Got a lc575 board for my mystic a few weeks back. I first got it and installed it without knowing you have to do the resistor mod or otherwise mod it to work with the CC. I popped it in and turned it on, it came up fine but within a few seconds of the screen coming on and displaying, the video got glitchy and stayed that way. I later did the resistor mod to run it at the native CC resolution but the video is glitchy.
I havent recapped it and it doesnt look like the caps have leaked and corroded, but i did give it a good wash in 99% isopropanol and distilled water. Changing the video color modes is also strange. at 1bit, 4 bit and 8 bit color, its very glitchy, but at high color, its nearly perfect with the 2x512k simms
I supsected the VRAMs were bad, it came with 2x 512k simms. I ended up buying a new set of 2x 256k simms and put them in. upon boot, its got vertical bars, but compared to the 512k simms, there isnt fuzzyness on the screen, just vertical bars. If I switch to high color, the video is perfect and works, any other mode and its got the vertical bars again.
I've looked around on here and found a few threads with similar issues. I know there's no schematics for the 575 board. What I did do is reflow solder on the simm slots, I also reflowed solder on the RAMDAC, neither of which made any sort of difference. I also reflowed every single leg of every single resistor pack on the back side of the board, still no difference.
I did see another thread with a missing connection to RP9 on another thread. I did a continuity test on RP9 and every single pin from 9-16 had a connection to the VRAM simms, nothing on pins 1-8.
That's as far as Ive gotten, could use some help!
I havent recapped it and it doesnt look like the caps have leaked and corroded, but i did give it a good wash in 99% isopropanol and distilled water. Changing the video color modes is also strange. at 1bit, 4 bit and 8 bit color, its very glitchy, but at high color, its nearly perfect with the 2x512k simms
I supsected the VRAMs were bad, it came with 2x 512k simms. I ended up buying a new set of 2x 256k simms and put them in. upon boot, its got vertical bars, but compared to the 512k simms, there isnt fuzzyness on the screen, just vertical bars. If I switch to high color, the video is perfect and works, any other mode and its got the vertical bars again.
I've looked around on here and found a few threads with similar issues. I know there's no schematics for the 575 board. What I did do is reflow solder on the simm slots, I also reflowed solder on the RAMDAC, neither of which made any sort of difference. I also reflowed every single leg of every single resistor pack on the back side of the board, still no difference.
I did see another thread with a missing connection to RP9 on another thread. I did a continuity test on RP9 and every single pin from 9-16 had a connection to the VRAM simms, nothing on pins 1-8.
That's as far as Ive gotten, could use some help!
