Hi,
I have an old B&W "specialty" monitor which recently stopped working.
In the process of moving it around (to/from repair place) I noticed a
little black "tube magnet" dropping out when I took the cover off.
At the time I didn't think much of it (those in the know can chuckle now).
So, after a bout of replacing bad caps with no luck, I eventually broke
down and replaced the deflection board and the monitor sprang to life.
Much joy.
(note: "specialty" = designed for a specific computer with a special ECL
video connection and has no standard connector or interface. and no
schematics)
So, monitor is working. I proceed to adjust the H & V size, linearity, etc...
I notice that the bottom and sides will square up nicely but the top
edge has a large "dip" in the middle. No amount of trimmer fiddling will
fix this.
light goes off. "found" tube magnet is part of yoke assembly.
So, I notice where the missing magnet came from. Naturally it's on the
top side of the yoke assembly.
But - the "tube" has broken into 3 pieces (it was broke when I found it.
honest). I carefully glued it back together (no glue in the joints,
however) and replaced it. This helped a little but did not cure the
problem.
[note to reader: I never took that fields course. I know nothing of magnets.]
So,
- is a broken magnet pushed back together not as good as a whole magnet?
(strength wise)
- can I get a new magnet somewhere?
- is there anything special about these magnets?
- do normal monitor repair guys just have a box of these laying around?
- does this sort of thing happen all the time?
-brad
I was using boot rl0. That is what I get for doing things when I am
tired. I did not use PUTR to create the disk file just at. That is
likely the source of my problem. This should get me a ways down the
road.
Eric
I'm there, at the Marriott. Email me directly if you want to
get together for dinner or something. Also, any exhibitors know
what we're supposed to do tomorrow?
Bill S.
On Jul 15, 13:39, David Betz wrote:
>
> Thanks for your suggestions!
>
> On Jul 15, 2004, at 1:03 PM, Antonio Carlini wrote:
> > B/R5:10000000 DKA400:
> >
> > (that's 1 followed by 7 zeroes).
> >
>
> I tried this and ultimately got the same "DKA400: is offline"
message.
> I guess it doesn't like this CD-ROM drive either. This is the last
one
> I have to try. Maybe I can find someone with one at VCF East
tomorrow.
I've not tried to boot a VAXstation 4000 from CD-ROM, but I've had no
problem with lots of other classic machines using older Toshiba drives.
Almost all modern (newer than about mid-90s) drives understand the
SCSI command to set the blocksize to 512 bytes in software, but older
machines don't know to do that. I keep a couple of Toshibas just for
that reason; XM3201, XM3301 and XM3401 at least have a couple of pairs
of half-moon solder pads, near the SCSI connector, normally linked for
2048-byte blocks, but you can cut the tracks between one or both to set
512-byte blocks. The three different 512-byte settings are supposed to
be for Sun, SGI, and Intergraph, but I've never noticed much
difference. OTOH, I have a couple of Hitachis and an NEC which can be
set to 512-byte blocks, and they don't work too well (the Hitachis in
particular are very slow and generate lots of errors), so apparently
not all CD-ROM drives are created equal.
--
Pete Peter Turnbull
Network Manager
University of York
Hello,
I have wanted a PDP11 for years but currently do not have the space for
one so I have decided to do the next best thing use simh. I have
downloaded simh and the rt11 disk image but I am kind of stuck on where
to go. Does anyone know of any sites or documents available online that
cover configuration of simh and the installation and use of rt11. I
have done some messing around and have managed to boot the rt11 image by
using the commands
at rl0 rtv53_rl.dsk
at rl1 eric_pdp11_rt11.dsk <- This is a file that I intend to do my
install to. Is that wrong?
Boot rl1.
I choose the automatic option but then it wants me to mount a disk in
dl1 so that it can backup the media. I try to attach dl1 but I get an
error non existent device. If try to create the disk during the install
the install just errors out and dies.
Any help with this will be most appreciated.
Eric
Hi All,
Another great day at the auction. My $30 bought me:
5-Dec Alpha 4/233's
2-Dec MVII's all filled with qbus cards, no scsi (this time) but a almost
brand new RD54!! in one.
1 5' computer rack
and
a HP 9000/300 complete with:
-7959 S SCSI controller and disk
- 98730 S 32bit Davinci Graphics subsystem
-most of the cables, etc
The 9000 was given to me by a guy who won the lot it came in but only wanted
the peecee stuff.
If anybody wants to give it a good home it's yours for the taking; It's on a
rolling rack and is about the same size as the MVII's
Cheers
Tom
--
---
Please do not read this sig. If you have read this far, please unread back to
the beginning.
Hi
It should be noted that when broken, these cheap
magnets will lose some of their magnetism that can
not be recovered by simply gluing the piece together.
As was mentioned, finding others on scrap units is
the easiest. Positioning these is an art. They never
seem to do what one expects so take your time at
locating the best location and orientation. It most
likely will not be the same as it was originally.
Watch out for the anode lead and wear eye protection,
any time you are working on he monitor with the cover
off.
Dwight
>From: "John Lawson" <jpl15(a)panix.com>
>
>
> These are cylindrical, low-gauss ferrite magnets called 'trimming
>magnets' or 'pincushion magnets'. A lot of cheaper CRT devices use 'em to
>tweak the display. They're a pain in the butt, especially the ones near
>the front of the CRT that gradually get demagnetized with each power-on
>degauss cycle.
>
> They are sometimes available at larger 'real' hardware stores (in the
>US) like True Value, etc.
>
> Or, as was wisely suggested, cannibalize them from another junk tube.
>
>
> Chees
>
>
>John
>
>
>
>
these are indeed magnets and were usually the dirt cheap variety. They were set in place at the factory to "trim" the beam to overcome mechanical deviations in the gun and deflection assemblies internal to the crt. They were not all that powerful. The best source of replacement would be another old monitor that you can take the magnets out of.
best regards, Steve Thatcher
-----Original Message-----
From: Brad Parker <brad(a)heeltoe.com>
Sent: Jul 15, 2004 11:54 AM
To: "General Discussion: On-Topic and Off-Topic Posts" <cctalk(a)classiccmp.org>
Subject: Re: Monitor deflection magnets; what to do when one falls out & breaks?
Paul Koning wrote:
>
>It's probably not a magnet, but rather a ferrite core. You'd know the
>difference putting the pieces together -- if you feel no attraction or
>repulsion, it's not a permanent magnet.
Interesting. The pieces do attract.
Are ferrite cores magnetic?
(I would think a ferrite core would have wires wrapped around it)
These magnets are not connected to the wired internal yoke assembly -
they are glued to a "collar" which is close to the back of the tube.
The collar is round but the magnets are glued to make a square - I
assume this helps make the image square. (or not :-)
The magnets on the two sides are symmetric as are the top and bottom.
Both top and sides have two "tube magnets" but ared spaced slightly
differently. The sides have two magnets side by side with no gap.
The top and bottom have two magnets side by side with a a 1/4" gap.
I can see where the glue was holding the magnet. That's where I put it
back.
I assume the poles should be aligned, i.e. the poles of the two magnets should
be the same, producing a larger overall field (I presume)
>As for the problem, I wonder if the issue is that the core is in the
>wrong spot. It's part of the deflection magnetics assembly, and if
>it's misplaced then you'd certainly get problems like you describe.
>Take a look at the corresponding piece at the bottom of the yoke. I
>would expect things to be symmetric. The fact that the thing fell out
>suggests that it may have been out of position, and when you pushed it
>back in you may not have gotten it back where it actually belongs.
Well, it fell out onto the floor when I took the enclosure off :-)
-brad
I got this via email today:
---[ Snip ]---
For a magazine review of a file-viewing program, I?m trying to find data
files in a variety of old formats that would be used in testing. Would you
have any you could send or know someone who would have such files? I?m
interested in files from word processor, spreadsheet, database,
presentation, and graphics programs. The data files I?m looking for
include those from programs such as WordStar, DisplayWrite, Enable,
PFS:Write, MultiMate, dBase, FoxBase, Paradox, Lotus 1-2-3, Quattro Pro,
Freelance, Harvard Graphics, and the like. Thanks for your help.
Gary Berline
---[ Snip ]---
Please contact Gary directly at Gary_BerlineNOSPAM(a)NOSPAMziffdavis.com -
removing the obvious.
Erik Klein
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