H7874 power supply

Rob Jarratt robert.jarratt at ntlworld.com
Sun Mar 29 16:04:47 CDT 2020

I have some notes I made about trying a PC PSU, I don't think it really worked, there are signals to indicate power OK and perhaps others. But perhaps a more concerted effort might yield something that could work.



> -----Original Message-----
> From: cctech <cctech-bounces at classiccmp.org> On Behalf Of Robert
> Armstrong via cctech
> Sent: 29 March 2020 19:15
> To: 'Maciej W. Rozycki' <macro at linux-mips.org>; 'General Discussion: On-
> Topic Posts' <cctech at classiccmp.org>
> Cc: rob at jarratt.me.uk
> Subject: RE: H7874 power supply
> >Maciej W. Rozycki <macro at linux-mips.org> wrote:
> >numerous Chemi-Con SXF parts scattered across all boards, some leaking
>   Yeah, mine is full of "Nippon Chemi-Con" electrolytic too.
>   What about just gutting the PS chassis and sticking in an ATX power supply?  I
> don't know how the maximum current per output breaks down, but as I
> understand it the H7874 is only a 600W supply.  That's not a problem for an
> ATX supply, and it would have all the required output voltages.  You'd have to
> run the cabinet fans at a fixed speed and you'd lose the power control bus
> feature, but that's not a show stopper.
>   Actually my unit is in an R400x chassis full of RF drives, so I believe I only need
> +12 and +5.  I don't think the 3.3v and -12 are used in that case.  I wonder how
> much current I really need for the drives?  I should look that up and I might be
> able to find a surplus dual output supply that would do the job.
> Thanks again,
> Bob

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