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Repair of old arcade monitor 1979

I've got a rare old vector arcade monitor from a "Warrior" arcade game
that came out in 1979. Everything works except that the picture is way
off center. To the point that about half of it is off-screen. I've
adjusted the horizontal and vertical controls as far as they go. So
I'm thinking I need to adjust the yoke. But I've never done that
before. I tried loosening the screw and I can rotate it which rotates
the picture. But I don't know how to move it to a different angle to
get the picture back in the middle. It's an old b&w monitor so I don't
have to worry about color convergience or anything like that. Can
someone give a novice a clue on how to go about this? Thanks!

John
 
T

Terry

Jan 1, 1970
0
I've got a rare old vector arcade monitor from a "Warrior" arcade game
that came out in 1979. Everything works except that the picture is way
off center. To the point that about half of it is off-screen. I've
adjusted the horizontal and vertical controls as far as they go. So
I'm thinking I need to adjust the yoke. But I've never done that
before. I tried loosening the screw and I can rotate it which rotates
the picture. But I don't know how to move it to a different angle to
get the picture back in the middle. It's an old b&w monitor so I don't
have to worry about color convergience or anything like that. Can
someone give a novice a clue on how to go about this? Thanks!

John
John: There may be, as with old B&W TV sets a couple of usually black
cardboard looking circular pieces with tabs often mounted on and comprising
part of the back of the yoke. Those could be rotated (gosh how rusty I am on
this!) to magnetically centre the whole raster (picture)? Try that? I guess
the 'black things' were somehow magnetic and steered the electron beam?
There used to also be an 'Ion trap' that had to also adjusted; if it was way
off the picture would show on the screen at all! IIRC the trap was to steer
the electron beam/s back towards the screen to avoid ion burn? because the
tube gun was manufactured not exactly pointing at the screen. The ion trap
looked like a springy open metal clip around the tube neck and contained a
small magnet about half the size of postage stamp. Maybe that's missing? If
so try a smallish magnet to see if affects the problem.
But stand to be corrected on any of this by those more knowledgeable. Terry
 
F

Farmer Giles

Jan 1, 1970
0
Terry said:
John: There may be, as with old B&W TV sets a couple of usually black
cardboard looking circular pieces with tabs often mounted on and comprising
part of the back of the yoke. Those could be rotated (gosh how rusty I am on
this!) to magnetically centre the whole raster (picture)? Try that? I guess
the 'black things' were somehow magnetic and steered the electron beam?
There used to also be an 'Ion trap' that had to also adjusted; if it was way
off the picture would show on the screen at all! IIRC the trap was to steer
the electron beam/s back towards the screen to avoid ion burn? because the
tube gun was manufactured not exactly pointing at the screen. The ion trap
looked like a springy open metal clip around the tube neck and contained a
small magnet about half the size of postage stamp. Maybe that's missing? If
so try a smallish magnet to see if affects the problem.
But stand to be corrected on any of this by those more knowledgeable. Terry

Ion traps were a good deal earlier than 1979. You are correct about the
tabs at the back of the yolk though - I think they were called 'shuffle
magnets' or something like that(but my memory might be no better than
yours here) - and they might well be the cause of the problem. Turning
them independently of each other should centralise the raster -
loosening and turning the yoke itself will only move the scan in the
horizontal plane (but make sure the yoke hasn't come loose and moved
away from the CRT).
All this assumes that it is a monochrome monitor.
 
F

Franc Zabkar

Jan 1, 1970
0
I've got a rare old vector arcade monitor from a "Warrior" arcade game
that came out in 1979. Everything works except that the picture is way
off center. To the point that about half of it is off-screen. I've
adjusted the horizontal and vertical controls as far as they go. So
I'm thinking I need to adjust the yoke. But I've never done that
before. I tried loosening the screw and I can rotate it which rotates
the picture. But I don't know how to move it to a different angle to
get the picture back in the middle. It's an old b&w monitor so I don't
have to worry about color convergience or anything like that. Can
someone give a novice a clue on how to go about this? Thanks!

John

Could it be a horizontal phase or horizontal delay issue somewhere in
the sync stripper circuit?

- Franc Zabkar
 
J

JANA

Jan 1, 1970
0
If the picture is off centre, there is obviously a component(s) that has
failed. It would be best to have the monitor properly serviced, rather than
try tweaking it to compensate for an error. I am sure that the monitor
originally did not have the fault you are describing. In a monitor that
old, it is more than likely that there are a number of high ESR capacitors,
and maybe even some resistor values that have drifted out with age, and
whatever use the monitor had.

--

JANA
_____


I've got a rare old vector arcade monitor from a "Warrior" arcade game
that came out in 1979. Everything works except that the picture is way
off center. To the point that about half of it is off-screen. I've
adjusted the horizontal and vertical controls as far as they go. So
I'm thinking I need to adjust the yoke. But I've never done that
before. I tried loosening the screw and I can rotate it which rotates
the picture. But I don't know how to move it to a different angle to
get the picture back in the middle. It's an old b&w monitor so I don't
have to worry about color convergience or anything like that. Can
someone give a novice a clue on how to go about this? Thanks!

John
 
K

Ken Layton

Jan 1, 1970
0
Suggest jumping to the forums at arcadecontrols.org

Depending on the make & model of the monitor there are prepacked
"capkits" made for certain monitors. Yours is certainly old enough to
have several failed electrolytic capacitors and a failed trimpot or
two.

Buy your capkits from Zanen Electronics at (806) 829-2780. Suggest also
checking out the Vector monitor FAQ & repair guide at ionpool.net
 
S

Sam Goldwasser

Jan 1, 1970
0
Farmer Giles said:
Ion traps were a good deal earlier than 1979. You are correct about
the tabs at the back of the yolk though - I think they were called
'shuffle magnets' or something like that(but my memory might be no
better than yours here) - and they might well be the cause of the
problem. Turning them independently of each other should centralise
the raster -
loosening and turning the yoke itself will only move the scan in the
horizontal plane (but make sure the yoke hasn't come loose and moved
away from the CRT).
All this assumes that it is a monochrome monitor.

Those never had enough range to cause what has been described, unless
perhaps deliberately totally messed up by someone before him.

--- sam | Sci.Electronics.Repair FAQ: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.
 
J

jhuie

Jan 1, 1970
0
Thank you all for your tips. It's good stuff. I was able to locate
the magnet adjustments but clearly there is something wrong with the
electronics. Zanen doesn't appear to offer a kit for this board. It's
an old Vectorbeam monitor from a "Warrior" game. And due to the rarity
and obscurity of this thing I think I'm going to defer to a
professional on this one after all. Thank you all for your help though!
 
J

James Sweet

Jan 1, 1970
0
JANA said:
If the picture is off centre, there is obviously a component(s) that has
failed. It would be best to have the monitor properly serviced, rather than
try tweaking it to compensate for an error. I am sure that the monitor
originally did not have the fault you are describing. In a monitor that
old, it is more than likely that there are a number of high ESR capacitors,
and maybe even some resistor values that have drifted out with age, and
whatever use the monitor had.


That's not always true, these things quite often got fiddled with, or
just mechanical vibration would muck up the adjustments, or the monitor
may have come from some other game and been swapped in without adjusting it.
 
J

James Sweet

Jan 1, 1970
0
Franc said:
Could it be a horizontal phase or horizontal delay issue somewhere in
the sync stripper circuit?

- Franc Zabkar


Not in a vector monitor, they're essentially audio amplifiers driving
the deflection yoke. These particular monitors have onboard DACs.
 
M

Michael Kennedy

Jan 1, 1970
0
Go check out rec.games.video.arcade.collecting
There are quiet a few knowledgeable people over there. You might even be
able to find someone to fix it for you there also..

- Mike
 
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