Galaxian Board Problem

FlavaDave

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I finally got around to working on Galaxian yesterday for the first time. When the screen comes up, you can see the stars moving in the background and it has random sprites moving/circling around the screen kind of like in a figure eight pattern. It will not allow me to go into test mode, and it has a constant drone in the sound. Any help would be appreciated! I have cleaned all the chip legs the best I could on the inside and outside but still the same outcome. I noticed that chip at 3C looks like it has been replaced before, and also at 6D...
 
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After closer inspection, those two chips look like they have some cold solder joints. I'm not going down without a fight! UPDATE: I reflowed those two chips, but still the same thing:(
 
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Poor solder on Galaxian

I have 3 of these Midway Galaxian boards, and all 3 suffer from poor soldering in various degrees. One in particular used to suffer badly from intermittent faults when you pressed down on the PCB in various places. I traced it to numerous chips with bad soldering. An easy way I found was to check the +5v and the GND pins on the TTL logic chips with a logic probe. If you get pulsing instead of a steady 1 or 0, then it's a safe bet that the chip is suffering from a poor connection. In the end, I de-soldered them, cleaned the board and re-soldered them. All up, about 10 chips needed doing. The board is rock-solid now.

Hope the info helps.

Cheers,
 
Every galaxian board I have repaired has needed new sockets. I think spaeth sells a single-rom rom board for these. Definitly a lot easier and more reliable that replacing all the sockets on the original rom board.
 
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I suspected the sockets since some of the chip legs had alot of gunk on them. Is there a way to clean out the sockets, or is it a lost cause?
 
Lost cause, those sockets were junk the day they were made. Get some good dual wipe sockets to replace them with.
 
Bingo... Replace all the ROM sockets, the socket for the ROM board to plug into, and then replace the CPU socket. BE CAREFUL that you don't pull any plated thru holes out or lift any traces. The traces on this board aren't the strongest.

RJ
 
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