SGI: Hardware

Hi Pontus,

having also refurbed the PowerOne in my Crimson (thanks to some vital info from Jan-Jaap!), I also recommend replacing the 250V EMI supression caps on the backplane and the primary module, even if they show no cracks; they're bound to develop some, and you don't want to extract the PSU again anytime soon when one of these turns to charcoal.

I'd also strongly suggest replacing all the 47µF electrolytics (probably Nichicons) strewn about the backplane. These had leaked in my PowerOne and caused it to powercycle erratically, i.e., oscillate several times a second! Do yourself a favour and replace these proactively. See attachments.

Check the secondary caps on the output modules while you're at it; on most PSUs these will give you agro, but they were (and still are) fine on my PowerOne. I guess it comes down to effective cooling.

Btw, some bonehead had actually bridged the blown fuse on my 5V module with a wire! I ended up replacing it with a proper fuseholder.

Be very careful when connecting the PSU after installation. Jan-Jaap actually blew the "littlefuse" on his primary board after connecting the terminals labelled 1 and 2 in error.

Good luck and a happy new year,

--Roland

I'd also strongly suggest replacing all the 47µF electrolytics (probably Nichicons) strewn about the backplane. These had leaked in my PowerOne and caused it to powercycle erratically, i.e., oscillate several times a second! Do yourself a favour and replace these proactively. See attachments.

Now there is an interesting tidbit. I had noticed the last time I had left the Crimson on it would occasionally lose power to the drive cage and reset everything. Looks like I'll be pulling my PSU as well to inspect this.

Hi Pentium,

yeah, that's how it started on mine: sporadic resets for no reason, then got progressively worse. In the end I noticed the power LED on the panel flickered; that's when I figured the PSU was getting a dodgy start signal from the panel, but the fault was in the PSU itself, namely the backplane after those caps leaked (though thankfully without serious damage to the PCB).

Apart from preventive maintenance, pulling and dismantling a PSU that can churn out 170A into 5V is quite an educational experience.

Good luck,

--Roland

I had a four channel logger hanging off the power rails. It marked an event every time the voltage dropped below a threshold and used that to see if some sort of trend was forming which as you mentioned it did.

If you don't hear from me again, sorry boys but no rainchecks on my stuff.

Thanks everyone that has chipped in on this thread. I have not abandoned it. Real life came crashing down on me though.. so...

But I have replaced the MOSFET and controller and the backplane is seemingly behaving on the bench now. I've decided to replace the caps on the backplane as well as the machine behaved a bit weird with respect to the front panel power button before the fuse blew. I might as well.

I will try the Crimson before that though. I hope it works a little better since I want to display it on a local computer expo in a week.

Congrats, Pontus.

Looks like the time invested in recapping did save you some headaches down the road.

Btw, still no luck on my end with a replacement CPU for my VAX 4000 (sorry for the OT).

Good luck with the expo! I'd love to hear the reactions to a working Crimson. The RE in mine is positively on its way out.

--Roland

The Expo went great!

The Crimson gave me scare when it decided to turn itself off after 30 minutes. I decided to play wild west and restarted it and it ran fine for the rest of the show, about 7 hours or so. It was great fun and I got quite a lot of interest.



I will not turn it on again until I've recapped the PSU.

There is also a video, in Swedish, with me talking about it, at 10 minutes 20 seconds in, I get to talk for about 7 minutes.

Great to see it got the attention it deserved; too bad the PSU decided to cave just then, infact the very instant the guy touches it!
The disk is in the external enclosure, right? Nice combo with the Indigo, btw. Congrats!

Check out the LG2 "Song And Dance" Graphics card on display on top of the Crimson. So neat!

That's a neat display!

Thank you

GanjaTron wrote: Great to see it got the attention it deserved; too bad the PSU decided to cave just then, infact the very instant the guy touches it!
The disk is in the external enclosure, right? Nice combo with the Indigo, btw. Congrats!

Yes, The original full height drive is saved for later