[rescue] HP 9000 712/* power supply?

[Mike Spooner]

Re: 5.1V - it makes all the difference on a different system - the SPARCstation-10. Mind you, the cable harness for *that* is made of aluminium wire, so high-resistance.


On 6 June 2025 18:46:57 BST, Mouse via rescue <rescue at sunhelp.org> wrote:
>> I presume this is the manual you already found: =
>> http://ftp.parisc-linux.org/docs/platforms/712_technical_manual.pdf,
>
>I found it on manualslib.com, but, except for manualslib's obnoxious
>UI and the line they add to the bottom of each page, it looks the same
>(I side-by-side skimmed the first half-dozen pages).
>
>> the =
>> power supply stuff is in 7-1, also a small bit about the =
>> START_PWR_DOWN_L signal.
>
>I saw that.  I may experiment if I can't find anything more definitive.
>As long as the board is happy with nothing driving either pin, I should
>be OK.  If it doesn't work, I'll try pulling the pins to various
>voltages with 1K or so resistors....
>
>Not that that's going to happen soon.
>
>Actually, looking at table 7-1 now, I see that it says the main +5 is
>actually supposed to be +5.1V, though I am inclined to doubt the
>difference matters.
>
>Page 7-2 says that a flashing light on the front panel indicates "a
>problem with your graphics subsystem".  You've actually got a machine
>to look at; can you tell whether that LED is driven by the power
>supply, as implied by the PDF's "on the power supply" implies, or by
>the board?  If the former, there must be some more complex protocol
>than just a logic level between board and power supply....
>
>> The wire colours described match what I have in my 712/60 (the
>> motherboard is A2263-66510)
>
>That's reassuring.
>
>> pin one/white wire is closest to the SCSI connector.
>
>That matches the pin numbers silkscreened onto the board I have (there
>there are numbers 1, 5, and 10 next to those three pins, the same on
>each side).
>
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