Do you have a spare frontplane/edge connector board? Or at least a decent way to really clean out and spruce up the old one? Worth considering in case you swap the DG and problem persists
This happened to me once. It's definitely worth trying. You can clean it with a can of IPA (alcohol).
The RM's are vertically oriented. I don't mean the PCB in the card cage, but the organization of pixels in frame buffer memory. So a single bad RAM chip will take out a vertical 'line' of pixels on the screen. A bad soldering joint in one of the address/data lines one of the image engines or RAM chips will result in a dotted vertical line on the screen. This phenomenon is better known as the Pinstripe of Death
. And it's pretty common in 'big iron' graphics, especially RM4/RM5 and first generation IR, unfortunately. It seems to be the result of thermal and/or physical stress.
A bit of context: the older generation (VGX) was all through-hole technology and it Just Works, even today. Reality Engine is SMD and those RMs can flex pretty badly so after a while the connections go bad. Just like Indigo2 IMPACT TRAM's
, now that I think about it. InfiniteReality2 RMs are a much more rigid construction and more reliable in my experience.
The DG creates the analogue signal which is by definition horizontally oriented. That's how CRTs work. I've got several DG's here that are busted in one way or another but it's usually an unstable picture (sides are not vertical, but 'wavy') or 'no picture at all'. There's some DMA memory on it and the diagnostics tell me this sometimes goes bad. But nothing ever resulted in vertical pixel stripes.
Now this is a deep dark secret, so everybody keep it quiet
It turns out that when reset, the WD33C93 defaults to a SCSI ID of 0, and it was simpler to leave it that way... -- Dave Olson, in comp.sys.sgi
Currently in commercial service:
In the museum
: almost every MIPS/IRIX system.Wanted
: GM1 board for Professional Series GT graphics (030-0076-003, 030-0076-004)