Re: DECstation 2100: power trouble?

[Mouse <mouse%Rodents-Montreal.ORG@localhost>]

>> I've got a [KN01].
> Yes, KN01 is either a DECstation 2100 or a DECstation 3100.  The
> difference is in the CPU clock rate only, 12MHz vs 16.67MHz.

I do see a 25MHz crystal only an inch or two from the CPU, so I suspect
it's 12.5MHz and thus really is the 2100 the case makes it out to be.

>> I tried turning it on.  [...lights acting odd...]
> Lights at EF would be memory.  [...]

Where are these documented?  I guess I haven't found the right document
yet.  Is this the PDF you mention below?  I'll have to look for a copy.

> These systems are quite sturdy, though as anything made by humans can
> fail from time to time.

Oh, sure.

> NB you do need to have all the required peripherals (keyboard, mouse,
> network) connected or the system won't boot to the console monitor
> prompt.

See below.

>> I opened it up and there is nothing obviously wrong [...]
>> But the power supply connector [...]
> The pinout is given in "VAXstation 3100 Model 76 Maintenance Guide";
> search for vs31mmg2.pdf if you don't have a copy.  Mind the isolated
> -9V circuit.

-9V?  Iiiiinteresting.  I'll have to find a work machine and see if I
can scare up a copy of that PDF.

> The same PSU is used with the SZ12/BA42A expansion box, where a load
> resistor at 2Ohm is wired between +5V and GND, so I'd be wary running
> the PSU with no load.

2 ohms on 5V is 2.5A for 12.5 watts, hm, yeah.

But see below.

>> [...], for my purposes I'd prefer a working FrankenPMIN to a dead
>> original-equipment PMIN.
> I reckon you might get away without the -9V line.  I'm not sure if it
> was actually used for anything with the KN01.

Well, I've done a little more with it.

I looked it over and saw nothing obviously wrong, so I connected power
supply and battery pack back up on the bench.  I turned it on
and...still nothing.

But then I noticed a jumper between two of the pins on the miniDIN-7
marked with a mouse icon.  I removed that (thinking it may be making
the ROM code think it's got a mouse and therefore a monitor) and, while
it took some seconds from powerup, I got a KN01 V7.0 banner on the
printer port serial line (nothing connected but power and serial).  It
got to test 3 ("7..6..5..4..3..") and then I got a ?? getting erased
and redrawn on the next line.  I eventually found that ^C stopped it,
printing "exit(-1)" and giving me another banner and a language prompt.

But I now think I may know why I didn't have it out where I could run
it: after netbooting it a couple of times (took me forever to find the
command - btw, is there documentation on the console command language?
maybe in more vs31mmg2.pdf?) and in the process discovering I had a
NetBSD/pmax netboot setup set up, it then seems to have decided to stop
working:

KN01 V7.0 
08-00-2b-14-8c-7e
0x00000000
>> boot -f tftp()
1845632+65024+374812-47c xfr addr: 0x80030000

Excptn:    <vtr=NRML>
Excptn pc: 0x801c9670
Creg:      0x1000001c<CE=1,EXC=DBE>
Sreg:      0x20080000<CU1,CM,IPL=8>
Sp:        0x8002ffb0
exit(-1)

KN01 V7.0 
08-00-2b-14-8c-7e
0x00000000
>> 

So I'm not sure where to go from here.  The power supply fans seem to
be moving a reasonable amount of air, but on the possibility that it
was something thermal, I opened it up and removed the disk mounting
plate, so the PCB is in the open.  For two consecutive powerups it
didn't even banner.  Then it bannered, but, on booting, gave the above
"Excptn".

I am feeling I may have dead hardware on my hands. :-(

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