Re: I-Robot questions/answers and Tempest
- From: tim@xxxxxxxxxxxxxxxxxxxx <tim@xxxxxxxxxxxxxxxxxxxx>
- Date: Tue, 29 Nov 2005 22:16:43 GMT
In <1133234492.094163.287600@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> gregbot wrote:
> I have an original, arcade I, Robot in pretty much mint condition.
> Externally anyway. Gameplay, i get some 1/2 dozen white lines
> horizontally across the screen (sorry, don't know s**t for
> hardware/electronics) and as soon as u go into gameplay the robot
> falls into a black hole. Anyone know what the deal is? I may want to
> sell it, or maybe fix it for myself. Should i fix it before i try to
> sell it.
>
> Answer to an old question: I, Robot was 1984, it's in my original docs.
>
> On a semi-related note, my Tempest needs a power supply, i think.
> Where can i find one a them jobs?
>
> Thanks.
>
>
The white lines are due to bad video RAM. The 4164 video RAM is soldered
in on I, Robot, so you have to de-solder it (and preferably install
sockets) to replace it. If you're going to do it, you might as well
replace it all since they'll all go bad eventually. Since the originals
are hard to find you can plug in more modern 41256 chips instead for
longer life.
The black hole problem is most likely a low +5. The wiring harnesses on
I,Robot are not adequate to carry the amount of current the PCB draws so
they run hot, burning the edge connectors, which exacerbates the problem.
The quick fix is to turn up the voltage, but if you want to keep the
game healthy for a long time, replace the ground and +5 wires with
thicker ones and use contact cleaner on your edge connector to remove
the carbon build up. When you're done, test your cleanup/retrofit job
with your volt meter on ohms setting. Put one lead on the upper right (
with the notch facing up) pin of any EPROM on the PCB and the other lead
on the +5 output of the power supply. The lower the resistance number
you get, the better job you did. I won't hurt to do a before and after
to see the results.
The next most common problem on I,Robot are the mathbox EPROMs. Might as
well replace them now if someone didn't already do it. If there are
masked ROMs used for 101-104, then reburn them with regular EPROMs. When
they go bad, your polygons will go nuts.
Tim
.
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- I-Robot questions/answers and Tempest
- From: gregbot
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