Tech Needed: Outrun

[JCRS]

[ukvac] Tech Needed: Outrun

I have a problem with a mini outrun, the left hand side of the screen
suffers badly

see pic at http://www.pinckney.org.uk/outrunvdu.jpg the machine plays fine
except the corruption at the left hand side of the screen.. any ideas what
this could be ? cap ?

also the sound seems to be missing on channel.

I have ran the Test Switch and it passes all ROMS, although Rom 65 or 114
seems to put a small amount of snow on the screen for a split second and im
unsure if it suppose to do this. Any ideas anyone ?

Your help would be appreaciated...

thanks.

 

[P-Man]

Re: [ukvac] Tech Needed: Outrun
> I have a problem with a mini outrun, the left hand side of the screen
> suffers badly
>
> see pic at http://www.pinckney.org.uk/outrunvdu.jpg the machine plays
fine
> except the corruption at the left hand side of the screen.. any ideas
what
> this could be ? cap ?

umm, looks a little more worse than the left hand side of the screen

Look like RAM problem, or a ram buffer.

> also the sound seems to be missing on channel.

can't explain that one

> I have ran the Test Switch and it passes all ROMS, although Rom 65 or 114
> seems to put a small amount of snow on the screen for a split second and
im
> unsure if it suppose to do this. Any ideas anyone ?

sounds like graphics ram to me.. the snow is indicative of a screen ram
problem. if outrun is marginally similar to hang-on (i think its slighlty
the same then you should be looking for 2148 fast sprite screen
ram/buffer thingies...

> Your help would be appreaciated...
>
> thanks.

screen rams aren't often checked when running self test, and even if they
are, you can have games that pass the self-test, but do indeed have a bad
ram which confuses a lot of people

so ram, or ram-buffer, something to do with the screen ram i would think.

hope that helps.

Andy

 

[John Bennett]

Re: [ukvac] Tech Needed: Outrun
> > I have ran the Test Switch and it passes all ROMS, although Rom 65 or
114
> > seems to put a small amount of snow on the screen for a split second and
> > unsure if it suppose to do this. Any ideas anyone ?
> sounds like graphics ram to me.. the snow is indicative of a screen ram
> problem. if outrun is marginally similar to hang-on (i think its slighlty
> the same then you should be looking for 2148 fast sprite screen
> ram/buffer thingies...

It puts snow on the screen as it's testing the GFX RAM by filling it with
data. Snow is normal, as long as it then clears back to the correct picture
(and it'll say RAM OK too )

--Cas



DATA Imported from archives: originally posted by John Cassells (john@cassells.screaming.net)

 

[JCRS]

Re: [ukvac] Tech Needed: Outrun

Hi..

Ive had a look on the outrun pcb but cant find any IC's with 2148 on them..
Also the sound problem isnt a channel problem.. both channels play but half
the tune is missing.

Anymore help would be grateful..