A sick, sad Tezro.

kln_nurv

New member
Jun 2, 2020
2
0
1
About 8 months ago I picked up a lightly beaten but working Tezro for a very good price. It's a quad 1Ghz, 4Gb Flame machine and came with no accessories. I used it at least monthly without problems. Recently it was sitting idle for about 3 months and it seems to have developed power issues.
I get the equivalent of a Mac's 'quarter fan spin' and L1 says "powered off" then "power up error". The only message I can access via the L1 complains about fan 8 being at 0rpm. Serial console however complains about a bad 12v VRM. The LEDs next to the node board backplane connectors are orange.

What I've tried:
Using a 1000W ATX power supply. Same symptoms.
Unplugging fans to find the bad one. They all spin when plugged in and it only complains about 8.
Removing all unnecessary hardware. Same symptoms.
Reseating the HP-style VRM. Same symptoms.

I appreciate any help available here. My initial questions are about fan numbering and which VRM is which. Beyond that I'm not sure. One step at a time.

I am open to offers for the machine, fixed or not, but not actively looking to sell it. Ifit's not too expensive to fix I'll probably keep it around for a while and do some upgrades. I'm in Thailand and I expect shipping to US/EU would be almost as much as a good working machine.
 

Elf

Storybook
Feb 4, 2019
273
63
28
Hello and welcome!

For VRM information, see here: https://forums.sgi.sh/index.php?threads/tezro-voltage-regulators-and-rails.140/
Long story short, I do not believe there is an actual 12V VRM per se; the environmental monitoring complaining about the 12V VRM is probably referring to one of the three separate 12V rail inputs on the motherboard from the PSU.

I would suggest testing further to see whether the motherboard is actually receiving 12V and it is an environmental monitoring issue, or perhaps it is not receiving it and something is wrong with the connector or further.

I wish I could help with the fans but I have not counted them off. It is possible there is guidance inside the machine or on the fan tray? Or perhaps in a techpub (see https://irix7.com/techpubs.html / https://techpubs.jurassic.nl/ ).
 
  • Like
Reactions: kln_nurv

kln_nurv

New member
Jun 2, 2020
2
0
1
Thanks for the reply. The owner's manual doesn't say which fan is which but I have a working hypothesis to test:
The failed 12V rail (on the original PSU) is the same one that's missing on the ATX replacement. A VRM is able to tell that the pins are from the same rail vs 2 separate rails. And fan 8 is either whichever one gets power from the 'missing' rail, or the PSU fan.
This is looking good. If the problems are in 12V-land, and on the left-hand side of the machine, that's something I can work with.
I have 3 different brands of 1000W PSUs, 2 of which I might be able to get 3 rails out of. I tried an Asus 550W PSU as well, and there was no sign of life. That makes me think there's something else that is being checked, other than current output, which doesn't go through the 5 pin cable.

In your linked post you mention testing your machine without fans. Does that mean that power up should not be blocked by fans simply being missing? I assume a shorted or near-shorted fan would cause an error though.
 

Elf

Storybook
Feb 4, 2019
273
63
28
I was able to power it up with the internal fan wall removed, didn't try to remove any others, if there are others (I don't recall). I forget whether or not I had to disable environmental monitoring though (which is something you can do; env off in L1, I think, although at your own peril).

Regarding the three 12V rails, I don't think it matters that much whether or not the PSU you are using has three separate ones. In the original Delta supply, the three "rails" come from one regulator but are put through separate current monitoring, presumably for separate over-current thresholds. That is to say, as long as the PSU you are using supplies power to all the 12V pins you should be fine, although perhaps missing the over-current detection safety of the original.

A little more here: https://forums.sgi.sh/index.php?threads/ugly-tezro-power.134/
 
  • Like
Reactions: kln_nurv

About us

  • Silicon Graphics User Group (SGUG) is a community for users, developers, and admirers of Silicon Graphics (SGI) products. We aim to be a friendly hobbyist community for discussing all aspects of SGIs, including use, software development, the IRIX Operating System, and troubleshooting, as well as facilitating hardware exchange.

User Menu