So I have acquired a lot of Neo Geo big reds and one was a 4 slot and this on just boots up to what looks like a bunch of corrupted " F " letters. (though I doubt they are the letter "F" since my cab is setup as vertical.)
I have never seen this before and was wondering if anyone had any pointers in the right direction???
-The battery was changed at some point (this has been removed by me now)
-one of the Ram chips was replaced with a Cypress ram chip with faster than equiv speed (aka this is compatible).
-about 8 or so traces looked very damaged around one of the PCB stand offs
-everything looks very clean
- one of the custom chips as a red permanent marker line on it (repair note from a previous tech??)
- This system was pulled already wired and installed in a cab with 4 games so I assume it was used and working at some point.
- no real signs of bad solder joints or board damage
Done so far:
- removed the battery on the board.
- reflowed solder to the replaced ram chip (this had no change to the output of the video)
- removed the ram chip from the board to check for damaged traces, saw no damage.
- ran the board with out the ram chip to see if there was any change in behaviour. (no changes without the replacement ram chip)
- replaced the ram chip and neatly and correctly re soldered it to the board.
- ran a continuity test for the majority of all traces around the damaged traces on the board all traces plus more in the area tested ok for continuity
Any ideas or hints to the right direction would be super fantastic.
I am testing this without a game installed in any slot am I an idiot or is one needed to even get the machine to boot properly
Install Neo Universal Bios
Replace the ram chip with another known good ram chip i have in stock.
Reflow solder on the 3 large custom ASIC chips
Thanks so much guys and gals
Searching for: DDP DFK 1.5, Black Tiger, Magic Sword