I hate to part with my 5150, But it sits and never gets used at all
Its a stock 256k 5150
With a Sysdyne RGB, Amber, Green Monitor
Has a 20MB HardCard installed
and a Network Card.
DOS 2.11 Installed on it, Comes with mTCP installed so you can get
online with it
Has all original boxes for the system, keyboard and monitor
The Machine itself is in mint condition
$300 dollars or best offer
Thanks
Steve
> ------------------------------
>
> Message: 7
> Date: Sat, 16 Mar 2013 16:08:37 -0400
> From: Paul Birkel <pbirkel at gmail.com>
> To: "General Discussion: On-Topic Posts Only" <cctech at classiccmp.org>
> Subject: Magic Smoke: 15uf/20v bypass (tantalum?) capacitor
> Message-ID:
> <CAJj77ru8UqBprno+xXahX09J-ZZbU9DbCH7J3onv6h0HwWPz=w at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> I'm slowly bringing some olde DEC PDP-11 boards back online. In this case
> a pair of Unibus Plessey PM-1116 B core memories. Fortunately I have
> really nice documentation for them.
>
> Their inhibit drivers are driven from the -15v rail and individually
> bypassed at that point by 15uF 20v +-20% axial capacitors. The
> specification is for Sprague 150D156X002082 parts. One board uses these,
> or a very close facsimile, *electrolytics*. No smoke on power-up.
>
> The other board has KEMET axial capacitors that are bullet-shaped and solid
> plastic. I've never seen anything like them before. Has anyone else?
> Searching through parts sheets @Mouser it looks like this is a
> *tantalum *capacitor
> (but apparently a discontinued line). One of these smoked mightily on
> power-up, splitting across the middle. (Fortunately this seems like a
> non-fatal failure as regards the remainder of the circuitry.)
>
> I'm unsure whether there's any good reason to replace it with a small
> electrolytic as used on the first board (and, perhaps, all of the others
> like it on the board), or whether I should replace *just* it with another
> KEMET capacitor instead?
>
> Since no other KEMET capacitors failed (there are 17 others) I'm thinking
> that I should replace *just *it, and with a comparable modern KEMET
> tantalum capacitor; *e.g*., the T110B156M020AT
>
>
>
Tantalum caps are notorious for failing catastrophically on equipment that
is left unused for a couple years. If the power supply has lots of current
capacity, then you get the symptom you experienced. I'd change to
aluminum electrolytics, then you don't have to worry about a repeat
performance in a decade.
If you let the board sit for a few years and then power it on, you will
likely have another failure.
Jon
Photos from the MARCH club exhibit at the Trenton Computer Festival, March
16th.
http://vintagecomputer.net/browse_thread.cfm?id=509
Includes:
an original Mark 8
Altair 8800
Altair 680
IMSAI 8080
Heathkit H8
KIM-1
PDP 8e Educomputer
and more
Scored afree Amiga 1000 today sans monitor, keyboard and mouse.
Happily, it's equipped with an apparently very rare "Rejuvenator"
expansion (http://amiga.resource.cx/exp/rejuvenator), which looks pretty
cool, if it still works (it has some minor battery corrosion that I've
cleaned up...) so I'm excited to play around with this system :). I
have a compatible RGB monitor, but no keyboard or mouse. Anyone have a
set going spare?
Thanks as always,
Josh
I'm running SimH V3.9 on a PC under Windows 7 using the binaries from
the primary SimH website.
I'm running the OS8 distribution on floppy that is packaged on the Simh
site.
I attached an 'empty' RK disk drive file as RK0, and tried to run RKLFMT
on it to "format" the drive.
The RKLFMT program asks its questions (which drives to format), then
says "ARE YOU SURE?" and expects a Y or N. If N is typed, the questions
about which drives to format are repeated. If Y is typed, the
formatting process begins.
On real PDP8/e hardware, it all does what it is supposed to...the drive
does a bunch of writes, then goes back and reads the sectors to verify
that they were written correctly, then prints out a message indicating
that the format passes are complete, and then starts over with the
"which disks to format" question, at which point you can type ^C to
exit.
However, in SimH, the program starts up and asks which drives to format,
and I say "Y" to drive 0, and "N" to the other 7 drives, then the "ARE
YOU SURE?" prompt comes up, and I type "Y", and the Y echoes back, and
then it just sits there.
On real hardware, it takes about 80 seconds to format a drive. I waited
MUCH longer than this to see if the simulated RKLFMT would eventually
come back indicating that it had completed. It didn't.
I used ^E to interrupt the execution, and stepped through a few
instructions, and it appears to be hung in a loop waiting for the disk
drive to do something. I checked to see if the disk file holding the
emulated RK05 drive had changed in size, and it was still at 0 bytes.
The RKLFMT program uses the RK8E disk controller's "WRITE ALL" and "READ
ALL" functions to format and verify the drive. These RK8E commands
ignore header information on the sectors, and just writes/reads the
data, as opposed to the normal READ and WRITE commands that pay
attention to the sector header information.
I am wondering if perhaps the SimH emulation of the RK8E is flawed in
some way such that the READ ALL and WRITE ALL commands don't work
properly, causing RKLFMT to fail.
I can get the emulated RK05 to work by simply issuing a "ZERO RKA0:"
command to OS8, which writes the directory information on the disk,
making it accessible to OS8.
Has anyone run into this before? It isn't a big deal in terms of
usability of emulated RK05s in the PDP 8 SimH implementation, but I'm
wondering if it might be a technical detail in the emulation of the
RK8E that isn't quite correct.
I'd be interesting in hearing anything that folks may have run into or
heard about this.
Thanks,
Rick Bensene
----- Original Message -----
> On 3/15/2013 10:38 PM, Tom Sparks wrote:
>> I am looking for computer Art posters for my room
>> the art style I am look for date around 1970 to 1985
>>
>> Artist: Melvin Prueitt, David Em
>> Movies: Tron
>> Companies: Triple-I (Information International Inc.), Mathematical
> Applications Group, Inc.
>> Constructive solid geometry, ray tracing
> Check with David Freeman @ www.thecomputermuseum.net.
that website is dead :(
>? His original computer
> store / company / reseller (before all this "channel" crap was really
> invented) had dealings I think with Em back in the day and may have leads on
> where he is or where you can get something like you want.? I don't know
> about Melvin Prueitt, and I think they dealt with Em before Tron was out.? But I
> would ask him.
while browsing around I found www.dam.org (Digital Art Museum)
they may be able to help me
>
> thanks
> Jim
>
> kool
tom
Does someone knows a PCI PROTOTYPE CARD
possibly based on the AMCC S5920 chip ??
Or does someone ever build something comparable ?
( I know about the "dragon" board, but doesn't like it is Fpga based ;-) )
I'm slowly bringing some olde DEC PDP-11 boards back online. In this case
a pair of Unibus Plessey PM-1116 B core memories. Fortunately I have
really nice documentation for them.
Their inhibit drivers are driven from the -15v rail and individually
bypassed at that point by 15uF 20v +-20% axial capacitors. The
specification is for Sprague 150D156X002082 parts. One board uses these,
or a very close facsimile, *electrolytics*. No smoke on power-up.
The other board has KEMET axial capacitors that are bullet-shaped and solid
plastic. I've never seen anything like them before. Has anyone else?
Searching through parts sheets @Mouser it looks like this is a
*tantalum *capacitor
(but apparently a discontinued line). One of these smoked mightily on
power-up, splitting across the middle. (Fortunately this seems like a
non-fatal failure as regards the remainder of the circuitry.)
I'm unsure whether there's any good reason to replace it with a small
electrolytic as used on the first board (and, perhaps, all of the others
like it on the board), or whether I should replace *just* it with another
KEMET capacitor instead?
Since no other KEMET capacitors failed (there are 17 others) I'm thinking
that I should replace *just *it, and with a comparable modern KEMET
tantalum capacitor; *e.g*., the T110B156M020AT
Does anyone have any experience with this part, repairing boards where this
part has failed, or other words-of-wisdom to offer?
Thanks,
paul
Do any special precautions need to be taken with storing vacuum
tubes? Are these something that can simply be tossed in the attic
and forgotten about until needed? I recently got a fair number, and
expect to get more at some point in the future.
A lot of the ones I got are simply dumped in an old metal tool box.
Zane
--
| Zane H. Healy | UNIX Systems Administrator |
| healyzh at aracnet.com | OpenVMS Enthusiast |
| | Photographer |
+----------------------------------+----------------------------+
| My flickr Photostream |
| http://www.flickr.com/photos/33848088 at N03/ |
| My Photography Website |
| http://www.zanesphotography.com |
