Recent content by JeffC

I did quite a bit more testing this afternoon, the machine behaves identically with the replacement IIsi EGRET, so I think I can safely rule out a failed EGRET. I've found the machine will occasionally enter a different startup state if it has been left powered off for a while (at least 15-20...

Thanks for the suggestion, I had forgotten the EGRET is shared by other machines. I swapped the EGRET from a known-good IIsi a few minutes ago, powered on the Classic II, and still only got a black screen. Unfortunately I don't have time to test any further at the moment, later today I will take...

I am trying to troubleshoot a Classic II early four-ROM logic board. I picked the machine up 5 years ago, at that time it would only display a checkerboard screen. It had leaking caps on the logic board, so I replaced all the caps and repaired a couple corroded/broken traces. I also recapped the...

I had to scroll back and count the days since you said, and I quote, "I already hit my budget for now just getting this machine and getting it to where it is." 13 days - that escalated quickly. 🤣

You could run it without the video board and see if it still freezes, that would narrow it down to the CPU board or video board. I built a USB -> serial cable that I used to run my machine without the video board, using my Windows PC as a terminal.

Yeah the PSUs in these machines are complex. My other SGI is an Indigo2 Impact, and their PSUs are known to be quite problematic. The I2 PSUs are failure-prone, and from what I have read online, essentially unrepairable. Or more accurately, no one has put the necessary time and effort into...

I think this is solved. I ran two test leads out of the PSU, one connected to the 12V rail, and one to GND, so I could measure actual voltage at the PSU. Sure enough the PSU was generating a good 12.3V, but I was still only getting 2.2V measured at a drive connector on the backplane. I took a...

I have tried with two known-good PSUs, and the symptoms are the same with either. Both PSUs also output 12V fine when bench-tested outside of the Indigo. While I can't 100% rule out a PSU issue, I would be very surprised if both PSUs failed in a way that cause the same symptoms.

Hi all, I am troubleshooting an IP20 Indigo (R4400/Elan) that was working until a couple months ago. Current symptoms on power-on are: Orange LED No startup chime No drive activity I do get video output, and after startup I receive a “no keyboard connected” message despite a known-good...

The difference is just the "package" type. PGA and PLCC are the two 68882 package types I have seen, though there may be others. I believe the chip in your photo is a PLCC package and not QFP. The legs on a PLCC package extend out the side and curl back underneath the chip, pins on a QFP package...

You can use a 68882 in place of a 68881, for instance in a Mac II, as long as both chips are the same package (PGA).

Thanks, that's all I'm looking for 1,280 x 1,024, 17" ideally. I'll check with my local Seattle retro computer FB group and see if anyone has one laying around.

Thanks for the info, those look readily available on eBay for semi-reasonable prices.

Thanks for the info. Yes that's the cable I was looking at. I think my best bet is to try to find a monitor that can do SOG, I know some of the NEC multisync flat panel displays can. I don't know how much luck I will have tracking one down though. That adapter you mention looks like a good...

Wow that's a great blog post, I just gave it a quick skim, I'm looking forward to sitting down and reading through it. You weren't kidding about "just restored", the post is only two days old. I'll look into recapping the PSU, looking at the link in your blog post it doesn't look terribly...