Re: Using low power schottky IC's in System 1

Ed and all,

I agree, access / operation speed is probably a concern.

I friend had two "noisy" games, both Bally: 1978 "Paragon" and
1981 "Centaur". So, as sadly seems the norm here, he started
"working" on the soundboards. He replaced every Cap and IC for
which he could find a replacement. The noise from the speakers was
still there, but now he had the added bonus that some if his sounds
didn't work. I verified proper voltages and continuity on the boards.
We replaced "older" chips with the chips my friend had just swapped
out and all of the sounds could now be heard again. As for the
"hissing" speakers, we made sure that his boards had good grounding
and the noise went away.

I also had a similar problem with a 1984 Bally, "Black Pyramid".
But, this game had a "memory" problem. At the time, all I could
find was a: super expensive, radiation hardened, fast (50 nSec),
ceramic package 5101. Yep, the RAM was a 5101 for use in outer space. I
put the RAM in the "Black Pyramid". The game now seemed to work
fine, but the scores would NOT be held in memory with a power cycle.
So, I swapped the "space" 5101 with the old 5101 from my 1979,
Stern "Dracula". And, both games worked flawlessly.

The only thing I could conclude from both repairs was that timing was a
factor.

--
PinTed


GPE wrote:
> A definite -maybe-.
> The part speeds shouldn't be a factor, you will need to find the high and
> low load currents on the devices and then see if the parts you intend to
> substitute with are compatible. That would be tough to do with some of the
> parts as none of the rockwell parts have available data sheets anymore.
> That's probably why nobody has bothered to come up with a list of
> substitutable parts on the CPU board.
>
> -- Ed
>
>
> "BradandPam" <bradandpam@xxxxxxxxxxxxxxxx> wrote in message
> news:43cdb5bb$1@xxxxxxxxxxxxxxxxxxxxxxxxx
> > Can the low power schottkys be used as an equivalent replacement for all
> > IC's used in gottlieb sys 1's?
> >
> > eg. original 74175 chip can be replaced with a 74LS175
> >
> > but can the 7404, 7405, 7408 be replaced with a 74LS04 etc?
> >
> >

.

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