Hi all, Hi Mark.
> For reference, this board is an implementation of what we refer to as
> the "CCPU" (Cinematronics CPU).
Yep. I understood this since some friend said my game looks like
Space Wars. He pointed me to Space Wars's pdf manual and I discovered
what is a "CCPU".
> Interesting. The board looks very similar to Rockola's CCPU
> implementation. Rockola also used a large edge connector in place of
> individual connectors. Cinematronics licensed this design to Rockola and
> apparently Sega as well. When I get time, I'll find out if it's
> coincidence they both use the edge connector or if the Sega design is
> descended from Rockola.
I'll be interested in this information.
William said it may be a bootleg by SEGA, but it would be surprising.
I may post this connector pinout if needed, if you want to compare it
to Rockola.
> It can be difficult, but it's a matter of understanding the system and
> applying the right methodology. I've been repairing those boards for 15
> years, and you get the hang of it.
This afternoon, while checking signals on RAMs, then "K" bus, then N2,
I discovered that there is a problem for sure on bit K1, maybe K3 and
K10 also. Either N2 (74LS257) is broken, either some chips set K1 to high.
Since it's currently 03:00 in the morning in France, I'll continue
checks tomorrow evening. ;-)
> > I can seen important glitches on some of the E14 PROM data bits.
>
> This is what we call a red herring. This is _not_ your problem.
Good to know this. I won't spend more time on it.
> At 2uS/div, your DSO may not be sampling fast enough to catch the
> complete transition to the opposite logic state, before the next
> transition begins. Remember, you're looking at the inside of a 5MHz CPU.
> Try 50ns/div or better and see how it looks.
I already tried at 200 ns/div.
Here is it : http://aquafab.free.fr/gamoover/all.png
My Fluke DSO goes as fast as 5 ns/div, but it's hard to catch the
exact interresting instant.
> You mentioned there were glitches, but didn't mention if the device
> contents were correct. If the contents are wrong, then I'd agree the
> part has a problem.
Up to now, I've only checked E14 content, which is OK.
I found a serious clue on K bus & N2 and it'll be investigated
in the next days.
> However, if you're seeing
> glitches, for example, on the output of F14, which drives _registered_
> logic, that would be a problem.
Good information too. I'll check it.
SEGA is using a Fujitsu MB7052 PROM for that chip.
> If you really want to test the prom devices, the best way for you to do
> so, is:
> 1) Substitution
> 2) Data contents validation (if subs aren't available)
I built my own PROM reader, but I need to manually set the address bits.
It's OK for a small 32 x 8 bits PROM, but much more boring for
a 1k x 4 bits device ! ;-)
> FWIW, I've never seen a prom in a CCPU that didn't work, but did have
> valid contents. Therefore, if you validate contents, the probability is
> very high that the device is good. Further, PROM failures on the CCPU do
> happen, but are statistically very rare.
That's interesting.
Of course it's not 100% sure, but I'll trust your experience.
What about RAM failures ? SEGA is using NEC µPD2101AL-2 chips.
> I'd offer to fix your board (see cinelabs.com <http://cinelabs.com>),
> but you indicated you'd like to fix it yourself. My advice would be to
> not do what many other people have done, which is to take a shot-gun
> approach, which makes the board look like a mine field, and frequently
> introduces more problems than it fixes.
I already fixed a lot of screens & PCB. I sometimes find some previous
tries to fix the problem that in fact made it bigger.
When I repair such old PCB, I want to keep then in good condition.
Shot-gun is forbidden.
> Hope that answers some of your questions.
Yes, merci beaucoup. :-)
> P.P.S. Is your control panel missing buttons? Space Wars has 10 buttons,
> used to start the game. I see them on the game flyer, but not in the
> picture of your actual game.
Yes and no.
My cabinet is a french version of SEGA Space Ship.
It looks like a conversion made in factory because it's very well done.
There is an instruction set in french which really seems to be original,
and not put there by the original game owner.
The control panel is in french and is above an other control panel,
written in english.
The english control panel can be seen at some place were the top control
panel is damaged.
The french control panel has :
- two 3-ways joysticks
- two "fire" buttons (one for each player)
- a "start game" button
- a "reset game" button (don't know what it does... surprise...)
There is no "hyperspace" button, no game choice button...
But, when I look from inside the cabinet, I can see a lot of square
holes in the english panel, which are covered by the top panel...
I'll take some pictures of this.
The game PCB has all the required inputs to handle all Space Wars
buttons, but most of the "choice" buttons are not available.
Regards.
Fab
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Received on Sun Jan 10 20:53:58 2010
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