[rescue] SPARC10 died today

[John Hudak]

If one is dependent on machines of this vintage, then certain preventative
maintenance areas should be addressed before the machine goes belly up.

First is that the power supply needs to be rebuilt.  Of course the filter
caps are the easy/well known things to replace.  Everyone seems to
anecdotally know that without understanding the designs of the
powersupplies.

Switch Mode power supplies (SMPS) should have the caps in the switching
circuit replaced as well before they develop a low ESR which can take out
most of the semiconductors in the switcher.
Incoming transient suppression devices (e.g. MOVs) should be replaced.

Safety circuits (OVP, OCP) within the PS should be evaluated and caps and
older carbon resistors should be replaced.
The PS feeds all the chips on the MB, and I/O devices and if the power
supply suffers an OV, it feeds that directly to the semiconductors which
can destroy them.

If there are well known failure modes of the PS, components associated with
the failure modes should be replaced.
It is generally a good idea to install components that have a higher
working voltage or wattage rating than that of the original. Heat build up
will not stress oversized components as much as the original speced
components.

Consider installing a constant voltage transformer between the power source
and the computer.  It will help reduce the effects of transients and
harmonic 'crap' on the incoming line

If the PS is loaded to within 80-90% of its capacity, one may want to
consider adding some form of forced cooling (.e.g. fan) to remove heat as
heat is the main culprit to breakdown of both passive and active components.


Keeping an old PS as a standby is illogical as a means of keeping the
machine running  because old parts are old parts and a old PS can fail and
take out downstream devices. I've seen cases where NOS PS that had been
sitting on a shelf forever installed in machines, only to have them fail
shortly after being put into service.

Likewise, turning the machines on every 3 months will keep the capacitors
from deforming and losing their capacitance but, again, it won't help the
other failure modes...old parts are old parts.

Depending on the design approach of the CPU board(s), some may employ bulk
electrolytic capacitors in the area of the power supply connectors.  Those
should be replaced.

good luck
J