[rescue] SPARCserver power supply

Michael Thompson michael.99.thompson at gmail.com
Sat Jan 1 07:35:20 CST 2011

> So, I may not have permanently damaged my CG3?  Phew.  BTW, is there any
> difference between 'cgthree' and 'CG3'?  I have seen both terms used and
> don't know if they apply to the same card.

One of my 3/80 systems vaporized a tantalum cap on the motherboard and
kept on working. It still works fine.

As far as I know all of the CG3/cgthree frame buffers are
architecturally the same. There are quite a few different physical
implementations for the VME bus, S-Bus, and P4.

> Replacing the capacitor looks like being difficult since it is
> surrounded by a solid steel chassis and I have no disassembly
> instructions or diagrams; my SPARCserver being a 'deskside' unit, it's
> large and quite heavy (I dropped it on my toe once - oww).  I can see
> the frazzled component through the chassis around the VME slots.

The backplane is removable, but it takes a bit of work.

> I'm wondering if the capacitor damage may have been done by the PSU's
> -5V output briefly swinging positive.  I don't trust that PSU and am
> going to replace it as soon as I can.

I think that reverse polarity from the power supply is unlikely. I
have seen lots of tantalum caps just vaporize.

Michael Thompson

More information about the rescue mailing list