : Bally Eight Ball Champ

[Guest]

Archived from groups: rec.games.pinball (More info?)

Hi. I have a Bally Eight Ball Champ with an intermittant problem.
Usually, the game will boot up and run fine. After a period of time,
it will lock up. The playfield lights go out, but the score displays
and flippers still work. After another period of time, it will "wake
up" and continue to play from where it left off. Usually, the ball is
in the outhole at this time. It starts with the "you scratched" voice,
and kicks the ball into the lane.

I thought the problem may be heat related, and went after the MPU board
with a can of freeze. Sometimes, the game would start again, but other
times it would not. I had the same luck "thumping" the chips and
jiggling connectors. There was nothing consistant that I could find
that would bring the game back to life.

Sometimes, it will not boot from a cold start. I think I usually get
six or seven flashes. A few slow power off and on cycles will get the
game going.

I guess it's time to borrow an o-scope. Any suggestions on where to
start ?

Thanx.....don

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

Check crystal for activity- maybe there's no crystal for the CPU to run off
of...

Ray J.
--
Action Pinball & Amusement, LLC
Salt Lake City, Utah USA
Web: www.actionpinball.com

We're serious about pinball. Anything else is just for fun!



<Don_Shoemaker@HotMail.com> wrote in message
news:1120652256.892041.295220@o13g2000cwo.googlegroups.com...
> Hi. I have a Bally Eight Ball Champ with an intermittant problem.
> Usually, the game will boot up and run fine. After a period of time,
> it will lock up. The playfield lights go out, but the score displays
> and flippers still work. After another period of time, it will "wake
> up" and continue to play from where it left off. Usually, the ball is
> in the outhole at this time. It starts with the "you scratched" voice,
> and kicks the ball into the lane.
>
> I thought the problem may be heat related, and went after the MPU board
> with a can of freeze. Sometimes, the game would start again, but other
> times it would not. I had the same luck "thumping" the chips and
> jiggling connectors. There was nothing consistant that I could find
> that would bring the game back to life.
>
> Sometimes, it will not boot from a cold start. I think I usually get
> six or seven flashes. A few slow power off and on cycles will get the
> game going.
>
> I guess it's time to borrow an o-scope. Any suggestions on where to
> start ?
>
> Thanx.....don
>

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

You may have a RAM, (or PIA), problem which is causing the cpu to stall
while waiting for data. If the clock speed slows and the processor is
still running the game will run in slow motion. That really doesn't
sound like what you are describing.

If you know how to do it you can actually run the entire program step
by step, (although never in the game). Since it doesn't appear to go
into reset and start back up in the attract mode the cpu did not stop
operating, but is waiting. I used to check this by watching the
display interrupt, and using that as an indicator. The displays strobe
at a rate that is much easier to measure than clock speed.

You did not specify if they are updating. Just that they still work.
I have to assume you mean they are just lit with whatever number data
was last latched into the decoder. If that is the case, the PIA has
not updated, and could be holding up the show. This may be why it is
not always picked up in the POST.

We were shown that in a very rare case the hardware could hold a data
fetch and make the game appear hypnotized. It almost sounds like that
is what you have, from a PIA timing problem, or a RAM problem.

This was a common problem with in-experienced techs rebuilding the
clock circuit on Stern MPU's using the Bally parts values. Game ran
really slow, (Meteor). It was quite amusing until we fried the drop
target bank reset coil.

Mario
Pinthetic

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

I forgot to mention that the playfield lamps go out because they are
phased to the AC line. The SCR's have gone off at zero crossing, with
no new update to be turned back on.

Sorry,

Mario
Pinthetic

 

[Guest]

Archived from groups: rec.games.pinball (More info?)

Thanks to you, Ray and Clay for the feedback. I've inserted comments below.

In article <1120680831.479697.225450@g44g2000cwa.googlegroups.com>,
Pinthetic@gmail.com wrote:
>You may have a RAM, (or PIA), problem which is causing the cpu to stall
>while waiting for data. If the clock speed slows and the processor is
>still running the game will run in slow motion. That really doesn't
>sound like what you are describing.

It's been a while since I've done serious troubleshooting on this, but I think
I may have swapped the PIA chips. Clay suggested changing out the 5101.
I'll have to check to see if I have a spare one.

>You did not specify if they are updating. Just that they still work.
>I have to assume you mean they are just lit with whatever number data
>was last latched into the decoder. If that is the case, the PIA has
>not updated, and could be holding up the show. This may be why it is
>not always picked up in the POST.

The displays continue to show the last data they had (scores, ball in play and
credits)

>We were shown that in a very rare case the hardware could hold a data
>fetch and make the game appear hypnotized. It almost sounds like that
>is what you have, from a PIA timing problem, or a RAM problem.

I forgot to mention that board is in great shape, with what appears to be all
original chips. I'll keep poking around on it.

Thanks again.....don