22 Sep
2015
22 Sep
'15
5:21 p.m.
Hi. The original ROM request showed up just before I started receiving
messages this morning, and I only got the tail end of the chatter. Instead
of tacking a reply on to that, I thought I'd just start a new thread and
introduce myself at the same time.
Here's what I think is 23-038e4-00 from an LA120 (with a bad print head,
and dead pin drivers as well). I couldn't find anything to compare it
against, and the adapter is new. So it might be gibberish. I did see, at
least, [A-Z] in the dump, so maybe it's good.
As for the introduction, I started life on the Apple II in fourth grade or
thereabouts, finally got a Commodore 128, then an Amiga, then jumped over
to UNIX (BSD mostly) and stuck there for years doing software. After
funding stopped being an issue, I decided to get back to more interesting
and/or simple hardware, and electronics in general. I seem to have
collected a rather complete HP86/87, under the illusion of using it for an
GPIB controller. I'm now wrestling with an apparently dead PSU on a
MicroPDP (actually, I just now gave up on it), and am slowly fixing up a
PDP-8/a. It has two CPU boards, one of which ignores the HALT
instruction. From the schematics, I think it's one faulty 74ls chip, but I
haven't tried fixing it -- the machine has been down for cleaning/painting
for many months. I just got it put back together this weekend. I also
swapped out the fans for modern (quiet) 12v fans (driven off an isolated
power supply powered by the original 120 vac fan supply)...and now hear the
transformer buzzing away. Win some, lose some. Sigh. Congrats on making
it to the end!
Cheers!
b
22 Sep
22 Sep
9:29 p.m.
Hi Brian,
WELCOME!!
What is the part number of the dead power supply you gave up on?
What other DEC items do you have?
Where are you located?
Thanks, Paul
23 Sep
23 Sep
4:54 p.m.
On Tue, Sep 22, 2015 at 9:29 PM, Paul Anderson <useddec at gmail.com> wrote:
What is the part number of the dead power supply you gave up on?
It's the H7864 (Astec aa12130) in the BA23 enclosure.
It powered up a few times, but now only the switch light comes on. If I
remember, it wouldn't power up with just the cpu board (or maybe just the
cpu + memory), but with cpu, memory, disk controller + disks, it would
power up. I was able to poke around in the 'boot menu' (enough to see that
the machine and serial port worked), and the next morning it wouldn't power
up.
I checked for cold solder joints, and replaced one of the three line filter
caps - the other two aren't the exploding type. I'm getting power out of
the filter anyway and the rectifier is OK (voltage across the two caps). I
don't know switching power supplies well enough to go poking around in
there.
What other DEC items do you have?
The MicroPDP (KDF11-BJ, 128 kw memory)
VAXstation 3100 (m48 sounds right) running OpenVMS (probably well expired
by now)
DECstation 5000/120 (+ 2x disk expansion) running Ultrix. As I recall,
this was a DNS server at BBN. I thought I saved the original bits, but I
see I was in the mucking about before I made the copy.
DECsystem 5000/200 - which I've been able to do nothing with. I should
haul it out and see if I've gotten any smarter since the last time I tried
it.
LA120 DECwriter III (cleaned and repainted, NOS ribbon and a box of paper)
LA120 DECwriter III (dead; print head is jammed, and the 'LSI printer' IC
is bad)
PDP 8a/400 - 3x m8315 (one that ignores HALT, one that doesn't work, one
that hopefully works 100%), 2x m8316 & m8317 & 8k core)
PDP 11/34a + 2x RL01's - a winter project. All I've done is clean out the
dust and whatnot. I'm pretty sure I'm missing the cable to connect the
controller to the disks. Annoyingly, one of the keypad buttons is busted
off, and previous 'repairs' (not mine!) screwed up the joint enough that I
had to make a bridge to glue it back together. The membrane button below
it now feels weird - no 'click'. I _really_ don't want to take this
apart. Did that on the 8a, and it was a nightmare.
Where are you located?
Just north of Washington DC. Anyone else?
b
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