I'm trying to repair an AES for a customer but I'm stuck now and need some guidance. When I got it in my hands it only showed a green screen (PaletteRAM error) so I checked continuity from the palette ram chips and all was good. Replaced the chips with brand new ones and then got a pink screen (Bios selfcheck error) instead. I have checked continuity from the BIOS and all is good there to. Desoldered the BIOS and installed a socket and programmed a UNIBIOS, still pink screen. All traces from BIOS is good even after socket install. Also when I power it on, some parts of the image is black for a few seconds before drawing up the color (Think the Matrix ) With a game inserted its only garbage on the screen. The board itself looks clean and the traces I have not checked with multimeter looks good - visually, holding the board up to a light. Where do I continue now? Board revision is NEO-AES3-3 if it matters.
Red indicates work ram in bad or lacks connection. They are sony chips, the traces are very thin and prone to corrosion. If you put a cart in, turn on do you hear sound? If you do, then check the av connector for broken solder.
Thanks! I could widen my search using your tips and found out that the wrong power supply also could cause this problems, i.e pink screen and garbled screen. Switching out the 5v supply I got with the machine to a 9v did the trick For some reason the case have apparently been changed on this NEO GEO so the stickers indicated to use a 5v supply, but the mobo is a 9v one. Tricky one if you'r not familiar with these systems. Again, thanks!
