🚀 go-pugleaf

In my quest to upgrade a Sun 2/50 into a 3/75, I had run
into a video problem which resulted in a "Timeout Bus Error"
when running the video diagnostics.

Thanks to some help from people on the net, I was able to
track the problem down to the power supply.  The Sun 2/50
power supply does not provide -5V to the VME bus connectors.

What is confusing to me is the following.  The Sun 3/75
Hardware Installation Manual lists the output ratings of
its power supply:

	Output 1     +5 VDC   22 amps
	Output 2    +12 VDC   1.5 amps
	Output 3    -12 VDC   0.5 amps

It doesn't mention -5V.  But then in the Power Consumption,
it shows that the CPU uses 0.8A @ -5V.  What component
provides the -5V supply?  Is there a separate inverter?

I'll probably just replace the PS with one that supplies
all the voltages.  I just wanted to post this as information
for anyone potentially doing a similar upgrade and also to
satisfy my curiosity.

-Carl (mueller@cs.unc.edu)