A little while ago I posted about a H7864 PSU (from an rtVAX 1000) that
had failed on me with a loud pop and no apparent physical damage. I
discovered which component has failed and it is a large transistor, Q301,
but I have yet to find out why it failed.
To help, I have been working out the schematic for the area of the PSU
that failed, which is labelled Primary Control Module, and situated after
the rectifier and before a large transformer that appears to isolate the
following stages of the PSU. The aim is of course to use the schematic to
attempt to work out the cause of the failure and repair that too before it
blows up the replacement transistor or damages some other part(s).
The schematic is here: http://1drv.ms/1yBzYTN (png) or here:
http://1drv.ms/1xFXUnR (Eagle schematic). I may not have drawn it
logically, and may have some bits wrong, as it is quite difficult to
derive the schematic and it is easy to make mistakes. I don?t know how to
identify zener diodes, so all diodes are drawn as ordinary ones. I was also
unable to draw the transformers correctly as I don't know their spec and
pinout.
I have found some of the capacitors in the circuit to have a high-ish ESR.
C407 in particular has a high ESR, C404 has a high-ish ESR, and C303 needs
re-forming but I don?t yet have equipment that can produce a high enough DC
voltage (should be able to do this in a few days time). My plan is to
replace all three of these. Whether these would cause Q301 to pop I don?t
know, what do people think?
There are also some heat marks around D408 and possibly R415 (both seem to
test OK).
Are there any other bits of the circuit that I should check that might
cause Q301 to pop?
Any advice really appreciated!
Thanks
Rob
usually there are instructions in the footer of each msg. I *was* on
digest till the revamp and now I'm getting way more email than I want
and I don't know where the directions are to get back to digest mode. I
missed whatever email exchange this was.
On 11/4/2014 5:31 PM, Jim Carpenter wrote:
> On Tue, Nov 4, 2014 at 12:52 PM, Fred Cisin<cisin at xenosoft.com> wrote:
>
>>> SET DIGEST
>>>
>> Ah, back in the classic days of computers, people didn't understand
>> mailing lists, and sent their mailing list commands TO THE LIST.
>>
>> Are we going back to the way things used to be done?
>>
>>
> On nearly every mailing list I belong to the first SET DIGEST or
> UNSUBSCRIBE command that goes out on the list *always* sets off a
> storm of requests from other people. :(
>
> Jim
>
>
On 10/11/2014 04:06 PM, Brent Hilpert wrote:
> On 2014-Oct-11, at 1:57 AM, Rik Bos wrote:
>
>>>> Just noticed recently that the source from 1970 for the single-user HP BASIC
>>> has appeared on bitsavers (thanks Al), so working on getting that going now.
>>> Nice to have some period software for the machine.
Direct link?
>>> That was OCR'd from a listing that purchased from HP in 1971 so that I could
>>> hack on the BASIC interpreter that was running on the 2114 at my high school.
Same source? Got a link?
>> Probably Educational Basic HP24160A, there was a special configuration of
>> the HP 2114A/B combined with the HP 2748A paper tape reader and a HP 2760A
>> optical mark card reader and a HP 2752A Teleprinter delivered to schools and
>> Universities.
>> The whole combination without the Teleprinter was built in a 19"cabinet with
>> a small drawer at the top, it's purpose was to learn children and students
>> Basic.
>> The Educational basic differs from stand-alone HP 24000A Basic, it can read
>> a special kind of marked cards (HP 02760-9051) with basic commands on it.
>
> Haven't seen any mention or support for the card reader in either the interpreter or the PBS (Prepare Basic System) device configuration .. seems to be the standard version.
>
> I remember the special BASIC mark-sense cards from the 9830 + 9869A/7261A card reader at the high school I went to.
Penfield High, NY where I attended, had a 19" cabinet with an HP-2114B
(B?) and a ASR-33 console. There was also an HP-2761A Optical Mark
reader, and I'm not sure the printer.
At the time I used it, there were 4 "consoles" running and time slicing
was done on each line of basic. The card reader was one input, and the
printer was the output. The ASR-33 was the only interactive terminal the
previous year, but new this year were two crt serial terminals. They
were not the HP branded terminals.
There was a paper tape punch and a reader. The punch was disconnected
and sitting over on a shelf.
As I recall there was a dual 8" floppy drive inside the cabinet.
There was no login on the terminals. Files starting with an exclamation
point where invisible to directory listings.
I've not found a time-shared basic that matched this type of
configuration. Dick Stover (now deceased) was the systems operator for a
number of different schools in upstate New York that ran similar setups.
Is the HP24160A you mention a software system? or the bundling of
specific hardware? both? Is the BASIC multi-user?
There was a grading program in the system that, as I recall, was
triggered by a CALL -151 command in basic. Thus a teacher would include
the magic card that triggered the app, then include a card marked with
the correct answers, then as many cards to be graded as they liked. I
don't recall how this was ended. Might have been a special end card. The
printer would then print a grade report for each card. All other
processing on the other "consoles" would halt until the grading was
complete. Then the BASIC time slicing would resume where it left off.
I have some partial source listings from back then of the D&D program we
were working on. It used a number of "chained" programs to do: map
generation, map navigation, battle encounters, inventory management,
etc. We had functions to pack and unpack date into floats as I don't
recall the BASIC supporting direct integers.
I'd be very interested in any source that might be this version of
BASIC. I've looked at the Montana State University basic, but this does
not look like what I recall. Sources for some of this up on my site:
http://rikers.org/hp2100/
check out the "msu" directory.
I have:
HP-2116A (non-functional, yes, that's an A, not a B or a C)
HP-2100A (not powered up)
HP-2108A (functional)
HP-2112A (functional)
HP-7900 (broken chassis)
HP-7901 * 2 (never powered up)
HP-2748B Paper Tape reader
HP-2761A Optical Mark Reader
Geek porn:
http://rikers.org/gallery/hardware
I'd trade it all for a functional HP-2114B :) I loved the touch
sensitive switched on that model. I'm in SLC Utah if anyone wants to see
any of this.
There are two ways of managing your list subscriptions.
You can use the web interface at:
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or
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For those of you who wish to use email, send a message to
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Some email commands (put the command in the subject):
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Mailman:
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We'll sort out an updated FAQ real soon now.
--
Lawrence Wilkinson lawrence at ljw.me.uk
The IBM 360/30 page http://www.ljw.me.uk/ibm360
I was referred by Jon Johnston at http://www.hpmuseum.net/. he had mentioned this group would be able to assist in sourcing complete AS400 servers with CRTs to some collectors that maybe interested. I would like a museum to have them for their collection or a collector that would use them as functional servers. You can contact me via e-mail or cell 760-703-0986
Thanks for your time
Matt
Sent from my iPad
I'm working on a project relating to the IBM RT, where the original vendor distribution is not available (or hasn't been un-lost yet, and the "supported" release is X11R2 anyway). Do any of the much esteemed list members have in their posession a distribution of the X11R3 source? Preferrably one contemporary to the period when it would have actually been in use?
I have the source generously provided by X.org, but it seems a bit poorly curated and I'm not sure of its actual provenance. There are more than a few files which have much newer modification times than I would expect, and very few of the IBM-provided source patches for bug fixes (which I do have) will apply. In some cases the code is not even remotely similar. So... since I've run into trouble with the X server built from this source, I'm looking for a second opinion in the form of an X11R3 source distribution that has a known provenance.
Apparently there were also >700k of patches for X11R3 that MIT provided on the RT, which are mentioned in an IBM TSB. Of course now those published sources are no longer active, and I have no way of knowing whether they're already applied to the X11R3 source at X.org. From the IBM TSB:
--begin quote--
"Note that X11 release 3 distribution and the improvements made since
the release of X11r3 for the IBM RT are NOT AVAILABLE from either
the host ibmsupt, IBM's Advanced Workstations Division (Palo Alto),
or the ACSC. These are only availble directly from MIT, or other
locations on the Internet as described below.
The latest IBM/4.3 code (patches, etc.) is available via anonymous ftp
>from expo.lcs.mit.edu, the file name is:
contrib/ibm-rt.r3-fixes.tar.Z
The size of this file it is about 730k. The Scheifler et al announcement
follows.
--end quote--
If anybody knows of an archive where a copy of those patches might be found, that would be tremendous. So far I've come up empty-handed. Everything at MIT I've found is X11R4 or newer. Everybody seems to have been in a big rush to forget the older versions (possibly I could not blame them for that).
Anyone? X11R3 source and/or RT patches? Thanks!
ok
bear.
--
until further notice
