First Post...newbie with space invaders issues

johnnyhotrocks

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Hi All,
I bought a midway space invaders game about a month ago, and I have been having a couple problems...
First let me say that I am totally new to this and electronics and I don't get along very well, so please speak (or type) slowly.

The first issue is the monitor...it fades during play after about 15 minutes (sometimes it fades back in, sometimes it doesn't...but it does play blind)
I am thinking chassis cap kit based on what I have been reading, but I am not sure what kind of monitor it is ...it says Amperex M50-102W

The next issue was my fault (I think)...I was checking the light bulbs behind where the marquee would be because they are all not working....somehow I caused a spark in the bulb socket and the sound immediately and totally stopped working. I know that the sounds in the game usually don't all fail at once, so maybe a power supply problem? Could the speaker be fried? Sounds were working fine until I caused the spark (dumbass...I know)

Thanks in advance for the help

John
 
For the screen blacking out and fading... look on the front of the chassis under the monitor. The potentiometer furthers on the left. Flick that when the screen goes black. It needs to be either cleaned or replaced. I have the exact same issue on mine, I'm just too lazy to pull the thing back out and clean it.
 
You guys ROCK!! It was the fuse...replaced it and now the sound works fine.
Now, I am just waiting for the screen to fade again so I can try fiddling with the pot on the left....of course, not it doesn't want to fade...after about two hours of run time....guess I have to go play it again!

As for the monitor, maybe one of you experts can identify it by a couple of crappy cell phone pics?

thanks
John
 

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Thinking about it... my pot that's causing it is the one on the far left... but the second from the left could cause it as well. So... just check both. It's a little bit of a pain sometimes, so next time you have the chassis out (rebuild or whatever) just get some contact cleaner down in those pots and that should keep them okay for a while.
 
I actually messed around with the second pot (brightness) and now my machine has stopped fading, so maybe that was the issue.
I will clean it when I replace the caps...I am planning to do it because the screen is "stretched" on the left side....or maybe it is "compressed" on the right side...anyway, adjusting the vertical pot didn't help so I figured i'd try the caps.

thanks
John
 
I actually messed around with the second pot (brightness) and now my machine has stopped fading, so maybe that was the issue.
I will clean it when I replace the caps...I am planning to do it because the screen is "stretched" on the left side....or maybe it is "compressed" on the right side...anyway, adjusting the vertical pot didn't help so I figured i'd try the caps.

thanks
John

The Wells-Gardner has linearity pots to adjust that stretching/compression. They are kinda hard to reach.....

Edward
 
Just a thought - if the screen is stretched halfway, like it looks good for half the screen THEN its stretched from that point forward, thats usually a cap thats bad causing that. Linearity adjustment may fix it some, but I'll bet not perfectly. Messing with the linearity pot only means having to correct it later when the cap gets replaced. (speaking from experience)

Now if the screen is stretched uniformly and/or only slightly un-linear, then adjust away :)

You could always try it anyway, but i'd recommend using a felt tip marker or something to mark its position so you can put it back if it doesn't work.
 
Looks like it is stretched across the screen...really noticeable when you look at the "bases"
 

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