Octane Short/PSU Problem

[bnoji]

I acquired a base model Octane (CMNB015ANF175) this weekend along with a second PSU. The previous owner said it was in use, froze while running and wouldn't boot again after that. He bought a new PSU and it still didn't work.

I plugged it in and both the chassis fan and PSU fan spin up for a second until the relay clicks and it shuts off and sits idle with a slight buzz. It sounds (and smells) like a short somewhere. I pulled the power supply out but I can't tell if that smell was from the chassis or the PSU. I opened the PSU and there's nothing obviously smoked and both fuses were fine.

The other PSU doesn't do anything so I'm assuming that's the bad one.

Are there any points on the boards where shorts are "common"? I'd hate to buy a third power supply only to find out it's a short on one of the boards instead. It seems like this PSU is working but hits some over current protection or short protection and it shuts down.

Edit: The one that doesn't do anything is a Lucent and the other is a different manufacturer.

 

[stormy]

Sorry nobody is replying to you, there is not much experience in fixing Octane PSU's. This thread might be helpful for you: https://forums.irixnet.org/thread-4349.html

 

[Richard42]

I have repaired a couple of Octane PSUs - one was a Lucent model with a bad AC/DC converter. IIRC with that one it wouldn't do anything when the power button was pressed. There is a lot of good info for fixing this problem in this thread:
https://forums.sgi.sh/index.php?threads/octane-psu-repair-click-of-dead.666/
The second one was a Cherokee PSU which shorted internally and blew the fuse because the handle broke off during shipping and the internal screw wedged itself perfectly between two big heatsinks with opposite polarity

You can test the power supplies outside of the computer by turning them on by pulling the Inhibit line low, but they need to have loads on their outputs or they will automatically shut down within a very short time (on the order of 0.1 seconds). I don't know how much load they need to see because I've never successfully tested this way.