[rescue] Re: SPARCclassic restoration

[Richard]

He folks

A bit of an update.

So replaced the final 2 capacitors tonight but still not much further on.

with the HDD disconnected the PSU doesn't fire up (no fan)
with the original HDD the PSU fires up but the machine only boots as far as
testing memory then powers off.
with an alternate HDD the PSU fires up and the machine boots to the OK prompt
and I have been able to reset the idprom at . However on boot from the HDD the
machine powers off.
with a second older alternate HDD the machine wont even power up.

So some research found the very good  Switch Mode Power Supply FAQ.

https://www.repairfaq.org/sam/smpsfaq.htm#smpsmcp

Based on the above and the comments in the most common problems I suspect that
the over current sensing part of the supply has an issue....now to work out
where that is....

Cheers

Richard


On Wed, 28 Mar 2018, at 6:56 AM, Richard wrote:
> Hi Mike
>
> So to get this far I have replaced all but 2x capacitors on the low
> voltage side of the PSU. One is a 1200uF electrolytic which just isnbt
> in the available catalogues locally. Would appreciate substitution
> thoughs if anyone has experience. 2000uF? Maybe my answer is there.
>
> Interestingly if I take the HDD off of then PSU then it wonbt boot. So
> this suggest I still have a PSU issue.
>
> Have already stripped down the memory as suggested. Also tried different
> pairs of SIMM just in case.
>
> So I think I am at
> - replace final 2 capacitors
> - replace PSU
> - wash main board - it looks clean, but never know there might be
> something thatbs causing an issue
> -?????
>
> Thanks for the thoughts
>
> Cheers
>
> Richard
>
>
> Sent from my iPhone
>
> > On 27 Mar 2018, at 23:12, Mike Spooner <mike.spooner.ux at gmail.com> wrote:
> >
> > I've seen this "mystery sudden poweroff after POST" on a couple of
> > SPARCclassics a few years back. A replacement PSU fixed one of them but
> > not the other :-(.
> >
> > I suppose the obvious belt-and-braces thing to check is the RAM SIMMs -
> > must be installed in pairs, try with just a single pair of 16Mb SIMMs,
> > one each in the 1st and 4th slots counting from the SBus end of the
> > chassis, and swap-in any other 16Mb 72-pin parity SIMMs you have lying
> > around to see if that helps.
> >
> > Of course, it could still be a PSU issue... If you remove the internal
> > HDD, does it try to boot off the net after POST?
> >
> > Out of curiosity, what did you have to do to the PSU to get this far?
> >
> > -- Mike Spooner
> >
> > --------- Original Message ---------
> > From: Richard
> > To: rescue at sunhelp.org
> > Date: Tue Mar 27 12:38:38 GMT+01:00 2018
> > Subject: Re: [rescue] SPARCclassic restoration
> > Quick update
> >
> > OK so on a hunch replaced the NVRAM chip.
> >
> > On power on, Pressing STOP-D to start power on self test. Serial console
> > plugged into ttya.
> >
> > The machine now gets through post past the below error and goes through
> > to
> > ....
> > NVRAM Access Test
> > TOD Registers Test
> > Then identifies the memory in each bank
> >
> > and then powers off....!? Might have more work to do on the power supply.
> >
> > Richard
> >
> >> On Tue, 27 Mar 2018, at 9:24 PM, Richard wrote:
> >> Hi Folks
> >>
> >> Trying to bring back a SPARCclassic. Just finished rebuilding the power
> >> supply and it now powers up.
> >>
> >> However it fails to get past the following which is the first thing
> > that
> >> comes out on the serial console.
> >>
> >> ERROR: FPU Exception Did Not Block Store, addr = 00600000, exp
> > =00000000,
> >> obs = -f884010, xop = 0f884010
> >> U-NUMBER : Suspect Tsunami Module
> >>
> >> Any suggestions, thoughts or guidance on the above error greatly
> > appreciated.
> >>
> >> Regards
> >>
> >> Richard
> >> _______________________________________________
> >> rescue list - http://www.sunhelp.org/mailman/listinfo/rescue
> > _______________________________________________
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