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TECH: Frogger weirdness (graphics)

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Anonymous
July 28, 2005 6:20:15 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

Working on a Sega/Gremlin Frogger PCB that seems
to work fine, except for a vertical "graphics trash"
line about 4 or 5 characters from the right that
extends from the bottom of the screen about 1/2 or
2/3 of the way vertically up the screen. It's only
1 or 2 characters wide (think of the text on the
attract screen and that's the width I mean). It
doesn't affect many of the foreground sprites, but
a few of the floating items and the occasional
car is corrupted. The game is still fully playable
and the sounds are fine too. The graphics line is
always at the same place and never changes!

I swapped another working board and found the
problem is tied to the bottom PCB (video half).
I've replaced all of the 74LS20s, two PROMs at
the end (still working on the other 4, but I
pulled them before and even with them gone the
graphics line was still there), replaced the Z80C,
the ribbon cable and the 74LS04 that's socketed at
IC31.

Voltages are reading 4.94Vish at the RAM. I cranked
the voltage-up just to get there, but am getting
5.4 to 5.5 at the edge connector, so some voltages
are being lost on the sound board and ribbon cable.
I piggybacked the RAM as a test and it caused the
game to constantly reset after showing the all "X"s
screen. However, before it would reset it would
start to clear the screen (suggesting the game was
working) until it got to the area of screen where
the graphics trash line is. This happened every
time and once the Xs cleared the graphics trash line
could be seen.

Anyone have any ideas? I wish the RAM was socketed,
so it would be easier to replace to rule it out. I
am thinking this is suggesting a RAM issue, but
wanted to bounce it off folks here first.

Scott C.
Anonymous
July 28, 2005 7:17:42 AM

Archived from groups: rec.games.video.arcade.collecting (More info?)

I jumpered the +5v from the main harness onto the
bottom PCB (video PCB) so it got the same +5v as
the top PCB, but that didn't change anything. Also,
was able able to piggy-back the RAM (all 4 at one
time), but the graphics problem didn't go away,
which suggest the problem isn't RAM related. :( 

Scott C.

Scott Caldwell wrote:
> Working on a Sega/Gremlin Frogger PCB that seems
> to work fine, except for a vertical "graphics trash"
> line about 4 or 5 characters from the right that
> extends from the bottom of the screen about 1/2 or
> 2/3 of the way vertically up the screen. It's only
> 1 or 2 characters wide (think of the text on the
> attract screen and that's the width I mean). It
> doesn't affect many of the foreground sprites, but
> a few of the floating items and the occasional
> car is corrupted. The game is still fully playable
> and the sounds are fine too. The graphics line is
> always at the same place and never changes!
>
> I swapped another working board and found the
> problem is tied to the bottom PCB (video half).
> I've replaced all of the 74LS20s, two PROMs at
> the end (still working on the other 4, but I
> pulled them before and even with them gone the
> graphics line was still there), replaced the Z80C,
> the ribbon cable and the 74LS04 that's socketed at
> IC31.
>
> Voltages are reading 4.94Vish at the RAM. I cranked
> the voltage-up just to get there, but am getting
> 5.4 to 5.5 at the edge connector, so some voltages
> are being lost on the sound board and ribbon cable.
> I piggybacked the RAM as a test and it caused the
> game to constantly reset after showing the all "X"s
> screen. However, before it would reset it would
> start to clear the screen (suggesting the game was
> working) until it got to the area of screen where
> the graphics trash line is. This happened every
> time and once the Xs cleared the graphics trash line
> could be seen.
>
> Anyone have any ideas? I wish the RAM was socketed,
> so it would be easier to replace to rule it out. I
> am thinking this is suggesting a RAM issue, but
> wanted to bounce it off folks here first.
>
> Scott C.
Anonymous
July 28, 2005 3:48:51 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

The sockets on those boards are usually garbage....
Try replacing the sockets on the two graphics ROMs.

Matt

"Scott Caldwell" <lscottcaldwell@excite.com> wrote in message news:zhXFe.1641$oY.1035@newssvr25.news.prodigy.net...
> Working on a Sega/Gremlin Frogger PCB that seems
> to work fine, except for a vertical "graphics trash"
> line about 4 or 5 characters from the right that
> extends from the bottom of the screen about 1/2 or
> 2/3 of the way vertically up the screen. It's only
> 1 or 2 characters wide (think of the text on the
> attract screen and that's the width I mean). It
> doesn't affect many of the foreground sprites, but
> a few of the floating items and the occasional
> car is corrupted. The game is still fully playable
> and the sounds are fine too. The graphics line is
> always at the same place and never changes!
>
> I swapped another working board and found the
> problem is tied to the bottom PCB (video half).
> I've replaced all of the 74LS20s, two PROMs at
> the end (still working on the other 4, but I
> pulled them before and even with them gone the
> graphics line was still there), replaced the Z80C,
> the ribbon cable and the 74LS04 that's socketed at
> IC31.
>
> Voltages are reading 4.94Vish at the RAM. I cranked
> the voltage-up just to get there, but am getting
> 5.4 to 5.5 at the edge connector, so some voltages
> are being lost on the sound board and ribbon cable.
> I piggybacked the RAM as a test and it caused the
> game to constantly reset after showing the all "X"s
> screen. However, before it would reset it would
> start to clear the screen (suggesting the game was
> working) until it got to the area of screen where
> the graphics trash line is. This happened every
> time and once the Xs cleared the graphics trash line
> could be seen.
>
> Anyone have any ideas? I wish the RAM was socketed,
> so it would be easier to replace to rule it out. I
> am thinking this is suggesting a RAM issue, but
> wanted to bounce it off folks here first.
>
> Scott C.
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Anonymous
July 28, 2005 9:34:56 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

It's funny, but even with the two graphics PROMs
completely removed the video trash is still there
(the game continues to play). Therefore, it's
something else putting the trash in there. It's
the weirdest problem I've run across on a Konami
style PCB (I'm sure others have seen far worse).

Scott C.

Matt Osborn wrote:
> The sockets on those boards are usually garbage....
> Try replacing the sockets on the two graphics ROMs.
>
> Matt
>
> "Scott Caldwell" <lscottcaldwell@excite.com> wrote in message news:zhXFe.1641$oY.1035@newssvr25.news.prodigy.net...
>
>>Working on a Sega/Gremlin Frogger PCB that seems
>>to work fine, except for a vertical "graphics trash"
>>line about 4 or 5 characters from the right that
>>extends from the bottom of the screen about 1/2 or
>>2/3 of the way vertically up the screen. It's only
>>1 or 2 characters wide (think of the text on the
>>attract screen and that's the width I mean). It
>>doesn't affect many of the foreground sprites, but
>>a few of the floating items and the occasional
>>car is corrupted. The game is still fully playable
>>and the sounds are fine too. The graphics line is
>>always at the same place and never changes!
>>
>>I swapped another working board and found the
>>problem is tied to the bottom PCB (video half).
>>I've replaced all of the 74LS20s, two PROMs at
>>the end (still working on the other 4, but I
>>pulled them before and even with them gone the
>>graphics line was still there), replaced the Z80C,
>>the ribbon cable and the 74LS04 that's socketed at
>>IC31.
>>
>>Voltages are reading 4.94Vish at the RAM. I cranked
>>the voltage-up just to get there, but am getting
>>5.4 to 5.5 at the edge connector, so some voltages
>>are being lost on the sound board and ribbon cable.
>>I piggybacked the RAM as a test and it caused the
>>game to constantly reset after showing the all "X"s
>>screen. However, before it would reset it would
>>start to clear the screen (suggesting the game was
>>working) until it got to the area of screen where
>>the graphics trash line is. This happened every
>>time and once the Xs cleared the graphics trash line
>>could be seen.
>>
>>Anyone have any ideas? I wish the RAM was socketed,
>>so it would be easier to replace to rule it out. I
>>am thinking this is suggesting a RAM issue, but
>>wanted to bounce it off folks here first.
>>
>>Scott C.
>
>
>
Anonymous
July 28, 2005 9:34:57 PM

Archived from groups: rec.games.video.arcade.collecting (More info?)

First I'd check the pullup resistors on the video RAM
data lines. Then put your probe on there and make sure
none of them are stuck (and replace them if they are).
Don't bother trying to piggyback RAM... that's not
going to tell you anything.

Good luck.

Matt

"Scott Caldwell" <lscottcaldwell@excite.com> wrote
> It's funny, but even with the two graphics PROMs
> completely removed the video trash is still there
> (the game continues to play). Therefore, it's
> something else putting the trash in there. It's
> the weirdest problem I've run across on a Konami
> style PCB (I'm sure others have seen far worse).
>
> Scott C.
>
> Matt Osborn wrote:
>> The sockets on those boards are usually garbage....
>> Try replacing the sockets on the two graphics ROMs.
>>
>> Matt
>>
>> "Scott Caldwell" <lscottcaldwell@excite.com> wrote
>>>Working on a Sega/Gremlin Frogger PCB that seems
>>>to work fine, except for a vertical "graphics trash"
>>>line about 4 or 5 characters from the right that
>>>extends from the bottom of the screen about 1/2 or
>>>2/3 of the way vertically up the screen. It's only
>>>1 or 2 characters wide (think of the text on the
>>>attract screen and that's the width I mean). It
>>>doesn't affect many of the foreground sprites, but
>>>a few of the floating items and the occasional
>>>car is corrupted. The game is still fully playable
>>>and the sounds are fine too. The graphics line is
>>>always at the same place and never changes!
>>>
>>>I swapped another working board and found the
>>>problem is tied to the bottom PCB (video half).
>>>I've replaced all of the 74LS20s, two PROMs at
>>>the end (still working on the other 4, but I
>>>pulled them before and even with them gone the
>>>graphics line was still there), replaced the Z80C,
>>>the ribbon cable and the 74LS04 that's socketed at
>>>IC31.
>>>
>>>Voltages are reading 4.94Vish at the RAM. I cranked
>>>the voltage-up just to get there, but am getting
>>>5.4 to 5.5 at the edge connector, so some voltages
>>>are being lost on the sound board and ribbon cable.
>>>I piggybacked the RAM as a test and it caused the
>>>game to constantly reset after showing the all "X"s
>>>screen. However, before it would reset it would
>>>start to clear the screen (suggesting the game was
>>>working) until it got to the area of screen where
>>>the graphics trash line is. This happened every
>>>time and once the Xs cleared the graphics trash line
>>>could be seen.
>>>
>>>Anyone have any ideas? I wish the RAM was socketed,
>>>so it would be easier to replace to rule it out. I
>>>am thinking this is suggesting a RAM issue, but
>>>wanted to bounce it off folks here first.
>>>
>>>Scott C.
!