Hello Dave and Tom,
This is my first response to cctalk, so I don't know if it'll "take" or
not. Just a couple of comments: I've also got a CRT with crack outer glass.
I don't know what type of gel they used to bond the CRT to the outer
protective glass, but Tom's suggestion seem plausible--depends on whether
or not the "gel" is soluble by acetone and also whether or not the gel is
destroyed in the process. Even with optic cement, would it be able to fill
large voids left by dissolved gel? I don't have any idea--just asking. If
any void remains, it's going to appear as a large "bubble" in your viewing
area...
Also, I tend to think that gel and protective glass may only be for extra
protection. In the "old days" I used to see lots of CRT's that had no
protective glass bonded to the front. If you broke the front, you broke the
CRT itself. I seem to recall having broken a few of these things with
pellet guns when I was much younger and never getting the hoped-for
catastrophic implosion (my 6th grade science teacher warned us of when he
shot an old TV CRT with a .22 and created a massive and dangerous
implosion. Could it be that older and larger tubes were more dangerous for
some reason??). I don't know. Maybe the glass is thicker these days. I
still respect CRT's, not only for high voltage, but also for possible
imposion dangers.
Good luck on a solution.
Regards,
Robert Greenstreet
gstreet(a)indy.net
-----------------------------------------------------
Message: 20
Date: Mon, 15 Jul 2002 09:16:45 -0500
To: cctalk(a)classiccmp.org
From: Tom Uban <uban(a)ubanproductions.com>
Subject: Re: CRT problem
Reply-To: cctalk(a)classiccmp.org
Hi Dave,
I have a similar problem with a couple of CRTs from my Imlac graphics machine.
After doing some research, the I did locate a company which would rebuild the
CRT for something like $700, with no guarantee that they would not destroy the
tube. They also had expensive replacement tubes, which were not the correct
phosphor.
Another solution, which I haven't tried yet is to remove the CRT from it's
electronics
and soak the face in a bath of acetone for an extended period of time (or
until the
secondary lens is separated from the tube. Once separated, clean and reattach
using optic cement. This was suggested by a friend who repairs large antique
camera lenses. I'm not sure if acetone will dissolve the cement which holds
the
lens to the tube, so a pre-test may be a good idea.
Some people have indicated a fear of removing the lens from the tube face
thinking
that the tube may well implode without it. I do not think that will be the
case, but
I suppose that it is possible. I believe that the lens is simply added
protect from
day to day use for the face of the tube and is not inherently required to
maintain
the strength of the tube against the vacuum inside. In any case, as always,
great
care should be taken to protect you, your eyes, etc. when handling CRTs, as
they
do carry the risk of implosion.
--tom
At 10:18 PM 7/15/2002 +1200, you wrote:
>I have a 10 or12 inch green screen CRT off an HP 9845B I need to clean up. .
>It has been stored in a damp environment and the silicon rubber 'bonding'
>the protective glass screen to the front of the CRT proper has developed
>large mould spots in side itself for an inch or two around the outside edge
>of the screen. I guess I am looking for suggestions as to how to readily
>separate theses two glass items without scratching etc so I can clean and
>rebond them. I thought at first there was a cavity between the glass on the
>CRT face and the protective glass out front- just a seal of silicon rubber
>round the edge- but no such luck-- seems like the silicon rubber stuff
>covers the whole area of the tube face- so I need to chemically remove it or
>??
>Any ideas??
>
>The 9845B is running OK- getting a partial memory test failure at boot up
>but I don't expect that will be too hard to sort. Anyway-- that's next
>week's problem!
>
>Dave Brown
>Christchurch, NZ
OK, the continuing story goes on to its conclusion.
It looks I have been bit by the RX11 experiment.
Some evenings ago I swapped the RX11 for an RX211 card, but I did
not have the time to do some tests after the swap. Wish I did ...
But first some replies to suggestions made.
With the RX211 in slot 41, the DL11 in slot #40 and a M9302
+ I can access the diags at 765000 on the M9312 successful
+ I can access the PROM at 773000 on the M9312
+ access to CPU registers and MMR0-1-2 (777572 /4 /6) are all OK.
+ read/write the DL11 registers also OK!
??? I do not have a problem ???
Going back through my notes I see that the swap RX11 -> RX211
was the last action. So, back to the previous state: RX211 out,
RX11 in. Guess what. The hung condition is back.
The RX11 is a programmed I/O device. I knew that. But thanks
to Tony's e-mail that older cards *do not* wire CA1 to CB1 if
they do not use DMA, I checked the RX11. CA1 is not connected
to CB1. That explains the hung.
> It's OK to solder a wire (carefully) between the 'inside'
> end of these fingers to make a DL11 (or whatever) that will
> work in any slot. Some of my cards have been modified in
> this way by the previous owner. I don't do that -- I fit the
> wire-wrap jumper on the back of the backplane as DEC intended
Again, Tony has the same thoughts I had yesterday. I did consider
soldering a wire to the first 2 pins on the component side of the
RX11 card. I did not.
To make sure, I put the RX211 back in: all OK again.
I made a note that slot 41 has the NPR wire on the backplane cut
and that slot 40 has the NPR wired on the backplane.
By experiment I will check the NPR wire of the other UNIBUS slots.
You know why once you have seen the backplane of an 11/70.
However ... (I will check this again)
RX11 in slot 41 --> hung and we know why.
RX211 in slot 41 --> all OK and we know why.
G7273 double grant in slot 41 --> THE HUNG IS BACK! Huh??
Although the G7273 card puzzles me, I want to thank everybody for
their contribution to solve this problem. I learned a lot from it.
Also learned what that "SWR" column means in the M9312 manual.
I had it right under my nose Johnny! It is even on my website in the
tree "PDP-11/34A/CPU info/options/bootstrap". On that page all the
ROM tables are listed including links. http://home.hetnet.nl/~tshaj
kind regards,
- Henk.
I have a lexbook arlington 10, does anyone out their know where I can get a copy of the owners manual, factory software and especially any info on it's motherboard and manufacturer.
lexmark quit all support long ago.
note: I've expanded it to 16mb, 810mb hard drive, win 95b, it has 256 color 640x480 lcd.
it has a 50mhz 486 slc2 with 25mhz bus, floppy drive, com port and parallel port.
any info on the chip that goes in the blank spot for ethernet on board would be appreciated.
Hello Team
Excuse me, but the Christian Fandt e-mail address have not been available
could Somebody help me please????
Thank you very much for your attention.
Best Regards
Dario Rodriguez.
==================================================================================================
Hello Christian Fandt,
I hope you are ok..
My name is Dar?o Rodriguez and I work at Ericsson de Colombia Repair Center.I am in charge of equipment maintenance.
We have a equipment which is controlled by a Hewlett Packard calculator reference: HP 9825B that we looked at your web site http://www.classiccmp.org/mail-archive/classiccmp/2000-08/0176.html
We will really appreciate you help us to know if is still available to buy this unit, because our calculator is not working very well now, and one new could be better to us,or if it is not available, maybe, could you please help us to know if this calculator is replaced by other one?,
In the past we tried to replace this one by a Computer interface, but It have not been possible, do you know where do we find information about this process?,
Thank you very much for your attention,
We will expect your comments about this matter,
Best Regards
Dario Rodriguez.
Reading the replies, not from the screen, but printed, I notice
a comment from Tony. This could be important!
> Of course you might still have an open NPG jumper on the slot
> where the DL11-W is (this card does not short CA1 to CB1).
That's an eye-opener for me! I thought that the DL11 would
short CA1 to CB1. I guess that some cards that do not use DMA
(NPR) short these 2 pins and some *do not*.
Since the machine was originally with a remote console,
(hard lesson: DO take notes on any action you do to a PDP-11,
if you do: make better/more elaborate ones), I think that there
was no DL11 in it, but the Unibus serial remote console M8255
was in slot #40. I swapped the M8255 for an M7856.
Now, if the M8255 *does* bridge/use NPR ...
I will check this evening of course, no matter what pops up!
I will do the other tests anyway, and make notes! They will
be very useful for future reference.
Again, thanks all so far,
- Henk.
I've been working on trying to get a Sol Helios disk system up and running
so I can recover and archive a bunch of disk images. If I can't get it
working (I'd really like to get it running for its own sake), I'll get a
catweasel card, a conventional 8" disk, and attempt to write my own
bit-level decoding software to recover the disks.
Anyway, I found and fixed the first problem: one of the satellite circuit
boards on the persci had a tantalum cap that had a dead short, taking out
the whole +24V power supply (it used a 3-terminal rgulator that detected
the problem and cut off power, thus there was no pop nor any telltale burnt
traces or wires). I fixed that and things are working somewhat better, but
I still can't seek to any track except 0 (via the restore line).
After discovering that the schematics I have are for a somewhat different
revision of the logic board than I have (doh!), I tracked down the problem
to what appears to be a busted 74123 (not LS123, which is slightly
different logically). The positive trigger is always high, and the Q-bar
output is always low -- that is, the thing looks like it is always
triggered despite the fact that there is no edge on the trigger input.
I could remove the 74123, replace the resistor and cap and see if that
fixes it, but doing it would require a lot more disassembly than I'd like
to do without being confident that what I'm seeing really is a problem.
Here is where I need advice. I can't find my TTL databook, but it would
appear that the trigger inputs are edge triggered, not level triggered, right?
Secondly, I haven't done board-level design in more than 10 years, but from
what I recall, 99 times out of 100 when I thought I had tracked down a bug
to a back chip, it was something else (then again, that was during design,
not just working on ostensibly correctly designed boards). I have little
experience with the '123 since using one for any timing critical function
simply hasn't been kosher for the past 20 years at least. Does anybody
know in such a situation like this, is it more likely to be a bad cap or a
bad '123, or a short somewhere else on the trace? I can measure the
resistance of the R and it is in spec. I've buzzed the circuit to see that
the R and C are connected to the pins of the '123. Any other
suggestions? Oh, the C is a mylar (I think) with a 5% precision rating
stamped on it (100pf).
Thanks.
-----
Jim Battle == frustum(a)pacbell.net
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cctech(a)classiccmp.org
http://www.classiccmp.org/mailman/listinfo/cctech
I found a few interesting cards for the Apple ][ the other day.
On it are the markings "Computer Networking Specialists" with a copyright
of 1988. It has two whole chips: a 6116 and a PAL. The remaining
components are three caps, one which has blown. In fact, of all the cards
I found, they all have the same cap blown, in some cases completely
obliterated with only the two leads remaining with only a huge swath of
soot in the path of the explosion. The cap seems to filter the ground
line (it goes from what I believe is the GND pin on the ICs to the ground
plane on the card).
Each computer with the card had a cable with an RJ-45 connector on one end
and a four-pin flat connector on the other protuding from the case. I
found other computers without the card but with the cable. The inside end
of the cable (with the 4-pin connector) was loose. There is no mating
connector on the card for it either.
It seems to me that these computers were part of some network scheme, and
that these cards possibly held some networking firmware. How the cap blew
off the cards is a mystery. I could imagine a power spike coming down the
network cable and damaging the card, but like I said, the cable didn't
plug directly into the card, and I can't imagine the Apple ][ bus passing
along a power surge to the card from the cable. I didn't bother to check
any of the Apple's that I pulled the cards from to see if they were
working.
Anyway, anyone have any knowledge of these?
Sellam Ismail Vintage Computer Festival
------------------------------------------------------------------------------
International Man of Intrigue and Danger http://www.vintage.org
* Old computing resources for business and academia at www.VintageTech.com *
Thanks for the config switch info. The 9133H unit I picked up came with the
config switch in position 8 and I originally formatted it on the IPC with 8
volumes. Maybe there is a limit on how many volumes the IPC can mount at
the same time? Only the first 6 volumes appeared to be mounted
automatically. I change the config switch to position 2 and reformatted the
drive as 2 volumes and that seems like it might be a better choice.
What controls the 256/1024 byte sector size? Is that up to the OS format
routine? Is there a CS/80 or SS/80 spec available anywhere to find out more
about how these HPIB drives work?
Are there any other sources of software for the IPC besides Pete's IPC
website? http://www.coho.org/~pete/IPC/integral.html
Now that I have a hard drive I don't really have anything interesting to
load on it yet.
-Glen
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The 8291 is a GPIB Talker/Listener IC. It's in Volume II of the 1985 Intel Microsystem Components Handbook. I have Vol I but not Vol II so I can't give you any details about the part.
Joe
At 11:40 AM 7/12/02 -0500, you wrote:
>
>I've also removed an Intel P8291A, which has been just as hard to find
>information on, anything would be useful.
>
>Thanks!
>
>-- Pat
>
>
