Getting my little monitor to work

  • Thread starter David Rutherford
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David Rutherford

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I purchased a little (oscilloscope?) monitor (5" screen) at a local
electronics supply store and am trying to get it to work. It came with a
mostly unreadable schematic that, according to a local TV repairman, is
not the correct one.

The manufacturer of the monitor is not printed anywhere on it, as far as
I can tell, so I can't contact them to get the correct schematic.
However, a schematic might not be necessary for what I need to do.

What I'm trying to do is get the electron gun to direct the electron
beam at the center of the screen. First, though, I need to find out how
to get it to operate. It's just a crt connected to a circuit board and
metal frame - no on/off switch. There's a 10-pin terminal on the circuit
board, but I don't know which pins are for what. There are also controls
for video center, v-hold, v-height, v-lin, and sub-bright.

Any help would be appreciated. Thanks.

Dave Rutherford
 
David Rutherford <drutherford@softcom.net> wrote in news:3F53F224.6B669169
@softcom.net:

I purchased a little (oscilloscope?) monitor (5" screen) at a local
electronics supply store and am trying to get it to work. It came with a
mostly unreadable schematic that, according to a local TV repairman, is
not the correct one.

The manufacturer of the monitor is not printed anywhere on it, as far as
I can tell, so I can't contact them to get the correct schematic.
However, a schematic might not be necessary for what I need to do.

What I'm trying to do is get the electron gun to direct the electron
beam at the center of the screen. First, though, I need to find out how
to get it to operate. It's just a crt connected to a circuit board and
metal frame - no on/off switch. There's a 10-pin terminal on the circuit
board, but I don't know which pins are for what. There are also controls
for video center, v-hold, v-height, v-lin, and sub-bright.

Any help would be appreciated. Thanks.

Dave Rutherford
Click to expand...
I am not sure what you inteded purpose is, but there is a fair amount of
information you are going to have to verify. I would start with a pinout
of the CRT, a verification of the existence of a power supply. and then
determine if the unit runs on 12 VDC, 120 VAC or some other voltage. This
can be a rather tedious chore. If it is as somple as you say it is, it
sounds like there is not power supply. If you don't have a power supply
for the beast, then it is only good for parts AFAIC.

r


--
"Any sufficiently advanced technology is indistinguishable from
magic."

Arthur C. Clarke (1917 - ), "Technology and the Future"
 
David Rutherford wrote:

I purchased a little (oscilloscope?) monitor (5" screen) at a local
electronics supply store and am trying to get it to work. It came with a
mostly unreadable schematic that, according to a local TV repairman, is
not the correct one.

The manufacturer of the monitor is not printed anywhere on it, as far as
I can tell, so I can't contact them to get the correct schematic.
However, a schematic might not be necessary for what I need to do.

What I'm trying to do is get the electron gun to direct the electron
beam at the center of the screen. First, though, I need to find out how
to get it to operate. It's just a crt connected to a circuit board and
metal frame - no on/off switch. There's a 10-pin terminal on the circuit
board, but I don't know which pins are for what. There are also controls
for video center, v-hold, v-height, v-lin, and sub-bright.

Any help would be appreciated. Thanks.

Dave Rutherford
Click to expand...
Betcha what you have there is a old Motorola style black and white 5 inch video
chassis. You need to feed it power, video and separate syncs. I think it needs
12VDC or some such. I even have one lying around, but I can't find it right now.
I had a schematic somewhere on how to hook it up... I'll try to find it.
 
Bill Janssen wrote:

David Rutherford wrote:

Rich Andrews wrote:

David Rutherford <drutherford@softcom.net> wrote in news:3F53F224.6B669169
@softcom.net:

I purchased a little (oscilloscope?) monitor (5" screen) at a local
electronics supply store and am trying to get it to work. It came with a
mostly unreadable schematic that, according to a local TV repairman, is
not the correct one.

The manufacturer of the monitor is not printed anywhere on it, as far as
I can tell, so I can't contact them to get the correct schematic.
However, a schematic might not be necessary for what I need to do.

What I'm trying to do is get the electron gun to direct the electron
beam at the center of the screen. First, though, I need to find out how
to get it to operate. It's just a crt connected to a circuit board and
metal frame - no on/off switch. There's a 10-pin terminal on the circuit
board, but I don't know which pins are for what. There are also controls
for video center, v-hold, v-height, v-lin, and sub-bright.

Any help would be appreciated. Thanks.

Dave Rutherford


I am not sure what you inteded purpose is, but there is a fair amount of
information you are going to have to verify. I would start with a pinout
of the CRT, a verification of the existence of a power supply. and then
determine if the unit runs on 12 VDC, 120 VAC or some other voltage. This
can be a rather tedious chore. If it is as somple as you say it is, it
sounds like there is not power supply. If you don't have a power supply
for the beast, then it is only good for parts AFAIC.

Thanks, Rich. I actually have two of them - each one with a CRT from a
different manufacturer. One CRT is made by Matsushita, the other is made
by Toshiba. There is no power supply with them - just the metal frame,
circuit board, and CRT.

The electronics store had a schematic and a monitor circuit card detail
laying with the monitors (these, apparently, weren't the right ones,
though, since the solder lines don't match). On the monitor circuit card
detail, however, a + 12V power source was called for. I'll try to draw
it here from what I can make out (it's a little blurred),

------ system gnd
------ }
------ } optional remote brightness control
------ }
------ special application
------ horiz. drive in
------ + 12V in
------ video in
------ vert. drive in

------ system gnd

Are these standard pin assignments or do they usually differ from unit
to unit? Also, what kind of 'video in', if any, would I need if I just
want to have a constant intensity electron beam always pointing at the
center of the screen (no modulation)?

I'm not very familiar with electronics, so I hope you won't mind if I
ask some basic questions. Can you point me to a website where I can
learn more about this kind of thing? Thanks.

Dave


r

--
"Any sufficiently advanced technology is indistinguishable from
magic."

Arthur C. Clarke (1917 - ), "Technology and the Future"

If you have an old XT computer, the cga connector will have the H drive, V drive

and at least one video connection. You may need a "pot" connected to the three
terminals for the "brightness" control. I would use about 100KOhm for the pot.

The schematic may not be for your unit but the design was pretty standard
so it won't be far off.

Bill K7NOM
Click to expand...
Oh yes another thing. I think you have to have the H drive to get the high voltage
for the CRT.

Bill K7NOM
 
Bill Janssen wrote:
If you have an old XT computer, the cga connector will have the H drive, V drive

and at least one video connection. You may need a "pot" connected to the three
terminals for the "brightness" control. I would use about 100KOhm for the pot.

The schematic may not be for your unit but the design was pretty standard
so it won't be far off.

Bill K7NOM
Click to expand...
Getting the monitor to work may be a little to much for me, due to my
lack of electronics knowledge. I'll give it a try until I reach the
point of diminishing returns (or diminishing patience). Thanks for all
the help, Bill.

Dave
 
David Rutherford (drutherford@softcom.net) writes:
Bill Janssen wrote:

If you have an old XT computer, the cga connector will have the H drive, V drive

and at least one video connection. You may need a "pot" connected to the three
terminals for the "brightness" control. I would use about 100KOhm for the pot.

The schematic may not be for your unit but the design was pretty standard
so it won't be far off.

Bill K7NOM

Getting the monitor to work may be a little to much for me, due to my
lack of electronics knowledge. I'll give it a try until I reach the
point of diminishing returns (or diminishing patience). Thanks for all
the help, Bill.

Dave
Click to expand...
Keep in mind that it's not going to do what you want. It's not an
oscilliscope, it's a video monitor. Only by adding external video
circuitry will you get your dot in the middle of the screen (and
since you didn't really say what you wanted the dot for, likely you'll
need more circuitry after that).

An oscilliscope is directly driven, so if you apply a signal to
the horizontal plates, the dot will move horizontally, the direction
defined by the polarity of the input signal. The same with the vertical
deflection.

With a monitor, that "dot" is constantly being deflected around
the screen, vertically, then down to the next line, and so forth.
The deflection is done with coils, and you won't get much if you
stop that scanning.

Michael
 
Keep in mind that it's not going to do what you want. It's not an
oscilliscope, it's a video monitor. Only by adding external video
circuitry will you get your dot in the middle of the screen (and
since you didn't really say what you wanted the dot for, likely you'll
need more circuitry after that).

An oscilliscope is directly driven, so if you apply a signal to
the horizontal plates, the dot will move horizontally, the direction
defined by the polarity of the input signal. The same with the vertical
deflection.

With a monitor, that "dot" is constantly being deflected around
the screen, vertically, then down to the next line, and so forth.
The deflection is done with coils, and you won't get much if you
stop that scanning.

Michael
Click to expand...
Well it's possible to wire a choke in place of the yoke on the chassis to
get the HV, then you can externally drive the deflection coils, but
oscilloscopes use electrostatic deflection, the electromagnetic deflection
on a normal CRT is very limited in bandwidth and not very linear. You can
get some interesting patterns but nothing that even comes close in
usefulness to the old Heathkit, Eico and similar low bandwidth oscilloscopes
that show up at fleamarkets and on ebay for $10 or so fairly often. Also if
the dot sits in the middle for even a fraction of a second at full
brightness it'll burn a hole in the phosphor.
 
David Rutherford <drutherford@softcom.net> wrote in news:3F54337B.9AFFAA78
@softcom.net:

A E wrote:

David Rutherford wrote:

I purchased a little (oscilloscope?) monitor (5" screen) at a local
electronics supply store and am trying to get it to work. It came
with a
mostly unreadable schematic that, according to a local TV repairman,
is
not the correct one.

The manufacturer of the monitor is not printed anywhere on it, as far
as
I can tell, so I can't contact them to get the correct schematic.
However, a schematic might not be necessary for what I need to do.

What I'm trying to do is get the electron gun to direct the electron
beam at the center of the screen. First, though, I need to find out
how
to get it to operate. It's just a crt connected to a circuit board
and
metal frame - no on/off switch. There's a 10-pin terminal on the
circuit
board, but I don't know which pins are for what. There are also
controls
for video center, v-hold, v-height, v-lin, and sub-bright.

Any help would be appreciated. Thanks.

Dave Rutherford

Betcha what you have there is a old Motorola style black and white 5
inch video
chassis. You need to feed it power, video and separate syncs. I think
it needs
12VDC or some such. I even have one lying around, but I can't find it
right now.
I had a schematic somewhere on how to hook it up... I'll try to find
it.

That would be great, thanks A E.

Dave
Click to expand...
I am not sure why you would want a single high intesity dot in the center
of the screen, but if you would take the yoke off the crt, that would stop
any sweep and you would have a single dot in the center.

r


--
"Any sufficiently advanced technology is indistinguishable from
magic."

Arthur C. Clarke (1917 - ), "Technology and the Future"
 
David Rutherford wrote:

A E wrote:

David Rutherford wrote:

I purchased a little (oscilloscope?) monitor (5" screen) at a local
electronics supply store and am trying to get it to work. It came with a
mostly unreadable schematic that, according to a local TV repairman, is
not the correct one.

The manufacturer of the monitor is not printed anywhere on it, as far as
I can tell, so I can't contact them to get the correct schematic.
However, a schematic might not be necessary for what I need to do.

What I'm trying to do is get the electron gun to direct the electron
beam at the center of the screen. First, though, I need to find out how
to get it to operate. It's just a crt connected to a circuit board and
metal frame - no on/off switch. There's a 10-pin terminal on the circuit
board, but I don't know which pins are for what. There are also controls
for video center, v-hold, v-height, v-lin, and sub-bright.

Any help would be appreciated. Thanks.

Dave Rutherford

Betcha what you have there is a old Motorola style black and white 5 inch video
chassis. You need to feed it power, video and separate syncs. I think it needs
12VDC or some such. I even have one lying around, but I can't find it right now.
I had a schematic somewhere on how to hook it up... I'll try to find it.

That would be great, thanks A E.

Dave
Click to expand...
http://www.dfpresource.org/monitor.png

Just be sure it's the same thing... According to my inventory the actual monitor is
buried two boxes deep...
As others have said, this is a video monitor.
 
Rich Andrews wrote:
I am not sure why you would want a single high intesity dot in the center
of the screen, but if you would take the yoke off the crt, that would stop
any sweep and you would have a single dot in the center.
Click to expand...
That sounds like it's probably the easiest way to concentrate the beam
at the center of the screen. I didn't want to bore anybody with the
details, that's why I didn't mention my reasons for wanting to center
the beam. I'm actually using it for a physics experiment.

Dave
 
A E wrote:
David Rutherford wrote:

A E wrote:

Betcha what you have there is a old Motorola style black and white 5 inch video
chassis. You need to feed it power, video and separate syncs. I think it needs
12VDC or some such. I even have one lying around, but I can't find it right now.
I had a schematic somewhere on how to hook it up... I'll try to find it.

That would be great, thanks A E.

Dave

http://www.dfpresource.org/monitor.png

Just be sure it's the same thing... According to my inventory the actual monitor is
buried two boxes deep...
As others have said, this is a video monitor.
Click to expand...
Thanks, A E. I'll check my monitor against your schematic.

Dave
 
David Rutherford <drutherford@softcom.net> writes:

Rich Andrews wrote:

I am not sure why you would want a single high intesity dot in the center
of the screen, but if you would take the yoke off the crt, that would stop
any sweep and you would have a single dot in the center.

That sounds like it's probably the easiest way to concentrate the beam
at the center of the screen. I didn't want to bore anybody with the
details, that's why I didn't mention my reasons for wanting to center
the beam. I'm actually using it for a physics experiment.
Click to expand...
Some people will pay a lot more attention to postings if they include the
reasons, not just the immediate needs.

--- sam | Sci.Electronics.Repair FAQ Home Page: http://www.repairfaq.org/
Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
+Lasers | Sam's Laser FAQ: http://www.repairfaq.org/sam/lasersam.htm
| Mirror Site Info: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: The email address in this message header may no longer work. To
contact me, please use the Feedback Form at repairfaq.org. Thanks.
 
Sam Goldwasser wrote:
David Rutherford <drutherford@softcom.net> writes:

Rich Andrews wrote:

I am not sure why you would want a single high intesity dot in the center
of the screen, but if you would take the yoke off the crt, that would stop
any sweep and you would have a single dot in the center.

That sounds like it's probably the easiest way to concentrate the beam
at the center of the screen. I didn't want to bore anybody with the
details, that's why I didn't mention my reasons for wanting to center
the beam. I'm actually using it for a physics experiment.

Some people will pay a lot more attention to postings if they include the
reasons, not just the immediate needs.
Click to expand...
And some people will pay a lot _less_ attention if they include the
reasons :^).

Dave
 
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