Space Invaders question

TrevEB

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Midway's Space Invaders

This is on the same machine that has monitor woes.
After cleaning the control panel and installing new metal art plate, I fired up the game and found that I had reversed the setup for player 1-2 and the movement left-right was flaky.
So I flipped the control panel over while the machine was on and got to work setting the buttons correctly and adjusting the leafs.

Then the screen flipped out.

Displaying various invaders, letters a-z across the top and other various graphic nasties. Rows of straight lines left to right.

I powered off and on to no avail.
Instead of the screen slowly coming up showing the game in attract mode, the screen now comes up bright, then goes into messed up graphics
Can't start a game. Pressing buttons changes graphics and sometime beeps sounds.

I cannot find anything about a special button combination that would bring up a test mode, if that is what this is.

Did I just witness my ram failing and it was just coincidence that it happened at this moment?

I happen to have a new multichip, so I stuck that in but immediately got beeping error sounds. Of course, the chip didn't come with a manual so I found out later what those beeps might mean. Bad ram.

Next Visit, test voltage, maybe install new ram.
This machine does not have any sort of upgrade kit installed.
 
As others have recommended, id always suspect the rom and cpu sockets, and id also reseat your daughterboard a couple times.

Next check voltages and look for cold solder points on the power supply.

It could be a bad ram but considering it seemed to happen when you flipped the control panel makes me think bad connections.
 
I did try completely disconnecting the control board and firing up. No difference.
I'm also wondering if the 100 degree day had a bad effect on it.
 
The board can't be run without both boards in place, as the daughterboard provides the reset line to the main board. I just meant to reseat it a couple times to help clean up the giant connector between the two. That connector can cause the board to have all sorts of wierd issues, including detecting ram as bad when its not.

Fire it up without any roms and see if you get the bars going across the screen?

Also - another possibility could be that maybe your control panel wiring got caught on the coin door and bent the slam switch - if so the reset line won't work. Check that too, make sure the contacts are not touching each other.
 
Minor question: where did you find the new metal art plate?

Midway's Space Invaders

This is on the same machine that has monitor woes.
After cleaning the control panel and installing new metal art plate, I fired up the game and found that I had reversed the setup for player 1-2 and the movement left-right was flaky.
So I flipped the control panel over while the machine was on and got to work setting the buttons correctly and adjusting the leafs.

Then the screen flipped out.

Displaying various invaders, letters a-z across the top and other various graphic nasties. Rows of straight lines left to right.

I powered off and on to no avail.
Instead of the screen slowly coming up showing the game in attract mode, the screen now comes up bright, then goes into messed up graphics
Can't start a game. Pressing buttons changes graphics and sometime beeps sounds.

I cannot find anything about a special button combination that would bring up a test mode, if that is what this is.

Did I just witness my ram failing and it was just coincidence that it happened at this moment?

I happen to have a new multichip, so I stuck that in but immediately got beeping error sounds. Of course, the chip didn't come with a manual so I found out later what those beeps might mean. Bad ram.

Next Visit, test voltage, maybe install new ram.
This machine does not have any sort of upgrade kit installed.
 
TrevEB - let's start here....remove the roms, and see if you get a screen with bars going across it. If not, then its easier to troubleshoot from there. If you do, then you most likely need new roms and/or rom and possibly a CPU socket.
 
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