Re: Tech: How to improve stationary target performance on early Bally SS machines?????

On Mar 1, 1:49 am, RJBAudio <ro...@xxxxxxxxxxxx> wrote:
On Mar 1, 1:40 am, homebrood <homebr...@xxxxxxx> wrote:



On Mar 1, 12:22 am, RJBAudio <ro...@xxxxxxxxxxxx> wrote:

I'm in the process of restoring our 1977 Bally Evel Knievel machine.
We've had it since 1982 and after a while it became the forgotton
machine in terms of repairs.  I've replaced some SCRs, transistors and
coils and now have it fully functional electrically (really all that
was wrong was some lights didn't work and the extra chime never
worked, and boy is it nice to hear all of the notes in the melodies....
that start game melody always left us hanging for the last low
note!)

Anyway, there is one thing that I would like to try to address and it
is an issue that we've always had with this machine.  If any of the
stationary targets are hit too hard and too fast then they don't score
(the switch contacts are clean, by the way).  This is especially true
with the red "super" target in the middle of the playfield because a
direct hit from the flippers hits it pretty hard and fast, and it only
scores a fraction of the time.  I suspect that part of the problem is
that the duration of the contact between the switch tabs is too short
for the processor to recognize it as a hit.

My question is, are there any mods that can be done either physically
or electronically to improve the sensitivity of this switch in any way
that will make the processor recognize a really hard and fast hit?

Theses switches have a diode on them but they should also have
Capacitors .047 value across them. Many ops clipped them off because
they became shorted as bally used crappy caps. The swithches will
still work but will miss quick closures. If you insall the capacitors
on these switches they will recognize quick closures and wont miss
scoring like that. Basically the .047 cap should be soldered to each
leaf of the switch or across the switch to bridge the contacts.
This won't short the connection it will just allow the cap to hold the
charge of the hit for a split second telling the MPU that the scoring
should be counted...

Tom- Hide quoted text -

- Show quoted text -

Thanks for the reply Tom.  I'll have to take a look inside and see
what is there.  I did notice some caps on a set of spare targets that
I got from a parted machine a while back, but there were two different
values used between the different targets.  I wonder if there is an
optimal sized cap for the best performance.  I'll have to go back and
read the values on them, but more importantly see what is on the
current targets installed in my machine.

Just go with the value cap it's supposed to have or higher. I've used
slightly higher ones without any problems.
.

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