Recently I acquired a H9276-A backplane, and decided that I wanted to give it a try. I looked through the LSI Systems Service Manual Volume I (https://manx-docs.org/collections/antonio/dec/ek-lsifs-sv-005-vol1.pdf) to understand what all of the jumpers and things are for since they're not labelled as they are on my H9270 backplane.
On pages 364 and 365, it's easy to see that the screw terminals on the D side of the backplane are where the normal power connections go. And, handily enough, they're labelled 1-8, with the functions of each listed. Easy! I connected the screw terminals to the proper wires, following the guide on page 365, inserted my CPU board, and turned on the power...and immediately blew fuses on my power adapter!
When I started beeping out the pins, it seems that the H9276 that I have is actually pinned BACKWARDS from the way the service manual listed! Terminals 7 and 8 are +5, terminal 1 is +12, and terminals 2-5 are GND. I guess I learned again to always, ALWAYS, trust but verify. Hopefully I haven't broken my CPU board...
This wasn't intended to be a rant, but maybe what could be a sticky topic here that lists gotchas like these so that others don't run into the same problems. Unless there's something like this that exists already?
On pages 364 and 365, it's easy to see that the screw terminals on the D side of the backplane are where the normal power connections go. And, handily enough, they're labelled 1-8, with the functions of each listed. Easy! I connected the screw terminals to the proper wires, following the guide on page 365, inserted my CPU board, and turned on the power...and immediately blew fuses on my power adapter!
When I started beeping out the pins, it seems that the H9276 that I have is actually pinned BACKWARDS from the way the service manual listed! Terminals 7 and 8 are +5, terminal 1 is +12, and terminals 2-5 are GND. I guess I learned again to always, ALWAYS, trust but verify. Hopefully I haven't broken my CPU board...
This wasn't intended to be a rant, but maybe what could be a sticky topic here that lists gotchas like these so that others don't run into the same problems. Unless there's something like this that exists already?
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