Space Invaders Working Now Not Working

troxel

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Donor 7 years: 2015-2021
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I have a SI Midway upright that I have been working on. Replaced the bad rams, fixed the control and sound problem (thanks for the help on those) and thought everything was working. Played for about 10 minutes and was watching the intro screen when it went to the 16 bars. Turned off game and now I get a sound that keeps repeating along with a blank white screen.

When working on the game, I cleaned the daughter card connector, cleaned and reseated all socketed chips, and +5 is at 5.3 Vdc. Any thoughts on what to do or check next?

Thanks,
Theron
 
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Last time i saw a blank white screen was when i was doing the single rom mod but it wasnt right yet. Did you put new rom sockets in?
 
I put in a new socket for the 8080A, but not ROMS. I didn't have any on hand. I might have to try the single rom mod. Any other thoughts or are you thinking bad sockets on the ROMs?

Theron
 
I did the single 2764 rom modification, and still getting the same problem. I get a repeated sound with a white screen. I didn't replace the 8080A. Would a bad 8080A cause a white screen?

Any other ideas to check?

Thanks again,
Theron
 
Its possible, although repeated sound kinda sounds like some other problem is at play...processor may be resetting.

You did check all the voltages including the reset voltage, right?
 
The reset voltage was fine last time I checked, but I will double check this evening and see what some of the voltages are reading. Any other thoughts on what could be wrong besides the reset?

Theron
 
This may not help, but the last time i saw a white screen was when i had a shrted TAN cap near my RAM chips
 
The reset voltage was fine last time I checked, but I will double check this evening and see what some of the voltages are reading. Any other thoughts on what could be wrong besides the reset?

Theron

Reset line prob not it but I'd recheck anyway - if the processor isn't working it'll have a patterned/scrambled screen. White screen would mean a constant signal to video, like something got shorted or a line is stuck high somewhere.

I saw a post about someone having a similar problem with an 8080 game last night but I can't remember what it was or if there was a fix on it. Try searching boot hill or gun fight white screen and see what you come up with. They all use the same main board.
 
Had a chance to double check the voltages. I am missing the +12 volts. It was measuring 0.5V on the power supply and 0.35V on the edge connector. Is there certain parts to look at on the +12, or is it time to order Bob's rebuild kit?

Theron
 
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