I do, and it shows up the same way; devoid of color. On my other spi it works
fine.
Should I start with the caps? It seems the cheapest thing to do
before I order the three new dacs.
I don't even know what kind of voltage should be going on in the spi, there's just so little info..
Not going to be the caps... Also, I kinda doubt that it'll be the resistor arrays (the LAS4K's, which seem impossible to find *any* documentation on online). They were made by Kyocera-- the three little numbers at the end are the date code.
The only way you're going to get a 'greyscale' output from a RGB system is if all three of the color guns are outputting the same voltages-- almost like they're tied together.
The way it works is that each 'DAC' is fed a five bit value and it generates a proportional output voltage. That value is coming from the SIE150 chip.
Either the SIE150 is outputting the same value to each DAC (RGB), or somehow they're tied together. I'm not at all sure what the SIE150 is doing (if it's combining multiple possible pixels from different layers and outputting the mixed result, or maybe it's a big palette lookup table, etc.), but I would say to try to reflow the solder on the all the pins just to be sure that the connections are good.
Just as a sanity check-- take you multimeter, set it to ohms, and measure for resistance between the red, green, and blue output pins on the JAMMA edge connector. If any of those reads zero ohms (or some very small resistance) they could be physically shorted together somehow. (Weird, but possible.)
Post back with your findings and we'll go from there.
-Clay