12 Aug
2006
12 Aug
'06
5 p.m.
I have an old (over 11yrs old) Hitachi 21"
CRT model CM2111MU (sub model 512), also known as a SuperScan Mc21HR RasterOps,
that seems to have a little overlap/failure to line-up on the colors (also
known as a convergence issue as I've been told). I can't seem to find anyone
in the area who still works on these damned things. Anyone have any pointers
to fixing convergence issues or know of anyone in the Hudson Valley area
(NY) that could fix this big bastard? Any assistance would be greatly
appeciated.
PS: I'm currently also working on acquiring a semi-working old MAC Classic
II (I believe), are there any resource sites that have technical sheets,
etc. to fixing it?
John Boffemmyer IV
12 Aug
12 Aug
5:49 p.m.
On Saturday 12 August 2006 08:00 pm, John Boffemmyer IV wrote:
I have an old (over 11yrs old) Hitachi 21"
CRT model CM2111MU (sub model 512), also known as a SuperScan Mc21HR
RasterOps, that seems to have a little overlap/failure to line-up on the
colors (also known as a convergence issue as I've been told). I can't seem
to find anyone in the area who still works on these damned things. Anyone
have any pointers to fixing convergence issues or know of anyone in the
Hudson Valley area (NY) that could fix this big bastard? Any assistance
would be greatly appeciated.
I've done that sort of thing, on TVs, and what you describe there ain't old.
TVs that were still using all vacuum tubes when I worked on them back in the
days I had my shop -- now they were OLD! Convergence used to be a real PITA,
because you had static convergence that was done by moving magnets on the
neck of the CRT (not to be confused with the purity magnets!) and then you
had dynamic convergence, which was typically 12-16 separate adjustments, all
of which interacted to some extent.
Stuff has come a long way since those days, and a lot of it is compensated
for by the factory attaching the deflection yoke and some very small (and
weak) magnets to the CRT and gluing everything down. The design of the face
of the tube has moved away from the old dot triad to triads of small stripes,
which gives you the advantage of the "Trinitron" design without the expense
of that tube.
If this came on all of a sudden rather than gradually, it's possible that the
glue or other goop holding one or more of those magnets in place has given
way and they've moved -- looking the thing over with a strong light and a
magnifying glass would perhaps reveal this and allow you to put stuff where
it belonged. If it did come on gradually then there's probably some circuit
component that's shifted over time and will need to be replaced.
I used to try and fix monitors. The last time I had one that I wanted working
I ended up tracking down some guy in the area who would work on them, taking
him 3 or 4 of the monitors that I had around, and telling him that he could
keep them if I got the one fixed that I wanted. As it turns out he didn't
fix it right, and I've not felt like being bothered to go back there and
hassle it since then. I did open that one up, but there was no way I was
going to attempt that repair. <shrug>
The other thing is, to do a proper convergence needs a signal that's going to
give you a stable pattern, although I suspect that's easier to do with a
computer driving it than not, I had to buy a little generator for TVs back
when, which I still have, but it's RF output only and limited in terms of
what frequencies it'll deal with. You'd need something that would deal with
the frequencies you're operating at. I know of one guy who actually went out
and spent the money on such a generator, and it's been several years since I
talked to him, I don't even know if he's still in business or not at this
point in time.
Monitors are apparently moving into the "not worth fixing" category any more.
And I just saw one offer of a couple of them on a local freecycle list. And
didn't go for them as I have pleny of them on hand now...
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
13 Aug
13 Aug
1:11 a.m.
Roy J. Tellason wrote:
The other thing is, to do a proper convergence needs
a signal that's going to
give you a stable pattern
I've seen at least one manufacturer built that functionality into their
displays, under control of a test switch inside the monitor. Nice idea, but I
suppose it's only relevant for screens that have their own microprocessor -
which probably also means that the convergence settings are stored in some
form of NV RAM and need a manufacturer's test program to change them :(
Monitors are apparently moving into the "not
worth fixing" category any more.
And I just saw one offer of a couple of them on a local freecycle list. And
didn't go for them as I have pleny of them on hand now...
Yep, I tend to see a handful of 17" and 19" displays offered on the local list
each week, usually from companies who have upgraded to LCDs and don't want the
hassle of disposing of their old CRTs responsibly. 21" screens being offered
free are still quite rare - or at least a modern-ish 21" screen; doubtless a
plea for some of the old 21" Hitachi/Sony goldfish bowl displays would turn up
quite a few...
3:05 p.m.
I've done that sort of thing, on TVs, and what
you describe there ain't old.
TVs that were still using all vacuum tubes when I worked on them back in the
days I had my shop -- now they were OLD! Convergence used to be a real PITA,
because you had static convergence that was done by moving magnets on the
neck of the CRT (not to be confused with the purity magnets!) and then you
had dynamic convergence, which was typically 12-16 separate adjustments, all
of which interacted to some extent.
Actually, having grown up with delta-gun CRTs, I find them much easier to
set up than the in-line type. Tweaking presets is a lot easier than
tilting the yoke and hoping....
[...]
I used to try and fix monitors. The last time I had
one that I wanted working
I ended up tracking down some guy in the area who would work on them, taking
him 3 or 4 of the monitors that I had around, and telling him that he could
keep them if I got the one fixed that I wanted. As it turns out he didn't
fix it right, and I've not felt like being bothered to go back there and
hassle it since then. I did open that one up, but there was no way I was
going to attempt that repair. <shrug>
Why not? Admittedly modern monitors are horrible to work on, with one PCB
that's totally inaccessible....
The other thing is, to do a proper convergence needs a signal that's going to
give you a stable pattern, although I suspect that's easier to do with a
computer driving it than not, I had to buy a little generator for TVs back
Indeed. With a computer, it's trivial to generate a cross-hatch pattern
(the main one needed for convergence).
For TVs, you either buy/build a cross-hatch generator (I remember
building one from a kit about 15 years ago, it was only a handful of ICs,
one of which was a TV sync generator chain). Or you use a home computer,
suitably programmed. There were programs for the BBC micro, C64, etc,
published in the magazines.
Monitors are apparently moving into the "not
worth fixing" category any more.
To be fair, very little of the stuff we talk about in this list is 'worth
fixing'. Why spend hours/weeks restoring a PDP11 when a PC has a lot more
CPU power? Well, we all know the answer to that...
I feel that the original monitor (and disk drives [1], keyboard, etc)
are as much a part of the machine, particularly (in the case of the
monitor) on a workstation, as the CPU. Therefore, I'd want to repair the
monitor if at all possible (even if, say, I have to re-wind a transformer
to do so,,)
Now no-name SVGA monitors are another matter. I do _NOT_ want any of
thsoe, I don't repair them, etc.
-tony
4:10 p.m.
On Sunday 13 August 2006 06:05 pm, Tony Duell wrote:
As in it's handled in software? I have not done any convergence adjustments
since those days, the stuff I'm dealing with any more hardly seems to need
it touched. Perhaps the only thing off in the original poster's monitor is
those static adjustments, if it suffered some kind of a physical shock,
which I would guess is at least worth looking at, seeing if something is
obviously out of place. I didn't see any response to my point about whether
this happened all of a sudden or gradually over time, though.
I always used to start with dots, myself, for the center convergence.
It depends on how much effort you want to put into something. With a pile of
monitors around here and no specific need for _that_ one, I didn't pursue
it. I did put it in storage, though, in a pile of monitors that's in
there...
I've done
that sort of thing, on TVs, and what you describe there ain't
old. TVs that were still using all vacuum tubes when I worked on them
back in the days I had my shop -- now they were OLD! Convergence used to
be a real PITA, because you had static convergence that was done by
moving magnets on the neck of the CRT (not to be confused with the purity
magnets!) and then you had dynamic convergence, which was typically
12-16 separate adjustments, all of which interacted to some extent.
Actually, having grown up with delta-gun CRTs, I find them much easier to
set up than the in-line type. Tweaking presets is a lot easier than
tilting the yoke and hoping.... [...]
This one in particular was a NEC Multisync um, 3a I think? After pulling the
back cover off you couldn't get at much of anything, except by taking it a
whole lot further apart, which involved undoing both side panels but to
swing them out meant that you had to disconnect a lot of stuff, so there was
no way obvious to me to get in there and do test points and such to find out
what was going on.
When I got it back from the guy I hooked it up to a dos-based machine and got
multiple images, as if the frequency it was trying to display wouldn't sync
properly or it couldn't hit the right frequency at all or something.
I remember looking at that time for what might be online for that monitor,
which turned out not to be all that much. Anybody know if this has changed?
I used to try and fix monitors. The last time I
had one that I wanted
working I ended up tracking down some guy in the area who would work on
them, taking him 3 or 4 of the monitors that I had around, and telling
him that he could keep them if I got the one fixed that I wanted. As it
turns out he didn't fix it right, and I've not felt like being bothered
to go back there and hassle it since then. I did open that one up, but
there was no way I was going to attempt that repair. <shrug>
Why not? Admittedly modern monitors are horrible to work on, with one PCB
that's totally inaccessible.... The other
thing is, to do a proper convergence needs a signal that's
going to give you a stable pattern, although I suspect that's easier to
do with a computer driving it than not, I had to buy a little generator
for TVs back
Indeed. With a computer, it's trivial to generate a cross-hatch pattern
(the main one needed for convergence). For TVs, you either buy/build a cross-hatch generator
(I remember
building one from a kit about 15 years ago, it was only a handful of ICs,
one of which was a TV sync generator chain). Or you use a home computer,
suitably programmed. There were programs for the BBC micro, C64, etc,
published in the magazines.
The one I bought back in 1974 (!) does include the dot, crosshatch, and color
bar patterns as well as a blank raster, for purity adjustments, but only
fixed sizes of them, not fewer or single ones, which I saw featured on some
instruments. It uses unijunction transistors as frequency dividers, and has
three trimpot adjustments on the back which needed to be tweaked often as it
wasn't terribly stable.
Monitors are
apparently moving into the "not worth fixing" category any
more.
To be fair, very little of the stuff we talk about in this list is 'worth
fixing'. Why spend hours/weeks restoring a PDP11 when a PC has a lot more
CPU power? Well, we all know the answer to that... I feel that the original monitor (and disk drives [1],
keyboard, etc)
are as much a part of the machine, particularly (in the case of the
monitor) on a workstation, as the CPU. Therefore, I'd want to repair the
monitor if at all possible (even if, say, I have to re-wind a transformer
to do so,,)
Some units are no doubt easier to work on than others.
Now no-name SVGA monitors are another matter. I do
_NOT_ want any of
thsoe, I don't repair them, etc.
The ones here all seem to have names on them, Packard Bell, Emachines,
Zenith Data Systems, MaxTech... :-)
--
Member of the toughest, meanest, deadliest, most unrelenting -- and
ablest -- form of life in this section of space, a critter that can
be killed but can't be tamed. --Robert A. Heinlein, "The Puppet Masters"
-
Information is more dangerous than cannon to a society ruled by lies. --James
M Dakin
14 Aug
14 Aug
2:35 p.m.
On Sunday 13 August 2006 06:05 pm, Tony Duell wrote:
As in it's handled in software? I have not done any convergence adjustments
No, not at all. AFAIK all monitors with microprocessor control use PIL
CRTs. I jsut find it easier to turn presets than to shift the yoke.
Now, as to what killed the delta-gun CRT... Well, Think of the effects of
external magnetic fields on the beams, and remember that the electron beam
moves perpendicular to the field. Resolve the earth's magnetic field into
vertical and horizontal components. The vertical component of said field
causes the beams to move horizontally, the horizontal component moves
them vertically.
BOTH components of the field cause convergence errors on a delta-gun CRT.
But on a PIL tube, the horizontal component of the earth's magnetic field
just shifts the picture vertically (slightly), and as the phospors are
put down in vertical strips, it doesn't cause a convergence error.
Now remember that the vertical component is essentially constant in a
given area, the effetive horizontal component changes if the CRT is
turned round, etc.
So a delta-gun tube has to be converged in the place it's going to be
used. A portable unit is almost impossible. A PIL tube has to be
converged at apporximately the right latitude, but apart from that, it
doesn't matter if you move the unit.
I've
done that sort of thing, on TVs, and what you describe there ain't
old. TVs that were still using all vacuum tubes when I worked on them
back in the days I had my shop -- now they were OLD! Convergence used to
be a real PITA, because you had static convergence that was done by
moving magnets on the neck of the CRT (not to be confused with the purity
magnets!) and then you had dynamic convergence, which was typically
12-16 separate adjustments, all of which interacted to some extent.
Actually, having grown up with delta-gun CRTs, I find them much easier to
set up than the in-line type. Tweaking presets is a lot easier than
tilting the yoke and hoping.... since those days, the stuff I'm dealing with any
more hardly seems to need
it touched. Perhaps the only thing off in the original poster's monitor is
You're lucky. I've never seen a modern-ish TV (that is, a TV recent
enough to be a PIL CRT, but not a plasma or LCD panel) that was
adequately converged.
those static adjustments, if it suffered some kind of
a physical shock,
which I would guess is at least worth looking at, seeing if something is
If it's suffered a shock, it's possible the 'aperture grille' (the
equivalent of the shadowmask) has come loose inside the CRT. This would
cause purity errors, and probably convergence errors too. In fact do we
know the OP's monitor has good purity (display a screen of each of the
primary colours -- red, green, blue -- does it look even, with no odd
coloured patches?)
obviously out of place. I didn't see any response
to my point about whether
this happened all of a sudden or gradually over time, though.
The other thing is, to do a proper convergence needs
a signal that's
going to give you a stable pattern, although I suspect that's easier to
do with a computer driving it than not, I had to buy a little generator
for TVs back
Indeed. With a computer, it's trivial to generate a cross-hatch pattern
(the main one needed for convergence). For TVs, you either buy/build a cross-hatch
generator (I remember
building one from a kit about 15 years ago, it was only a handful of ICs,
one of which was a TV sync generator chain). Or you use a home computer,
suitably programmed. There were programs for the BBC micro, C64, etc,
published in the magazines.
The one I bought back in 1974 (!) does include the dot, crosshatch, and color
bar patterns as well as a blank raster, for purity adjustments, but only
fixed sizes of them, not fewer or single ones, which I saw featured on some instruments. It uses unijunction transistors as
frequency dividers, and has
Mine at least uses ICs (mostly TTL from what I remember, along with a PAL
encoder chip and a sync generator).
monitor) on a
workstation, as the CPU. Therefore, I'd want to repair the
monitor if at all possible (even if, say, I have to re-wind a transformer
to do so,,)
Some units are no doubt easier to work on than others.
13 Aug
13 Aug
2:52 p.m.
I have an old (over 11yrs old) Hitachi 21"
CRT model CM2111MU (sub model 512), also known as a SuperScan Mc21HR RasterOps,
that seems to have a little overlap/failure to line-up on the colors (also
known as a convergence issue as I've been told). I can't seem to find anyone
in the area who still works on these damned things. Anyone have any pointers
to fixing convergence issues or know of anyone in the Hudson Valley area
(NY) that could fix this big bastard? Any assistance would be greatly
appeciated.
In gnneral there are 2 types of convergece adjustments : Static
convergence, which affects the whole screen (and which you tweak to get
the 3 colours lined up in the middle of the screen) and dynamic
convergence, which affects the edges and corners only.
IIRC, these terms come from the old delta-gun CRTs (the 3 electron guns
are at the corners of an equilateral triangle, like a capital delta). On
those tubes, static convergence was done with permanent magents (hence
steady, or staitc fields), while dynamic convergence was done by passing
carefully controlled currnts through coils around the CRT neck (hence
changing, or dynamic fields).
Your CRT is later than that, and has the 3 guns in a straight horizontal
line. With those, static convergernce is normally done by sets of ring
magnets on the back of the yoke, dynamic convergence by tilting the yoke
slightly (and wedging it with rubber blocks). On some high-end monitors
there are still dyanamic convergence circuits feeding assorted coils,
though.
Personally, I'd not want to try to do the convergence on a monitor
without the service manual. If you're mot that easily put off, try
displaying a cross-hatch pattern (a little matter of programming on a
computer moniotor), then mark the ring magnets on the back of the yoke so
you can get them back to the original position if you make things a lot
worse, then try fiddling with them. You will quickly get frustrated when
you find the beams do not go where you expect.
When you've got the centre correct, you can try tilting the yoke to sort
out the edges and corners.
The main problem is that you ahve to do this with the monitor on, and
there can be high-ish voltages (hundreds of volts) on the yoke windings
and connections. Take great care, have somebody nearby who knows how to
turn off the power, and so on.
-tony
14 Aug
14 Aug
2:07 p.m.
--- John Boffemmyer IV <newyork.techie at gmail.com>
wrote:
I have an old (over 11yrs old) Hitachi 21"
CRT model CM2111MU (sub model 512), also known as a
SuperScan Mc21HR RasterOps,
that seems to have a little overlap/failure to
line-up on the colors (also
known as a convergence issue as I've been told). I
can't seem to find anyone
in the area who still works on these damned things.
Anyone have any pointers
to fixing convergence issues or know of anyone in
the Hudson Valley area
(NY) that could fix this big bastard? Any assistance
would be greatly
appeciated.
Dude, as far as I know there are controls (trimpots?)
for making convergence adjustments inside the monitor.
IIRC some had them externally. I'm sure I've done it
in the past, but the method will be particular to
each monitor usually. A tech manual would prove to be
the most helpful. I'm sure there are forums specific
to monitor tweaking and repair also.
PS: I'm currently also working on acquiring a
semi-working old MAC Classic
II (I believe), are there any resource sites that
have technical sheets,
etc. to fixing it?
A good starting point is macmothership.com. Loads of
links and stuph.
John Boffemmyer IV
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