[rescue] Sun 3U Expansion Memory Questions

[systems_glitch]

No OpenBoot on a 4300 CPU board! Just the old style Sun ROM monitor. My
SPARCserver 670MP is down with a bad power supply, IIRC that has OpenBoot
but it's probably a ways off from working. The SPARCserver 330 in which the
4300 CPU board is installed is fully functional though (running SunOS
4.1.4) so I can at least test using the diags/ROM monitor.

I do have good Hakko hot air rework tools for surface mount repair, related
to my day-job. Pulling chips might be the easiest thing, considering I'd
probably have to double-stack two 3U VME extenders, and that might add its
own issues.

The other question is, is it worth the time/effort to repair? The board is
1/4 populated (8 MB), it'd probably be cheaper to find a Sun 3U board
rather than finding enough good DRAMs to populate the rest.

Thanks,
Jonathan

On Thu, Jul 18, 2019 at 5:49 PM Patrick Finnegan <pat at vax11.net> wrote:

> On Thu, Jul 18, 2019 at 3:57 PM systems_glitch <systems.glitch at gmail.com>
> wrote:
>
> > Yep, you called it, it's the old Clearpoint logo. Anyone have information
> > on this board? Joe Zatarski suggested I map it out with the logic
> analyzer
> > as he did for his VAX RAM board, but I'd rather not :P
> >
> >
> I'd hook a scope up to the chips, and see if you can find any ones that
> have the output "stuck" on or off.
>
> My usual method works better with socketed chips - start pulling some and
> see how they map out based on the new parity errors you get.  You could
> probaly do this -- cut the DO pin from the chip, see how it maps, and then
> solder it back together -- unless you have good tools, I wouldn't try
> unsoldering the chip intact.
>
> Assuming you can get to an Open Boot prompt, I'd make some Forth code
> read/write patters to the ram, and try to find the error.
>
> Anything you do is probably going to be time consuming, unless you can find
> better documentation on the board.
>
> Pat
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