Upside Down Galaga Image (part of the time)

wontwa

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Found some back threads related to this, but no definitive answer.

Just picked up a Galaga board from a fellow member, and when the game boots I got a "RAM OK, ROM 01" Error. This error displayed correctly upright. Pulled the chip at 3N, cleaned the legs, reseated, and now the game boots with the RAM/ROM OK in the correct position, then the scrambled carpet and grid and the game image is flipped upside down. You can credit up the game and play (upside down). Due to the original words displaying properly, I'm reluctant to mess with the yoke wires. Any idea where to look on the board to resolve this?

Thanks!
 
Here's a few photos of the issue. If anyone has any experience with this, any help would be greatly appreciated:
 

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And you're sure it's not running in cocktail mode? If you start a 2 player game, does the screen flip around for the second player?

This game selects cocktail mode by grounding a pin on the edge connector. But, whatever chip handles that input might be screwed up. Just a thought.

-Ian
 
Thanks for the reply! Just started a two player game and Player 2 remains upside down as well, so that doesn't appear to be the culprit.
 
It looks like the 00xx Namco custom chip at 1L has a flip pin. Can't tell from the schematics if that is an input or output though.

Try cleaning the pins on that chip VERY CAREFULLY! Just pulling those custom chips from their sockets can break the pins. :-(
 
Found some back threads related to this, but no definitive answer.

Just picked up a Galaga board from a fellow member, and when the game boots I got a "RAM OK, ROM 01" Error. This error displayed correctly upright. Pulled the chip at 3N, cleaned the legs, reseated, and now the game boots with the RAM/ROM OK in the correct position, then the scrambled carpet and grid and the game image is flipped upside down. You can credit up the game and play (upside down). Due to the original words displaying properly, I'm reluctant to mess with the yoke wires. Any idea where to look on the board to resolve this?

Thanks!

The errors and check are supposed to upside down
 
The errors and check are supposed to upside down

That's right! I forgot about that!

So that would mean that whatever is controlling the screen flip is just backwards somehow. I mean, I'm also assuming here that the OP knows that the monitor is already set up correctly for a Galaga... Might just have to swap the yoke wires :)

Is this a real Galaga cabinet? Have you seen another board work correctly?

-Ian
 
what if it's just the monitor yoke plug reversed? lol

I KNEW about the upside down check screen when you power on, I was barely awake when I saw this though lol
 
if the yoke wire was reversed the ram/rom text would be upside down as well.

It is upside down from what it's supposed to be...

When you boot a Galaga, the RAM/ROM test results are displayed for a second - upside down. Then the picture displays right side up for the game mode.

I'd forgotten about that until Jlannoo pointed that out.

-Ian
 
humm

It is upside down from what it's supposed to be...

When you boot a Galaga, the RAM/ROM test results are displayed for a second - upside down. Then the picture displays right side up for the game mode.

I'd forgotten about that until Jlannoo pointed that out.

-Ian

Really, what do I know then lol never seen that.
 
Really, what do I know then lol never seen that.

yeah, Galaga was a major fixture in our old arcade... I swear, we could never find any justifiable means for getting rid of it. so, I've seen that particular screen a lot over the years lol

I remember my mom cleaning the leafs and FIXING the coin mechs on it.
 
Video of the bootup:



Since cocktail isn't flipping and the splash is right side up, I think it is a problem with the VRAM Addresser, 00xx, like MajorHavoc said.
 
Pin 12 of the 74ls259 at 5K on the video board generates the FLIP signal. Check to see if ti toggles in a two player game in cocktail mode. If not, then try replacing 5K. You also want to check trace continuity. The FLIP signal feeds several other chips on the board -- pin 37 of the 00xx customer at at 1L, pin 13 of 6N, pin 2 of 6B, pin 2 of 4B. If it were a problem with the custom, only parts of the screen would be flipped. Same goes for any of the other chips driven by the signal. So, if there is a bad trace, it's going to be at a place that is common to all the chips using the FLIP signal.
 
I'm having the exact same issue. @mgkastra did you ever fix the issue? is there a way to set it to upright only, bodge wire an input to high all the time?

I think it's set to on when high so cutting the trace would be the opposite, which I wouldn't recommend. If you are looking for a solution like this, I would suggest using a high score kit from HSS to over right the dip settings :)

Not sure if that would resolve the issue 100% but I am semi sure as a shortcut.
 
hmm maybe lifting pin 12 on the 74ls259 ? I don't have a logic probe or scope so not sure what its doing. Yeah I don't want to cut traces. Does the HSS force vertical? I'm not sure there is a dip switch for that. The game boots up into vertical then for some reason flips :/
 
hmm maybe lifting pin 12 on the 74ls259 ? I don't have a logic probe or scope so not sure what its doing. Yeah I don't want to cut traces. Does the HSS force vertical? I'm not sure there is a dip switch for that. The game boots up into vertical then for some reason flips :/

It does:

1658641530795.png
 
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